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| UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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Where to buy Celotex/Kingspan/Alternative
Can anyone recommend a place to buy
Celotex or Kingspan at the best prices, or is there a cheaper solution that would do the job just as well? It's for my garden lodge... timber framed, sitting on brick built wall to about 500mm, all on a concrete, reinforced base and with tanking system to prevent any damp entering the sub-floor. Area is about 14m x 4.5m. The building is well away from the house (right at the bottom of the garden) and the space will be split into 2 areas... home/office with computers and creature comforts and the other area, a workshop. The roof is pitched with gable ends and covered with a good quality felt. The interior ceiling is vaulted with exposed beams, as I like the sense of space this gives. So, I'm looking to insulate the walls and roof elevations and could do with some advice on the best product or combination of products to use to get maximum performance, while remaining economically priced. I'd also be grateful for any adivce on heating solutions. Thanks for any info. dean. |
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Can anyone recommend a place to buy
Celotex or Kingspan at the best prices, http://www.secondsandco.co.uk Christian. |
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"Christian McArdle" wrote in message . net... Can anyone recommend a place to buy Celotex or Kingspan at the best prices, http://www.secondsandco.co.uk Christian. Seconded :-) My dad bought £1500 worth from them for a new build at a very significant discount. Jewsons who have been their main building materials supplier phoned up and told them because the boards were seconds the Building Controls officer would reject them as not up to standard. The BC officer apparently laughed at this :-) Sam |
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Christian McArdle wrote:
Can anyone recommend a place to buy Celotex or Kingspan at the best prices, http://www.secondsandco.co.uk Christian. Thanks Christian, I'll go take a look. I didn't fancy a day on the phone being asked what the last company quoted... not just yet! FWIW: Magnet are doing some great deals on sheet materials at the moment and they say they are doing it as a loss-leader, to get the punters in... now I have something to compare them with! cheers, d. |
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Andy Hall wrote:
I just posted some information on how I did all of this for somebody asking about heating for an outbuilding. Use Google Groups and search backa few days. Andy, I did read your thread and found it very interesting and informative. I only wish that my outbuilding was near enough to feed via a new circuit on the CH system... unfortunately, it's about 250ft away from the house! My lodge is made from 4x2" tannelised wood, and dressed with roofing underlay on the walls, with construction cladding over the top... the roof is WBP 18mm ply with torch-on felt on top of that... taking into consideration the ventilation gap behind the celotex, what thickness board could I go for and would I need to enlarge the cavity by deepening the joists and studs? Also, do you know of any online suppliers I can get a quote from? cheers deano. |
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On Mon, 25 Oct 2004 23:12:19 +0000 (UTC), DeanoH
wrote: Andy Hall wrote: I just posted some information on how I did all of this for somebody asking about heating for an outbuilding. Use Google Groups and search backa few days. Andy, I did read your thread and found it very interesting and informative. I only wish that my outbuilding was near enough to feed via a new circuit on the CH system... unfortunately, it's about 250ft away from the house! OK. In rough numbers, assuming you didn't insulate the floor, and your walls are about 2.5m high, if you use 50mm Celotex and divide equally, you're going to need about 4-5kW in the office bit and 3-4kW in the workshop bit if you are happy with 16-18 degrees in that part. These are round numbers based on my own calculations. It's easy enough to do the sums. Just look up the R value of the thickness of Celotex that you plan to use and calculate the U value from the reciprocal of it. Then measure the surfaces in square metres and multiply these by the U value and the temperature difference through the walls - usually -3 degrees is used for worst case outside. This will give you heatlosses in watts. For the floors you can get figures from radiator calculation programs on the web sites of Barlo or Myson radiators. In terms of the heating arrangement, you are presumably going to run electricity anyway, and with insulation, this is not getting too outrageous to heat with electricity. Alternatively, if you have mains gas you could run that and have a small boiler and radiators, or perhaps LPG into a small boiler. I wouldn't use portable LPG heaters though because of water vapour that will be produced. My lodge is made from 4x2" tannelised wood, and dressed with roofing underlay on the walls, with construction cladding over the top... the roof is WBP 18mm ply with torch-on felt on top of that... taking into consideration the ventilation gap behind the celotex, what thickness board could I go for and would I need to enlarge the cavity by deepening the joists and studs? If you look on the Celotex web site there are application notes which cover the options that you will need closely enough. I assume where you say 4x2, you mean that the 4" side is the total depth available? If so, you could perhaps go with 70mm Celotex and have a 20mm gap behind. You need to check actual measurements. If you want something fancier with exposed beams in the roof then you might have to go for something thinner for that - it really depends on whether you want to clad it. For my workshop I didn't bother because I actually fitted the Celotex over the rafters leaving the foil showing. The joists were boarded anyway and the area above is used for storage so I didn't care about the foil showing. For a cabin that I completed last year, I did care more about the appearance, so I put small wooden laths brad nailed to the rafters to make 20mm spacers, then fitted the Celotex against them. The ceiling was then clad over the top of the rafters, hiding them and the Celotex. Also, do you know of any online suppliers I can get a quote from? Well, there's the Seconds outfit that Christian mentioned. Have you bought all the other materials yet? I found that by hawking a complete project list around the merchants - I faxed each a shopping list and asked for a quote, it wasn't hard to get reasonable prices. I just picked the lowest overall quote but one. I didn't trust the cheapest not to cock up the delivery. ..andy To email, substitute .nospam with .gl |
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Andy Hall wrote:
OK. In rough numbers, assuming you didn't insulate the floor, and The floor consists of 12" concrete poured onto about 12" of crush (can you believe I had the concrete pumped through the house, the full 300ft to the end of the garden... that sure was an epic day). Once the low level wall was built, it and the floor was coated with liquid rubber, blinded with sand and then covered with polythene sheeting. 4" insulation boards were then laid to the whole area and the whole lot was screeded. The timber frame was then constructed inside the brick built wall, leaving a cavity which was breached and dressed with roofing fillets (arris rail) and lead flashing. your walls are about 2.5m high, if you use 50mm Celotex and divide equally, Sorry, you've lost me here... divide equally? you're going to need about 4-5kW in the office bit and 3-4kW in the workshop bit if you are happy with 16-18 degrees in that part. These are round numbers based on my own calculations. It's easy enough to do the sums. Just look up the R value of the thickness of Celotex that you plan to use and calculate the U value from the reciprocal of it. Then measure the surfaces in square metres and multiply these by the U value and the temperature difference through the walls - usually -3 degrees is used for worst case outside. This will give you heatlosses in watts. For the floors you can get figures from radiator calculation programs on the web sites of Barlo or Myson radiators. Maths was never my strong point! My walls are 8ft - height of a sheet of plasterboard - so near enough 2.5 metres. The two longest walls are 14 metres and the ends are 4 metres. The front wall has a standard single door and the back wall has french doors centred within it, opening onto a decked area. The two long walls have double-glazed casement windows with two openers to each window... the left wall has one 6'x 4' casement window, the right has 2! To calculate the area of the roof elevations, I need to recall my trigonometry from school... correct me if I get this wrong: Overall height of lodge = 4metres minus wall height of 2.4384m (8') = 1561.6m Therefore from end elevation of roof: Adjacent = 2000mm (half of overall width) Opposite = 1561.6mm (overall height minus wall height) Hypotenuse = 2537.44mm (I cheated this by using a scaled drawing in Adobe Illustrator as I had no angle values to hand apart from the 90°). Therefore total area = Long wall A = 14m x 2.4384m = 34.1376m - 1 window ((6')1.8288m x (4') 1.2192) = 2.718m = 31.4196m/sq plus Long wall B = 14m x 2.4384m = 34.1376m - 2 windows @ 5.436m = 28.7016m/sq plus End wall C = 4m x 2.4384m = 9.7536m - single door (2.032 x 0.813m) = 1.6520m = 8.1016m/sq plus End wall D = 4m x 2.4384m = 9.7536m - french doors @ 