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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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A loft hatch, joist cutting challenge for you...
Hi - I'm after some structural joist cutting type advice and figured
this would probably be a good starting point! :-) First of all, I'm very confused by the structure of our 1900's terraced flat so I've taken some pictures to accompany this post which I hope will help! Basically, I want to fit some (rather substantial) loft ladders however I'm a bit stuck when it comes to locations for them and am left with little alternative but to run them perpendicular to the joists. The opening required for the ladders is 120 x 70cm (47 1/4" x 27 1/2") and the ceiling joists are 12" apart (12" gap that is). The joists are 2 1/2" x 2 1/4" by the way. Unfortunately this means cutting 3 joists in order to fit them in! (see http://www.pciq.co.uk/pics/newopening.jpg - new hole marked in red). Now that wouldn't bother me too much if it wasn't for two things:- 1. Our ceiling joists appear to be held up by 1x1" bits of wood nailed to 1x4" bits of wood which are somehow attached to the walls (see http://www.pciq.co.uk/pics/joistends.jpg - I'm sure I'm missing something here but see for yourself!) 2. There would appear to be a large king post (11' high) supported by two 2x7" joists held together in the middle somehow which look like they're resting on our ceiling joists (see http://www.pciq.co.uk/pics/kingpost.jpg) There are NO load bearing walls in our flat (other than the outside walls of course) so can anyone explain the structure of our house? Anyway, my plan was to basically cut the three joists to create the opening and install some new 2 1/2" x 4" joists to support the cut joists - these would be morticed and screwed together for extra strength. This is much easier explained if you look at this:- http://www.pciq.co.uk/pics/plan.gif Yellow = new opening Black = ceiling joists Blue = new 2 1/2 x 4" joists Brown = 2x7" joists (spanning 30') Red = King post (11' high) So basically, the profile of the new joists (shown in blue) would be like this: http://www.pciq.co.uk/pics/profile.gif My only concern here is that the entire weight of the ceiling, the loft ladder (and people on the loft ladder), the contents of the loft and potentially the king post would be supported by the bits marked 'A' on plan.gif. Should I extend the 'Blue' supports out further (to the next set of joists either way) to spread the load? My only concern is that it would potentially weaken even more joists by morticing into them. Should I be concerned? Should I employ the services of a structural engineer? Should I sell my loft ladders? As a side note to all this, does anyone know why we appear to have ready made joist holes in our walls above the ceiling joists? (see http://www.pciq.co.uk/pics/joistholes.jpg and http://www.pciq.co.uk/pics/joisthole.jpg) Thanks for taking the time to read this epic - I look forward to ANY responses!! Cheers, Andy |
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#2
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#3
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Cheers for the replies! Comments below...
If your joists are only a bit bigger than 2 x 2, they're only capable of holding themselves plus the ceiling up - and I certainly wouldn't want to store anything other than empty cardboard boxes on top of them! Bugger. A cinema room with sofas, people and various other heavy stuff would be out of the question then? :-( Some of your pictures seem to suggest that the joists are not all at the same level - implying that the ceilings slope. Is this the case? -- Cheers, Set Square No - they're all at the same level - must just be my dodgy pics. To summarise, the loft area is 20' x 30' and there are two beams (effectively splitting the loft into three 30' x 6.6' sections) with king posts running from back to front (30' stretches) - these are 2x7" beams joined together in the middle somehow (double sided sticky tape?). The ceiling joists run left to right (20' streches - broken up by the chimney in the middle) - these are 2.5 x 2.25" joists with a gap of 12" between each. The loft feels VERY sturdy to walk on (nothing really happens when you jump up and down on the joists) but I still don't really understand how?!? Anyhoo... I've just spoken to a structural engineer and he reckons the ceiling joists will be held by the king post beams somehow - don't quite understand this. Anyway, getting him to come out and have a look, which is probably a good idea. Any more advice would be greatly appreciated though! :-) Cheers again, Andy |
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#4
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What depth are the current ceiling joists?