3.304m = 6.4496m/sq plus Gable end E = 1.5616m x 2m (opp x adj) = 3.1232m (calculated by rotating triangles to form a rectangle) plus Gable end F = 1.5616m x 2m (opp x adj) = 3.1232m/sq (calculated by rotating triangles to form a rectangle) plus Roof elevation (pitch) G = 14m x 2.53744m (hyp) = 35.5241m/sq plus Roof elevation (pitch) H = 14m x 2.53744m (hyp) = 35.5241m/sq Therefore total internal area of construction in square metres would be: 151.967m/sq Sorry to show all my workings out, but as I said I've never been confident with maths and could do with my results being confirmed! So, how do I now go about calculating the insulation and heating requirements using the result above? In terms of the heating arrangement, you are presumably going to run electricity anyway, and with insulation, this is not getting too outrageous to heat with electricity. Alternatively, if you have mains gas you could run that and have a small boiler and radiators, or perhaps LPG into a small boiler. I wouldn't use portable LPG heaters though because of water vapour that will be produced. I spoke to my local electrical retailer (high street not chain) and his opninion was that running gas (and water supply) underground and meeting all current regs, would be more expensive than employing a solution offered by one of the more modern electical heating products, currently on the market... I have the dimplex brochure to browse at my leisure! If you look on the Celotex web site there are application notes which cover the options that you will need closely enough. I assume where you say 4x2, you mean that the 4" side is the total depth available? If so, you could perhaps go with 70mm Celotex and have a 20mm gap behind. You need to check actual measurements. Understood... the minimum ventilation gap is what I was after... thanks. If you want something fancier with exposed beams in the roof then you might have to go for something thinner for that - it really depends on whether you want to clad it. For my workshop I didn't bother because I actually fitted the Celotex over the rafters leaving the foil showing. The joists were boarded anyway and the area above is used for storage so I didn't care about the foil showing. For a cabin that I completed last year, I did care more about the appearance, so I put small wooden laths brad nailed to the rafters to make 20mm spacers, then fitted the Celotex against them. The ceiling was then clad over the top of the rafters, hiding them and the Celotex. I think I understand the above! I want to leave a vaulted ceiling and plasterboard over the rafters (just like the walls) this would again give me my 4" of space behind the plasterboard to fit the celotex and leave a ventilation void... is this what you obtained by installing the laths? i.e. where did you put the laths - between the rafters or on their internal edge? As far as the interior design is concerned, I did consider the exposed beams route, but later rejected this as it would create a period look and my house is definately not, inside nor out, a period dwelling! As a graphic designer, anything I can do to make the space more minimalist and simply defined, the better! This is so my eye will not be distracted while working in the lodge... it's also the reason why many designers wear black! Have you bought all the other materials yet? I found that by hawking a complete project list around the merchants - I faxed each a shopping list and asked for a quote, it wasn't hard to get reasonable prices. I just picked the lowest overall quote but one. I didn't trust the cheapest not to cock up the delivery. Apart from the celotex and plasterboard, I can't see what other materials I would need (in bulk) that I could obtain from a single source! If you believe otherwise, please suggest! .andy Thanks very much for your time, advice and suggestions. deano. |
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On Tue, 26 Oct 2004 23:42:43 +0000 (UTC), DeanoH
wrote: Andy Hall wrote: OK. In rough numbers, assuming you didn't insulate the floor, and The floor consists of 12" concrete poured onto about 12" of crush (can you believe I had the concrete pumped through the house, the full 300ft to the end of the garden... that sure was an epic day). Once the low level wall was built, it and the floor was coated with liquid rubber, blinded with sand and then covered with polythene sheeting. 4" insulation boards were then laid to the whole area and the whole lot was screeded. The timber frame was then constructed inside the brick built wall, leaving a cavity which was breached and dressed with roofing fillets (arris rail) and lead flashing. OK, so you can pretty much use the U value of the insulating material on the floor for that surface. Heat loss is not going to worse than represented by that. Strictly, there is a formula taking into account the perimeter and area of the floor, but in this case it is not going to make a lot of difference as the floor loss will be small anyway. your walls are about 2.5m high, if you use 50mm Celotex and divide equally, Sorry, you've lost me here... divide equally? I meant if the building is divided equally in two - one half workshop other for office etc. and with different temperatures. Obviously if it is divided differently or temperatures are different you can do the sums accordingly. you're going to need about 4-5kW in the office bit and 3-4kW in the workshop bit if you are happy with 16-18 degrees in that part. These are round numbers based on my own calculations. It's easy enough to do the sums. Just look up the R value of the thickness of Celotex that you plan to use and calculate the U value from the reciprocal of it. Then measure the surfaces in square metres and multiply these by the U value and the temperature difference through the walls - usually -3 degrees is used for worst case outside. This will give you heatlosses in watts. For the floors you can get figures from radiator calculation programs on the web sites of Barlo or Myson radiators. Maths was never my strong point! My walls are 8ft - height of a sheet of plasterboard - so near enough 2.5 metres. The two longest walls are 14 metres and the ends are 4 metres. The front wall has a standard single door and the back wall has french doors centred within it, opening onto a decked area. The two long walls have double-glazed casement windows with two openers to each window... the left wall has one 6'x 4' casement window, the right has 2! To calculate the area of the roof elevations, I need to recall my trigonometry from school... correct me if I get this wrong: Overall height of lodge = 4metres minus wall height of 2.4384m (8') = 1561.6m Therefore from end elevation of roof: Adjacent = 2000mm (half of overall width) Opposite = 1561.6mm (overall height minus wall height) Hypotenuse = 2537.44mm (I cheated this by using a scaled drawing in Adobe Illustrator as I had no angle values to hand apart from the 90°). Therefore total area = Long wall A = 14m x 2.4384m = 34.1376m - 1 window ((6')1.8288m x (4') 1.2192) = 2.718m = 31.4196m/sq plus Long wall B = 14m x 2.4384m = 34.1376m - 2 windows @ 5.436m = 28.7016m/sq plus End wall C = 4m x 2.4384m = 9.7536m - single door (2.032 x 0.813m) = 1.6520m = 8.1016m/sq plus End wall D = 4m x 2.4384m = 9.7536m - french doors @ 3.304m = 6.4496m/sq plus Gable end E = 1.5616m x 2m (opp x adj) = 3.1232m (calculated by rotating triangles to form a rectangle) plus Gable end F = 1.5616m x 2m (opp x adj) = 3.1232m/sq (calculated by rotating triangles to form a rectangle) plus Roof elevation (pitch) G = 14m x 2.53744m (hyp) = 35.5241m/sq plus Roof elevation (pitch) H = 14m x 2.53744m (hyp) = 35.5241m/sq Therefore total internal area of construction in square metres would be: 151.967m/sq Sorry to show all my workings out, but as I said I've never been confident with maths and could do with my results being confirmed! So, how do I now go about calculating the insulation and heating requirements using the result above? OK, so you have to look at the heat loss through each element of each surface. In other words for each side wall, take the total area and subtract the window areas, for the end wall the doors and so on as you have done. Strictly speaking you should take into account all the components of the wall, e.g. the outer wood, the Celotex and the inner cladding, but you will find that the Celotex is the dominant one by far (as you would hope) so for this purpose you can just use that. 45mm Celotex has a U value of 0.5 W/m^2.K for 55mm it's 0.42 For other thicknesses you can use the table in http://www.celotex.co.uk/appl/PDF/SOL_PRS.pdf Just take the reciprocal of the R value. You can also combine if you want to use multiple thinner sheets. Add the R values and take the reciprocal of that. Heat loss for a surface is then given by Area in sq.m x U value x temperature difference. Usually you work with -3 degrees outside. So for an area of 5 sqm, 45mm Celotex and 21 degrees inside it becomes 5 x 0.5 x 18 = 45W. So for the Celotex covered areas just calculate each piece. Standard double glazing in wooden frames has a U value of 2.8 W/m^2.K, or 2.1 if it has low-emissivity glass. If the doors are substantially glass, then it;'s reasonable for this purpose to treat them as windows. So again take the areas and do the sums. If you were looking at what is necessary to do Building Regulations compliance, you ned to be more particular about the other components because they help a little towards insulation. Here it it doesn't matter because you are trying to get to a reasonable worst case for heating requirement. Obviously adjust the outside temperature used if you are in a colder or exposed position and want to oaccount for it. In terms of the heating arrangement, you are presumably going to run electricity anyway, and with insulation, this is not getting too outrageous to heat with electricity. Alternatively, if you have mains gas you could run that and have a small boiler and radiators, or perhaps LPG into a small boiler. I wouldn't use portable LPG heaters though because of water vapour that will be produced. I spoke to my local electrical retailer (high street not chain) and his opninion was that running gas (and water supply) underground and meeting all current regs, would be more expensive than employing a solution offered by one of the more modern electical heating products, currently on the market... I have the dimplex brochure to browse at my leisure! He's probably right. Obviously it would depend on your pattern of use, how long you want to take into account for the costs (i.e. how long will you live there) and to some extent taking a punt on energy costs. You have to run electricity anyway..... If you look on the Celotex web site there are application notes which cover the options that you will need closely enough. I assume where you say 4x2, you mean that the 4" side is the total depth available? If so, you could perhaps go with 70mm Celotex and have a 20mm gap behind. You need to check actual measurements. Understood... the minimum ventilation gap is what I was after... thanks. If you want something fancier with exposed beams in the roof then you might have to go for something thinner for that - it really depends on whether you want to clad it. For my workshop I didn't bother because I actually fitted the Celotex over the rafters leaving the foil showing. The joists were boarded anyway and the area above is used for storage so I didn't care about the foil showing. For a cabin that I completed last year, I did care more about the appearance, so I put small wooden laths brad nailed to the rafters to make 20mm spacers, then fitted the Celotex against them. The ceiling was then clad over the top of the rafters, hiding them and the Celotex. I think I understand the above! I want to leave a vaulted ceiling and plasterboard over the rafters (just like the walls) this would again give me my 4" of space behind the plasterboard to fit the celotex and leave a ventilation void... is this what you obtained by installing the laths? i.e. where did you put the laths - between the rafters or on their internal edge? OK. I was trying to understand whether you wanted to leave the rafters exposed. The laths were in behind purely to make sure that the Celotex was spaced away from the felt. If you cut the Celotex to be an interference fit between the rafters you don't really need them. Another technique is to put some between the rafters and some over the top. This reduces cold bridging - i.e. heat conducted through the rafters, but I am not sure that I would bother for this application. As far as the interior design is concerned, I did consider the exposed beams route, but later rejected this as it would create a period look and my house is definately not, inside nor out, a period dwelling! As a graphic designer, anything I can do to make the space more minimalist and simply defined, the better! This is so my eye will not be distracted while working in the lodge... it's also the reason why many designers wear black! Oh, I see. I thought that it was the "uniform". :-) Have you bought all the other materials yet? I found that by hawking a complete project list around the merchants - I faxed each a shopping list and asked for a quote, it wasn't hard to get reasonable prices. I just picked the lowest overall quote but one. I didn't trust the cheapest not to cock up the delivery. Apart from the celotex and plasterboard, I can't see what other materials I would need (in bulk) that I could obtain from a single source! If you believe otherwise, please suggest! Worth a try even with these, akthough you may still not reach the price point of Christian's Seconds outfit. .andy Thanks very much for your time, advice and suggestions. deano. ..andy To email, substitute .nospam with .gl |
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#11
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Andy Hall wrote:
OK, so you can pretty much use the U value of the insulating material on the floor for that surface. Heat loss is not going to worse than represented by that. Strictly, there is a formula taking into account the perimeter and area of the floor, but in this case it is not going to make a lot of difference as the floor loss will be small anyway. OK, I'll have to find that out, as I didn't buy or install that, but it shouldn't be too hard to get the U value. I meant if the building is divided equally in two - one half workshop other for office etc. and with different temperatures. Obviously if it is divided differently or temperatures are different you can do the sums accordingly. Ah! I see what you mean. Seeing as the two areas will have different use, it would be beneficial to calculate the insulation requirements of each? By the way, is the purpose of carrying out these calculations to establish the minimum thickness of Celotex required, in order that a standard level of insulation is achieved, or is it to obtain 'values' which would indicate which heating solution should be implemented? Sorry if I sound dumb, but this is all new to me and while I certainly appreciate that a bit of time spent now, calculating temperature parameters, could save me a lot of time and money, it's very involved compared to the opinions I have so far been offered by various friends and associates in the building industry! In summary, is the purpose of all this so that I can make an informed decision on purchasing the minimum of spec and amount of Celotex, while not setting myself up for huge bills resulting from having to overcompensate on a heating solution? OK, so you have to look at the heat loss through each element of each surface. In other words for each side wall, take the total area and subtract the window areas, for the end wall the doors and so on as you have done. Strictly speaking you should take into account all the components of the wall, e.g. the outer wood, the Celotex and the inner cladding, but you will find that the Celotex is the dominant one by far (as you would hope) so for this purpose you can just use that. 45mm Celotex has a U value of 0.5 W/m^2.K for 55mm it's 0.42 For other thicknesses you can use the table in http://www.celotex.co.uk/appl/PDF/SOL_PRS.pdf Just take the reciprocal of the R value. You can also combine if you want to use multiple thinner sheets. Add the R values and take the reciprocal of that. Heat loss for a surface is then given by Area in sq.m x U value x temperature difference. Usually you work with -3 degrees outside. So for an area of 5 sqm, 45mm Celotex and 21 degrees inside it becomes 5 x 0.5 x 18 = 45W. So for the Celotex covered areas just calculate each piece. Standard double glazing in wooden frames has a U value of 2.8 W/m^2.K, or 2.1 if it has low-emissivity glass. If the doors are substantially glass, then it;'s reasonable for this purpose to treat them as windows. So again take the areas and do the sums. OK, time for the maths bit again... to convert R to U... U=1/R So, for 55mm Celotex, R=2.35; U=0.42 Wall A (minus window) = 31.4196m/sq x 0.42 x 18 = 237.5W Wall B (minus windows) = 28.7016m/sq x 0.42 x 18 = 216.9W Wall C (minus door) = 8.1016m/sq x 0.42 x 18 = 61.2W Wall D (minus 2 doors) = 6.4496m/sq x 0.42 x 18 = 48.7W Gable end E and F = 6.2464m/sq x 0.42 x 18 = 47.2W Roof elevations G & H = 71.0482m/sq x 0.42 x 18 = 537.1W For windows and mainly glass doors, U=2.8 3 casement windows = 8.154m/sq x 2.80 x 18 = 410.9W 3 single doors = 4.956m/sq x 2.80 x 18 = 249.7W Total = 1809.2W Does this mean I need a heating solution that can produce 1.8kW of heat? Per hour? per day? etc etc! If you were looking at what is necessary to do Building Regulations compliance, you ned to be more particular about the other components because they help a little towards insulation. Here it it doesn't matter because you are trying to get to a reasonable worst case for heating requirement. Obviously adjust the outside temperature used if you are in a colder or exposed position and want to oaccount for it. Understood and agreed. He's probably right. Obviously it would depend on your pattern of use, how long you want to take into account for the costs (i.e. how long will you live there) and to some extent taking a punt on energy costs. You have to run electricity anyway..... Makes sense, and as I'm hoping to run a profitable business from the building (usage constraints aside), I would envision that this would become an overhead of the business and as such would be infinitesimal compared to accounting for rent (of which I'll have none) when calculating operating costs and charging such onto clients! OK. I was trying to understand whether you wanted to leave the rafters exposed. Sorry, should have made that clearer. The laths were in behind purely to make sure that the Celotex was spaced away from the felt. If you cut the Celotex to be an interference fit between the rafters you don't really need them. Interference fit? Held there by friction? Accurate cutting? Another technique is to put some between the rafters and some over the top. This reduces cold bridging - i.e. heat conducted through the rafters, but I am not sure that I would bother for this application. That would be guilding the lilly  Oh, I see. I thought that it was the "uniform". :-) It is I suppose... in an environment with lots of 'marketing types' who are constantly concerned about being 'en vogue', it's best not to waste valuable creative energy in the mornings by dressing to show individuality and personal taste! They would see this as a statement and would spend all day discussing your choice of attire for the day rather than focussing on making the 'big decision' about the concept(s) you've spent the last 3 months trying to get them to approve! It's complete irony that in order to achieve 'closure' (as the American's put it), creatives have to work with non-creatives! Worth a try even with these, akthough you may still not reach the price point of Christian's Seconds outfit. And would you consider this route? deano. |