2.5" THe way in which the post meets the joists and the two ends of the ceiling joists "fly past" each other would suggest there is a supporting wall or some other load bearing structure under there. Nope - nothing underneath that one - just empty space! The other one (next to the chimney breast) might be supported by part of the chimney breast - haven't checked that yet... There are NO load bearing walls in our flat (other than the outside walls of course) so can anyone explain the structure of our house? How do you know the wall are not load bearing? (a stud wall can be load bearing as well - it does not need to be brick / block). There are certainly no internal brick / block walls other than the chimney breast and all the stud walls seem to run in directions which would offer little or no support to the ceiling joists... I could be wrong though - no expert on such things. :-) If there really is no load bearing wall, is there a substantial joist at the apex of the roof? Not really - the joist spanning the apex looks pretty small - I've taken some more pics which I hope will help: http://www.pciq.co.uk/pics/apex.jpg (ignore the damp - that's on the to-do list!). This one gives a better 'overall view' of the loft: http://www.pciq.co.uk/pics/loft.jpg I don't think I'm going to have much option but to add some extra joists to strengthen the floor in my 'storage area' - these could potentially attach to joist hangers in the wall and rest on the main 30' beams spanning from front to back, which I presume are currently supporting pretty much everything. The trouble there is that my floor will now be around 10" higher which means I'll lose quite a bit of loft space - such is life though. As you say, I don't think I've got much option but to strengthen the supporting joists for the stringer beam which will in-turn support the loft hatch. I certainly couldn't fit the hatch any higher (in new joists) since I'm already at the max floor to ceiling height (2.9m)... if that makes sense. Still don't really understand how my ceiling's held up... ....and anyone have any ideas on the existing 'joist sized holes' in the walls?? Cheers again! Andy |
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#6
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Ah. That gives another clue! The vertical beam you will note has much
more substantial rafters each side than all the others. It also has a pair of stays from those rafters to the base of the beam. Don't know if it makes any odds, but those 'big rafters' seem to be supporting larger beams (spanning the full width of the loft and held in the brickwork at either side) which in turn support the main rafters. Could we have a photo of how those stay beams (i.e. the diaglonal ones that run between A abd B or B and C in my diagram above) attach to the rafters? Don't have a photo of that bit (not yet anyway), but they're basically diagonally notched in, similar to how they're attached to the king post: http://www.pciq.co.uk/pics/kingpost.jpg The 'notch' side is at the bottom, if that makes any sense at all. to ceiling height (2.9m)... if that makes sense. Floor to ceiling height on the landing for the loft ladder? Yup. Nope - might have been used for temporary support of timbers while the place was being built? That's the only thing I can think of - very conveniently placed for a brand new floor me thinks... :-) Andy |
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#7
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wrote:
Ah. That gives another clue! The vertical beam you will note has much more substantial rafters each side than all the others. It also has a pair of stays from those rafters to the base of the beam. Don't know if it makes any odds, but those 'big rafters' seem to be supporting larger beams (spanning the full width of the loft and held in the brickwork at either side) which in turn support the main rafters. It could be the other way round. You have beams that run the full width of the loft that are fixed into the brickwork at either end. These support the pair of "A" frames, the A frames susspend the central floor joists. These floor joists in turn carry the other floor joists. (its times like this one of those 3D walkaround pictures would come in handy ;-) That's the only thing I can think of - very conveniently placed for a brand new floor me thinks... :-) I would not worry about the existing holes - compared to the task of adding a new floor, having two holes available is not going to make much impact on the total scale of the work. If you need to fix beams to the wall these can be hung from a heavy shoe that is bolted to the wall:- (In true Blue Peter tradition - here is one I made earlier) http://www.internode.co.uk/temp/shoe.jpg That is the left hand end of beam F as shown on this plan view:- http://www.internode.co.uk/temp/beam-layout.gif -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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#8