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#12
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"DeanoH" wrote in message ... Andy Hall wrote: OK, so you can pretty much use the U value of the insulating material on the floor for that surface. Heat loss is not going to worse than represented by that. Strictly, there is a formula taking into account the perimeter and area of the floor, but in this case it is not going to make a lot of difference as the floor loss will be small anyway. OK, I'll have to find that out, as I didn't buy or install that, but it shouldn't be too hard to get the U value. I meant if the building is divided equally in two - one half workshop other for office etc. and with different temperatures. Obviously if it is divided differently or temperatures are different you can do the sums accordingly. Ah! I see what you mean. Seeing as the two areas will have different use, it would be beneficial to calculate the insulation requirements of each? By the way, is the purpose of carrying out these calculations to establish the minimum thickness of Celotex required, in order that a standard level of insulation is achieved, or is it to obtain 'values' which would indicate which heating solution should be implemented? Sorry if I sound dumb, but this is all new to me and while I certainly appreciate that a bit of time spent now, calculating temperature parameters, could save me a lot of time and money, it's very involved compared to the opinions I have so far been offered by various friends and associates in the building industry! In summary, is the purpose of all this so that I can make an informed decision on purchasing the minimum of spec and amount of Celotex, while not setting myself up for huge bills resulting from having to overcompensate on a heating solution? Don't armwave as you most likely will end up with the wrong solution. You will need to do some heat loss calcs. they are not difficult. The makers usually can help. The lower the U value the better the insulation value. The higher the R value the better. Finding the R value of the materials in a wall: brick, plasterboard, etc and the insulation, and then adding them gives the total R value. OK, so you have to look at the heat loss through each element of each surface. In other words for each side wall, take the total area and subtract the window areas, for the end wall the doors and so on as you have done. Strictly speaking you should take into account all the components of the wall, e.g. the outer wood, the Celotex and the inner cladding, but you will find that the Celotex is the dominant one by far (as you would hope) so for this purpose you can just use that. 45mm Celotex has a U value of 0.5 W/m^2.K for 55mm it's 0.42 For other thicknesses you can use the table in http://www.celotex.co.uk/appl/PDF/SOL_PRS.pdf Just take the reciprocal of the R value. You can also combine if you want to use multiple thinner sheets. Add the R values and take the reciprocal of that. Heat loss for a surface is then given by Area in sq.m x U value x temperature difference. Usually you work with -3 degrees outside. So for an area of 5 sqm, 45mm Celotex and 21 degrees inside it becomes 5 x 0.5 x 18 = 45W. So for the Celotex covered areas just calculate each piece. Standard double glazing in wooden frames has a U value of 2.8 W/m^2.K, or 2.1 if it has low-emissivity glass. If the doors are substantially glass, then it;'s reasonable for this purpose to treat them as windows. So again take the areas and do the sums. OK, time for the maths bit again... to convert R to U... U=1/R So, for 55mm Celotex, R=2.35; U=0.42 Wall A (minus window) = 31.4196m/sq x 0.42 x 18 = 237.5W Wall B (minus windows) = 28.7016m/sq x 0.42 x 18 = 216.9W Wall C (minus door) = 8.1016m/sq x 0.42 x 18 = 61.2W Wall D (minus 2 doors) = 6.4496m/sq x 0.42 x 18 = 48.7W Gable end E and F = 6.2464m/sq x 0.42 x 18 = 47.2W Roof elevations G & H = 71.0482m/sq x 0.42 x 18 = 537.1W For windows and mainly glass doors, U=2.8 3 casement windows = 8.154m/sq x 2.80 x 18 = 410.9W 3 single doors = 4.956m/sq x 2.80 x 18 = 249.7W Total = 1809.2W Does this mean I need a heating solution that can produce 1.8kW of heat? Per hour? per day? etc etc! If you were looking at what is necessary to do Building Regulations compliance, you ned to be more particular about the other components because they help a little towards insulation. Here it it doesn't matter because you are trying to get to a reasonable worst case for heating requirement. Obviously adjust the outside temperature used if you are in a colder or exposed position and want to oaccount for it. Understood and agreed. He's probably right. Obviously it would depend on your pattern of use, how long you want to take into account for the costs (i.e. how long will you live there) and to some extent taking a punt on energy costs. You have to run electricity anyway..... Makes sense, and as I'm hoping to run a profitable business from the building (usage constraints aside), I would envision that this would become an overhead of the business and as such would be infinitesimal compared to accounting for rent (of which I'll have none) when calculating operating costs and charging such onto clients! OK. I was trying to understand whether you wanted to leave the rafters exposed. Sorry, should have made that clearer. The laths were in behind purely to make sure that the Celotex was spaced away from the felt. If you cut the Celotex to be an interference fit between the rafters you don't really need them. Interference fit? Held there by friction? Accurate cutting? Another technique is to put some between the rafters and some over the top. This reduces cold bridging - i.e. heat conducted through the rafters, but I am not sure that I would bother for this application. That would be guilding the lilly Oh, I see. I thought that it was the "uniform". :-) It is I suppose... in an environment with lots of 'marketing types' who are constantly concerned about being 'en vogue', it's best not to waste valuable creative energy in the mornings by dressing to show individuality and personal taste! They would see this as a statement and would spend all day discussing your choice of attire for the day rather than focussing on making the 'big decision' about the concept(s) you've spent the last 3 months trying to get them to approve! It's complete irony that in order to achieve 'closure' (as the American's put it), creatives have to work with non-creatives! Worth a try even with these, akthough you may still not reach the price point of Christian's Seconds outfit. And would you consider this route? deano. |
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On Thu, 28 Oct 2004 23:24:03 +0000 (UTC), DeanoH
wrote: Andy Hall wrote: OK, so you can pretty much use the U value of the insulating material on the floor for that surface. Heat loss is not going to worse than represented by that. Strictly, there is a formula taking into account the perimeter and area of the floor, but in this case it is not going to make a lot of difference as the floor loss will be small anyway. OK, I'll have to find that out, as I didn't buy or install that, but it shouldn't be too hard to get the U value. If you were looking at Building Regulation compliance, it would be a different story, but for this it's good enough. I meant if the building is divided equally in two - one half workshop other for office etc. and with different temperatures. Obviously if it is divided differently or temperatures are different you can do the sums accordingly. Ah! I see what you mean. Seeing as the two areas will have different use, it would be beneficial to calculate the insulation requirements of each? By the way, is the purpose of carrying out these calculations to establish the minimum thickness of Celotex required, in order that a standard level of insulation is achieved, or is it to obtain 'values' which would indicate which heating solution should be implemented? You may want to think about what temperatures and patterns of use as well. If you were constructing the building to meet Building Regulations, there are guidelines for each element and the approach is called the elemental method. You can read more about it in the Approved Document to Part L1 on www.odpm.gov.uk Basically there are maxima for each component that are allowed if you are in a situation where the building, by size, location, use etc. is controlled by the Building Regulations. In that case you would have had to make an application to the local authority and they would inspect your work. If you are not required to work to Building Regulations because the building is exempt, (you can look on any local authority web site for information on this or again on the ODPM site), then insulation is up to you. Since you are paying, then you have to do the trade off between insulation capital cost and the cost of running the heating. If you are using a more expensive fuel like electricity, then you will probably want to spend more on insulation. I would sit down and think about expected use patterns the year round - for example will you want to trudge down there when it is ****ing with rain horizontally? The go from there. If in doubr, it probably pays to err towards more insulation now, because it will be a pain to add later. Sorry if I sound dumb, but this is all new to me and while I certainly appreciate that a bit of time spent now, calculating temperature parameters, could save me a lot of time and money, it's very involved compared to the opinions I have so far been offered by various friends and associates in the building industry! In summary, is the purpose of all this so that I can make an informed decision on purchasing the minimum of spec and amount of Celotex, while not setting myself up for huge bills resulting from having to overcompensate on a heating solution? Exactly. You can pick a given size of Celotex and work out the heat loss for the building at given temperatures. One part of the exercise is to ensure that you put in enough heating to reach the temperatures you want inside for the coldest outside. The other is to do the cost trade off. To do that one, you can look at average monthly temperatures, take the predicted use pattern for that month and hence the energy use and cost based on that outside temperature. You have to decide on what the pattern of use is, though. OK, so you have to look at the heat loss through each element of each surface. In other words for each side wall, take the total area and subtract the window areas, for the end wall the doors and so on as you have done. Strictly speaking you should take into account all the components of the wall, e.g. the outer wood, the Celotex and the inner cladding, but you will find that the Celotex is the dominant one by far (as you would hope) so for this purpose you can just use that. 45mm Celotex has a U value of 0.5 W/m^2.K for 55mm it's 0.42 For other thicknesses you can use the table in http://www.celotex.co.uk/appl/PDF/SOL_PRS.pdf Just take the reciprocal of the R value. You can also combine if you want to use multiple thinner sheets. Add the R values and take the reciprocal of that. Heat loss for a surface is then given by Area in sq.m x U value x temperature difference. Usually you work with -3 degrees outside. So for an area of 5 sqm, 45mm Celotex and 21 degrees inside it becomes 5 x 0.5 x 18 = 45W. So for the Celotex covered areas just calculate each piece. Standard double glazing in wooden frames has a U value of 2.8 W/m^2.K, or 2.1 if it has low-emissivity glass. If the doors are substantially glass, then it;'s reasonable for this purpose to treat them as windows. So again take the areas and do the sums. OK, time for the maths bit again... to convert R to U... U=1/R So, for 55mm Celotex, R=2.35; U=0.42 Wall A (minus window) = 31.4196m/sq x 0.42 x 18 = 237.5W Wall B (minus windows) = 28.7016m/sq x 0.42 x 18 = 216.9W Wall C (minus door) = 8.1016m/sq x 0.42 x 18 = 61.2W Wall D (minus 2 doors) = 6.4496m/sq x 0.42 x 18 = 48.7W Gable end E and F = 6.2464m/sq x 0.42 x 18 = 47.2W Roof elevations G & H = 71.0482m/sq x 0.42 x 18 = 537.1W For windows and mainly glass doors, U=2.8 3 casement windows = 8.154m/sq x 2.80 x 18 = 410.9W 3 single doors = 4.956m/sq x 2.80 x 18 = 249.7W Total = 1809.2W Does this mean I need a heating solution that can produce 1.8kW of heat? Per hour? per day? etc etc! OK, so you've used 18 degrees as the temperature difference from inside to outside. That would mean that if it drops to -3 outside, you would have +15 inside which might be OK for a workshop but a bit chilly for sitting around. The typical inside (lounge) temperature used for design purposes is +21 degrees, so the temperature difference is then 24 degrees. If you wanted to achieve that, then you would need to multiply your figure by 24/18 which is approximately 2.4kW In other words, when it's -3 outside, a 2.4kW heater would maintain 21 degrees inside. There is also one more component that should be taken into account. You won't want to have a hermetically sealed box, so some air change needs to be included. To calculate this, you need to take the volume in cubic metres and multiply by 0.33 and the temperature difference again. This would give you the heat requirement to cover one air change per hour. However, the normal design criterion for a living room, games room etc. is 1.5 air changes per hour, so to do the whole lot it would be Volume x 0.33 x 1.5 x temperature_difference. Answer again is in Watts and you add that in. It could be as much heat as for the loss through the walls or even more. If you were looking at what is necessary to do Building Regulations compliance, you ned to be more particular about the other components because they help a little towards insulation. Here it it doesn't matter because you are trying to get to a reasonable worst case for heating requirement. Obviously adjust the outside temperature used if you are in a colder or exposed position and want to oaccount for it. Understood and agreed. He's probably right. Obviously it would depend on your pattern of use, how long you want to take into account for the costs (i.e. how long will you live there) and to some extent taking a punt on energy costs. You have to run electricity anyway..... Makes sense, and as I'm hoping to run a profitable business from the building (usage constraints aside), I would envision that this would become an overhead of the business and as such would be infinitesimal compared to accounting for rent (of which I'll have none) when calculating operating costs and charging such onto clients! OK. I was trying to understand whether you wanted to leave the rafters exposed. Sorry, should have made that clearer. The laths were in behind purely to make sure that the Celotex was spaced away from the felt. If you cut the Celotex to be an interference fit between the rafters you don't really need them. Interference fit? Held there by friction? Accurate cutting? Let's say your rafters are 500-600mm apart. You could cut the Celotex about 3-5mm oversize and it will squash in with a friction fit. If it's at size or slightly less, you tape them to the rafters with foil tape. One other thing is to not to forget to put some vents to the outside from behind the Celotex. When I did my workshop project, I used soffit vents (round plastic vents with a grille to keep out insects) that fitted into holes drilled under the eaves, one between every pair of rafters each side. You can put them in a different position, but ventilation is important. Another thing that I did was to coat the inside wood surfaces with clear Cuprinol solvent based wood preservative before putting in the Celotex and covering over. Also, at this stage, have a think about the electrics. If you want to hide them and use flush mount fittings, then a good way is to put in conduits and outlet back boxes and to then run PVC singles wiring to connect them together. I went for function over form and used three compartment trunking everywhere, surface mounted. This allows me to add things as I go or if necessary move them without disrupting the walls. Another technique is to put some between the rafters and some over the top. This reduces cold bridging - i.e. heat conducted through the rafters, but I am not sure that I would bother for this application. That would be guilding the lilly Oh, I see. I thought that it was the "uniform". :-) It is I suppose... in an environment with lots of 'marketing types' who are constantly concerned about being 'en vogue', it's best not to waste valuable creative energy in the mornings by dressing to show individuality and personal taste! They would see this as a statement and would spend all day discussing your choice of attire for the day rather than focussing on making the 'big decision' about the concept(s) you've spent the last 3 months trying to get them to approve! It's complete irony that in order to achieve 'closure' (as the American's put it), creatives have to work with non-creatives! Hmm. I think I'd lose patience with that, but I can certainly relate to keeping customers focussed on the subject in hand. Personally speaking, I am quite left-brained with the exception of music. Visually, I know what I like and what I don't, and would far rather see a limited set of choices and work from those than be bombarded with 20 choices. Worth a try even with these, akthough you may still not reach the price point of Christian's Seconds outfit. And would you consider this route? Definitely. It doesn't mattter if the odd sheet is slightly dinged, even. You can cut that out. I didn't bother because I was able to get a reasonable price for all the project materials from Jewsons. deano. ..andy To email, substitute .nospam with .gl |
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On Fri, 29 Oct 2004 00:43:33 +0100, "IMM" wrote:
"DeanoH" wrote in message The lower the U value the better the insulation value. The higher the R value the better. Finding the R value of the materials in a wall: brick, plasterboard, etc and the insulation, and then adding them gives the total R value. While this is true, for this exercise, the resultant R value (and U value) are going to be so dominated by the Celotex rather than the wood and plasterboard that they are not worth bothering with.. ..andy To email, substitute .nospam with .gl |
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Andy Hall wrote:
If you were looking at Building Regulation compliance, it would be a different story, but for this it's good enough. Yep. You may want to think about what temperatures and patterns of use as well. If you were constructing the building to meet Building Regulations, there are guidelines for each element and the approach is called the elemental method. You can read more about it in the Approved Document to Part L1 on www.odpm.gov.uk Basically there are maxima for each component that are allowed if you are in a situation where the building, by size, location, use etc. is controlled by the Building Regulations. In that case you would have had to make an application to the local authority and they would inspect your work. If you are not required to work to Building Regulations because the building is exempt, (you can look on any local authority web site for information on this or again on the ODPM site), then insulation is up to you. Since you are paying, then you have to do the trade off between insulation capital cost and the cost of running the heating. If you are using a more expensive fuel like electricity, then you will probably want to spend more on insulation. I would sit down and think about expected use patterns the year round - for example will you want to trudge down there when it is ****ing with rain horizontally? The go from there. If in doubr, it probably pays to err towards more insulation now, because it will be a pain to add later. The office part of the building will probably be used constantly, come rain or shine (or snow!), and I can also see me being in there until late at night on some occassions, such is the nature of the design business. The workshop part probably won't be used as much... maybe once or twice a week. Exactly. You can pick a given size of Celotex and work out the heat loss for the building at given temperatures. How does the result of the equation I worked out in my previous post (1809.2W) indicate which heating solution and output rating I would need, to maintain the target temperature inside the lodge? I know I might be jumping the gun a bit here as I have yet to allow for air- change, but I was just wondering! One part of the exercise is to ensure that you put in enough heating to reach the temperatures you want inside for the coldest outside. The other is to do the cost trade off. To do that one, you can look at average monthly temperatures, take the predicted use pattern for that month and hence the energy use and cost based on that outside temperature. You have to decide on what the pattern of use is, though. As above, constant use for the office but not for the workshop. OK, so you've used 18 degrees as the temperature difference from inside to outside. That would mean that if it drops to -3 outside, you would have +15 inside which might be OK for a workshop but a bit chilly for sitting around. The typical inside (lounge) temperature used for design purposes is +21 degrees, so the temperature difference is then 24 degrees. If you wanted to achieve that, then you would need to multiply your figure by 24/18 which is approximately 2.4kW That's where my maths lets me down! I would have recalculated the whole thing again using the new value of 24°! I assume that multiplying my result of 1,809.2W by 24/18 saves me doing that and gives me the same result? (Rhetorical question, as I'll try this offline!). In other words, when it's -3 outside, a 2.4kW heater would maintain 21 degrees inside. Ah! So this answers my question above about the relationship between the result of the calculations and the heating output required? Apart from factoring in the air-change, of course! There is also one more component that should be taken into account. You won't want to have a hermetically sealed box, so some air change needs to be included. To calculate this, you need to take the volume in cubic metres and multiply by 0.33 and the temperature difference again. This would give you the heat requirement to cover one air change per hour. However, the normal design criterion for a living room, games room etc. is 1.5 air changes per hour, so to do the whole lot it would be Volume x 0.33 x 1.5 x temperature_difference. Answer again is in Watts and you add that in. It could be as much heat as for the loss through the walls or even more. Undertood! I'm not quite sure how to calculate the volume in the roof space... if the pitch of the roof was 45°, I could just flip one side through 180° at the apex and treat it as a rectoid (???), but it's not 45°... I'll have to google this one! Let's say your rafters are 500-600mm apart. You could cut the Celotex about 3-5mm oversize and it will squash in with a friction fit. If it's at size or slightly less, you tape them to the rafters with foil tape. Yep, a good friend of mine suggested using the tape, even if the interference fit is right... he said it helps when tacking the walls. One other thing is to not to forget to put some vents to the outside from behind the Celotex. When I did my workshop project, I used soffit vents (round plastic vents with a grille to keep out insects) that fitted into holes drilled under the eaves, one between every pair of rafters each side. You can put them in a different position, but ventilation is important. I was wondering what to do about this, there are currently no soffits in place and the space between the rafters is just open! I was thinking about sourcing some kind of mesh material that would allow the through- flow of air, but not insects! Is there a product that you can think of that would be suitable for this or is the only realistic option to fit wooden soffits and then cut holes between each rafter and fit soffit vents? If there was something that I could employ which was already perforated, then this would save time and a little money! Something like pegboard, but with smaller holes! Any ideas? Another thing that I did was to coat the inside wood surfaces with clear Cuprinol solvent based wood preservative before putting in the Celotex and covering over. Were your timbers tannelised? Would you recommend this even if they are? Also, at this stage, have a think about the electrics. If you want to hide them and use flush mount fittings, then a good way is to put in conduits and outlet back boxes and to then run PVC singles wiring to connect them together. I went for function over form and used three compartment trunking everywhere, surface mounted. This allows me to add things as I go or if necessary move them without disrupting the walls. That's really the stage I'm at now! I have the cable and the pattress boxes and I came to an abrupt hault because I obviously need to run a separate ring main for the electrical heating if that was what I going to go for! This got me thinking about the heating, and then the insulation and then hence the start of this thread! I have recently completed some fairly major renovations to the house, in that we had the rear left corner of the house removed downstairs, so that we could extend our tiny kitchen to take up some of the space at the back of my garage (what a difference it has made, but that's another story!). One of the things I learnt during this, as I was pretty hands on with the project, was to set noggins between the studs at a height which matched the desired position of the wall sockets. The noggins were set back at such a distance from the front of the studs, so that when the pattress boxes were attached to the noggins, they would protrude slightly proud of the innermost face of the studs. This meant that when the plasterboards were offered up, a swift bash of the boards, around the area of the pattresses, would result in an impression of the corners of the wall boxes being left in the back of the plasterboard... the perfect template! Although you probably know that little trick already! Anyway, this is what I intend to do in the lodge. I'm just not yet sure whether to position the mains ring at skirting board height (or just above) or to run it round at desk height! What did you do? What pros and cons did you consider? I'm thinking desk height would keep the ring above any potential dampness and would permit easier access via a cable tray at the back of the desks or some such device. I did consider the conduit route, but that proved fairly expensive when I used it at a previous office premises! Do you think the trunking within the walls would really be necessary? I know it is probably part of the "perfect build" which your project sounds like it definitely was, but, while not wanting to cut too many corners (where it matters), cost is a major issue for me and I need to save where I can! On the subject of electrics, I'm still quite unsure of what lighting fixtures to install in the building. Lighting is, and always has been, a major issue for me. I have always hated dingy rooms! And I don't want to end up with a harshly lit space! I want to create some mood lighting (for the creative looke/feel) and some task lighting for when working on the computers while referencing paperwork on the desktop. I obviously want to avoid screen glare and above all, not end up spending an absolute fortune on the installation, which I am apt to do when it comes to lighting... it's one of my weaknesses Have you any experience on this subject? Do you know of any products on the market that provide multi-tasking lighting solutions? I am researching this myself but am keen to hear your opinions as you have already completed a similar project, albeit that you were installing a workshop which obviously requires a different lighting solution! It's an awkward one, because I want to be able to install the cabling now that would be suitable for any lighting installation that will eventually be chosen and as it's only cable, I'm not too bothered about over-compensating! Hmm. I think I'd lose patience with that, I often do  Personally speaking, I am quite left-brained with the exception of music. Visually, I know what I like and what I don't, and would far rather see a limited set of choices and work from those than be bombarded with 20 choices. Three is usually the number of ideas I put up, and then I have to try and discourage the client from using an element from each, to create a hybrid which never hangs together! Definitely. It doesn't mattter if the odd sheet is slightly dinged, even. You can cut that out. I didn't bother because I was able to get a reasonable price for all the project materials from Jewsons. Yeah, I suppose it depends on the final price you get for new when compared to used. I'm quite confident that Magnet will come up trumps as I have a good contact within that firm and he has assured me that I'd have to look hard to find a better price for sheet materials as they have decided to stock them at a ridiculously low price, in order to get the punters in so they can sell them a kitchen or bedroom! My local Magnet is currently offering 8x4 sheets of 15mm plasterboard at £3.15 per sheet... that's cheaper than B&Q's price for a sheet half that size! The sheet price also comes down for bulk orders! A couple of other questions I have a As I intend to split the space into two separate areas, should I redo my previous calculations treating each room completely separately and how do I factor in the heat-loss of the stud wall between the two spaces? How would that then affect the heating installation that I opt to go for? Would it just be a matter of installing a certain wattage of heater(s) in the office space to meet the optimum temperature of that environment and then install an arrangement of differently powered heaters in the workshop to achieve the desired temperature there? Is there a heating system that would provide both the heating and the air-change facility that would be required for the building? Maybe there's a product that does this and also provides air cooling/conditioning during the summer months! Any pointers would be appreciated, I don't expect you to all the answers, but as I said, it appears that you have "been there" as it were! Also, when estimating the amount of Celotex and plasterboard required, is there a percentage that I should account for with regards to wastage? I'm a bit worried about over/under-ordering! I'd also like to just say thank you at this point, your assistance and advice is very much appreciated. rgds Dean. |
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On Sat, 6 Nov 2004 23:24:08 +0000 (UTC), DeanoH
wrote: Andy Hall wrote: If you were looking at Building Regulation compliance, it would be a different story, but for this it's good enough. Yep. You may want to think about what temperatures and patterns of use as well. If you were constructing the building to meet Building Regulations, there are guidelines for each element and the approach is called the elemental method. You can read more about it in the Approved Document to Part L1 on www.odpm.gov.uk Basically there are maxima for each component that are allowed if you are in a situation where the building, by size, location, use etc. is controlled by the Building Regulations. In that case you would have had to make an application to the local authority and they would inspect your work. If you are not required to work to Building Regulations because the building is exempt, (you can look on any local authority web site for information on this or again on the ODPM site), then insulation is up to you. Since you are paying, then you have to do the trade off between insulation capital cost and the cost of running the heating. If you are using a more expensive fuel like electricity, then you will probably want to spend more on insulation. I would sit down and think about expected use patterns the year round - for example will you want to trudge down there when it is ****ing with rain horizontally? The go from there. If in doubr, it probably pays to err towards more insulation now, because it will be a pain to add later. The office part of the building will probably be used constantly, come rain or shine (or snow!), and I can also see me being in there until late at night on some occassions, such is the nature of the design business. The workshop part probably won't be used as much... maybe once or twice a week. OK, so you may want to think in terms of fan heaters or something like that, but I am not sure that there is much of a purchase cost saving vs. e.g. wall mounted oil filled radiators. Either way, insulation is important, even if the workshop is rarely used. Exactly. You can pick a given size of Celotex and work out the heat loss for the building at given temperatures. How does the result of the equation I worked out in my previous post (1809.2W) indicate which heating solution and output rating I would need, to maintain the target temperature inside the lodge? I know I might be jumping the gun a bit here as I have yet to allow for air- change, but I was just wondering! See below/ One part of the exercise is to ensure that you put in enough heating to reach the temperatures you want inside for the coldest outside. The other is to do the cost trade off. To do that one, you can look at average monthly temperatures, take the predicted use pattern for that month and hence the energy use and cost based on that outside temperature. You have to decide on what the pattern of use is, though. As above, constant use for the office but not for the workshop. OK, so you've used 18 degrees as the temperature difference from inside to outside. That would mean that if it drops to -3 outside, you would have +15 inside which might be OK for a workshop but a bit chilly for sitting around. The typical inside (lounge) temperature used for design purposes is +21 degrees, so the temperature difference is then 24 degrees. If you wanted to achieve that, then you would need to multiply your figure by 24/18 which is approximately 2.4kW That's where my maths lets me down! I would have recalculated the whole thing again using the new value of 24°! I assume that multiplying my result of 1,809.2W by 24/18 saves me doing that and gives me the same result? (Rhetorical question, as I'll try this offline!). In other words, when it's -3 outside, a 2.4kW heater would maintain 21 degrees inside. Ah! So this answers my question above about the relationship between the result of the calculations and the heating output required? Apart from factoring in the air-change, of course! Don't be surprised if this doubles the heat loss if you use the typical room air change numbers. There is also one more component that should be taken into account. You won't want to have a hermetically sealed box, so some air change needs to be included. To calculate this, you need to take the volume in cubic metres and multiply by 0.33 and the temperature difference again. This would give you the heat requirement to cover one air change per hour. However, the normal design criterion for a living room, games room etc. is 1.5 air changes per hour, so to do the whole lot it would be Volume x 0.33 x 1.5 x temperature_difference. Answer again is in Watts and you add that in. It could be as much heat as for the loss through the walls or even more. Undertood! I'm not quite sure how to calculate the volume in the roof space... if the pitch of the roof was 45°, I could just flip one side through 180° at the apex and treat it as a rectoid (???), but it's not 45°... I'll have to google this one! Calculate the area of the two right angled triangles forming the roof shape and multiply by the length of the section of the building.. Let's say your rafters are 500-600mm apart. You could cut the Celotex about 3-5mm oversize and it will squash in with a friction fit. If it's at size or slightly less, you tape them to the rafters with foil tape. Yep, a good friend of mine suggested using the tape, even if the interference fit is right... he said it helps when tacking the walls. One other thing is to not to forget to put some vents to the outside from behind the Celotex. When I did my workshop project, I used soffit vents (round plastic vents with a grille to keep out insects) that fitted into holes drilled under the eaves, one between every pair of rafters each side. You can put them in a different position, but ventilation is important. I was wondering what to do about this, there are currently no soffits in place and the space between the rafters is just open! I was thinking about sourcing some kind of mesh material that would allow the through- flow of air, but not insects! Is there a product that you can think of that would be suitable for this or is the only realistic option to fit wooden soffits and then cut holes between each rafter and fit soffit vents? If there was something that I could employ which was already perforated, then this would save time and a little money! Something like pegboard, but with smaller holes! Any ideas? Builder's merchants have various kinds of vents with fine mesh that you could probably use directly or suitably cut. Another thing that I did was to coat the inside wood surfaces with clear Cuprinol solvent based wood preservative before putting in the Celotex and covering over. Were your timbers tannelised? Would you recommend this even if they are? No they weren't apart from those in contact with the concrete base. If they are then there's no need, but remember to treat the ends with preservative, plus any other incidental pieces of non tanalised timber. While I think of it, it's important to wear a face mask when cutting tanalised wood as the dust can be harmful. Also, at this stage, have a think about the electrics. If you want to hide them and use flush mount fittings, then a good way is to put in conduits and outlet back boxes and to then run PVC singles wiring to connect them together. I went for function over form and used three compartment trunking everywhere, surface mounted. This allows me to add things as I go or if necessary move them without disrupting the walls. That's really the stage I'm at now! I have the cable and the pattress boxes and I came to an abrupt hault because I obviously need to run a separate ring main for the electrical heating if that was what I going to go for! This got me thinking about the heating, and then the insulation and then hence the start of this thread! This can be a good reason to install trunking. You can change your mind and add without upsetting the decorative work. I have recently completed some fairly major renovations to the house, in that we had the rear left corner of the house removed downstairs, so that we could extend our tiny kitchen to take up some of the space at the back of my garage (what a difference it has made, but that's another story!). One of the things I learnt during this, as I was pretty hands on with the project, was to set noggins between the studs at a height which matched the desired position of the wall sockets. The noggins were set back at such a distance from the front of the studs, so that when the pattress boxes were attached to the noggins, they would protrude slightly proud of the innermost face of the studs. This meant that when the plasterboards were offered up, a swift bash of the boards, around the area of the pattresses, would result in an impression of the corners of the wall boxes being left in the back of the plasterboard... the perfect template! Although you probably know that little trick already! Anyway, this is what I intend to do in the lodge. I'm just not yet sure whether to position the mains ring at skirting board height (or just above) or to run it round at desk height! What did you do? What pros and cons did you consider? I'm thinking desk height would keep the ring above any potential dampness and would permit easier access via a cable tray at the back of the desks or some such device. I did consider the conduit route, but that proved fairly expensive when I used it at a previous office premises! Do you think the trunking within the walls would really be necessary? I know it is probably part of the "perfect build" which your project sounds like it definitely was, but, while not wanting to cut too many corners (where it matters), cost is a major issue for me and I need to save where I can! For the workshop the three-compartment trunking is at about 1200mm above the floor. This was deliberately chosen to be at a convenient height to plug in machinery and not to be likely to be hit by wood being worked at bench height. It seems to work well. I used the same thing for the cabin. There is a small table space in that and the trunking ends up above that. For my study, I ran the trunking at just below desk height and then cut and fitted for cable management ports in the desk. This seems OK as well. I see no reason not to go for skirting level if you prefer though. This was all surface mounted trunking. In the workshop and cabin, I don't care if it's on view as function is more important than form. In the study, it's hidden away by being below desk level. If you want to run cables below the surface, and you think that you might want to change things then some trunking is a good idea. If you don't want to pay for the three compartment stuff, then you could put in square plastic trunking, say 50mm square below the wall surface and use that. This is a lot cheaper than the three compartment version. If you are certain that you won't make changes, then you can simply run in the wires. On the subject of electrics, I'm still quite unsure of what lighting fixtures to install in the building. Lighting is, and always has been, a major issue for me. I have always hated dingy rooms! And I don't want to end up with a harshly lit space! I want to create some mood lighting (for the creative looke/feel) and some task lighting for when working on the computers while referencing paperwork on the desktop. I obviously want to avoid screen glare and above all, not end up spending an absolute fortune on the installation, which I am apt to do when it comes to lighting... it's one of my weaknesses Have you any experience on this subject? Do you know of any products on the market that provide multi-tasking lighting solutions? I am researching this myself but am keen to hear your opinions as you have already completed a similar project, albeit that you were installing a workshop which obviously requires a different lighting solution! It's an awkward one, because I want to be able to install the cabling now that would be suitable for any lighting installation that will eventually be chosen and as it's only cable, I'm not too bothered about over-compensating! Well..... I am pretty sure that you are going to be more experienced on this than I am or have contacts who will know. For my study, I have used mainly halogen desktop lamps as this suits me and makes it easier to prevent screen glare. I can also point them at the walls and bounce light for a general glow if I like. For this situation, I have avoided any kind of fluoresecent or low energy lights because I generally don't like them except in specific circumstances. For the workshop which is mainly for wood working, I have painted the walls white and then installed a fairly high density of high frequency fluorescent fittings with different types of tube. I won't use fluorescent lighting without high frequency ballasts because I am sensitive to the flicker of ordinary fittings. It also avoids strobe effects with machines. I try when possible to use daylight as well. I switch on the appropriate amount of lighting in the places where I need light and in the amounts required. If you ar euncertain, you could install conduit boxes with covers in the ceiling and then wire as appropriate. Again I think it's future planning. Hmm. I think I'd lose patience with that, I often do Personally speaking, I am quite left-brained with the exception of music. Visually, I know what I like and what I don't, and would far rather see a limited set of choices and work from those than be bombarded with 20 choices. Three is usually the number of ideas I put up, and then I have to try and discourage the client from using an element from each, to create a hybrid which never hangs together! Definitely. It doesn't mattter if the odd sheet is slightly dinged, even. You can cut that out. I didn't bother because I was able to get a reasonable price for all the project materials from Jewsons. Yeah, I suppose it depends on the final price you get for new when compared to used. I'm quite confident that Magnet will come up trumps as I have a good contact within that firm and he has assured me that I'd have to look hard to find a better price for sheet materials as they have decided to stock them at a ridiculously low price, in order to get the punters in so they can sell them a kitchen or bedroom! My local Magnet is currently offering 8x4 sheets of 15mm plasterboard at £3.15 per sheet... that's cheaper than B&Q's price for a sheet half that size! The sheet price also comes down for bulk orders! A couple of other questions I have a As I intend to split the space into two separate areas, should I redo my previous calculations treating each room completely separately and how do I factor in the heat-loss of the stud wall between the two spaces? Since you are going to use the workshop rarely, then I would do the sums for the office space and then treat the partition wall as being an exterior one. There won't be quite as much heat loss as is implied by that, but that is not too important. For the opposite situation, if you think the office will be heated while the workshop is in use then treat the party wall as not existing. If it won't be, then treat as an exterior wall as before. How would that then affect the heating installation that I opt to go for? Would it just be a matter of installing a certain wattage of heater(s) in the office space to meet the optimum temperature of that environment and then install an arrangement of differently powered heaters in the workshop to achieve the desired temperature there? Exactly. Simply think about the likely patterns of use. Is there a heating system that would provide both the heating and the air-change facility that would be required for the building? Maybe there's a product that does this and also provides air cooling/conditioning during the summer months! Any pointers would be appreciated, I don't expect you to all the answers, but as I said, it appears that you have "been there" as it were! I was thinking this. You can get air conditioners which also heat pumps. In effect what these can do is to also operate in "reverse" and transfer heat from outside (even when it's cold) to the inside. These could contribute some or maybe even all of your heat. You need to study carefully though and look at the difference between the ratings in terms of energy used and energy transferred. Also, when estimating the amount of Celotex and plasterboard required, is there a percentage that I should account for with regards to wastage? I'm a bit worried about over/under-ordering! With Celotex, in effect, unless it's damaged because you bought seconds or something, then the wastage *can* be zero. However, you will probably find that you have odd triangles and trimmings left which are too small to be used in another section. Plasterboard is usually pretty cheap. If you are going to have it skimmed with plaster then you can probably get away with smaller pieces. Probably it isn't worth it though. I'd also like to just say thank you at this point, your assistance and advice is very much appreciated. You're very welcome. rgds Dean. -- ..andy To email, substitute .nospam with .gl |
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