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Er, my guess is that the "King Post" and the other timbers joining it
make a truss which supports the roof - the rafters resting on wall plate and ridge with one or two purlins in between. Where the horizontal truss timbers overlap they are almost certainly firmly bolted together. So the whole roof+truss are independant of the ceiling joists which may be removed however you want. The 2 ceiling joists which cross the end of the proposed opening would need strengthening as they would carry the extra load of the ceiling no longer supported by the removed joists. Perhaps double up with a new timber on top bolted through in several places. cheers Jacob |
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#9
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jacob wrote:
Er, my guess is that the "King Post" and the other timbers joining it make a truss which supports the roof - the rafters resting on wall plate and ridge with one or two purlins in between. Where the horizontal truss timbers overlap they are almost certainly firmly bolted together. Yup, sounds likely to me. So the whole roof+truss are independant of the ceiling joists which Independant in the sense that the foor structure will not be affected by what you do to the floor, however related in that the truss structure also supports the floor. may be removed however you want. The 2 ceiling joists which cross the end of the proposed opening would need strengthening as they would carry the extra load of the ceiling no longer supported by the removed joists. Perhaps double up with a new timber on top bolted through in several places. I think something will need to be done to strengthen the whole area if much use is going to made of it for storage, since 2 1/2" timber is not going to be that much for se other than holding itself and the ceiling up. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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#10
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OK, cheers again for the replies. I spent another day in there
clearing crap out over the weekend (is 28kg of lead piping worth anything? :-) ). Having hoovered out 11 bags of dust in the area of the proposed opening, it's all making a lot more sense now, although I can't say I've ever seen anything like it before! I've taken a couple more pics to explain... For starters, here's a scale plan and elevation of the loft (Visio is really starting to do my head in for this sort of stuff - can anyone recommend a more 'appropriate' package for plans, elevations and (if pos) 3D views?):- http://www.pciq.co.uk/pics/loftplan.gif http://www.pciq.co.uk/pics/loftelev.gif (the current and proposed openings can be seen on the right of the plan - I haven't bothered to show the joists, but needless to say they span left-to-right (perpendicular to the main beams) and, as mentioned, are 12" apart) The main beams spanning the full loft are indeed bolted together in two places, as can be seen he- http://www.pciq.co.uk/pics/joistbeam.jpg This is how the principal rafters notch into this main beam:- http://www.pciq.co.uk/pics/praftbeampur.jpg This is another view of the ridge board and principal rafters notched into the king post:- http://www.pciq.co.uk/pics/ridgekp.jpg ....and this is how the purlins are notched into the principal rafters - also showing the struts notched into the principal rafters:- http://www.pciq.co.uk/pics/praftstrtpur.jpg ....and a close up of the latter:- http://www.pciq.co.uk/pics/strutpraft.jpg ....and the ceiling joists nailed into the main beam:- http://www.pciq.co.uk/pics/joistbeam2.jpg So, by my understanding the ceiling joists are simply nailed into the walls and beams in 6-7' sections, like this:- http://www.pciq.co.uk/pics/joistevelwl.gif http://www.pciq.co.uk/pics/joistelevbm.gif ....and if this is the case, no matter how sturdy it currently feels, there's no way on earth I'm putting any weight on the existing ceiling joists. New floor it is then! :-) I would not worry about the existing holes - compared to the task of adding a new floor, having two holes available is not going to make much impact on the total scale of the work. If you need to fix beams to the wall these can be hung from a heavy shoe that is bolted to the wall. I was planning on using joist hangers mortared into the brickwork as opposed to the 'bolt in' type since I've tried drilling these bricks and they're like solid steel. Anything to avoid drilling 80 x 10mm (or whatever) holes would be a bonus! Anyone have any experience of using these? I was planning on using the Catnic 50x150 ones from Screwfix, although (as yet) I have no real clue of how many joists I'm putting in, how far they'll be apart or how big they'll be... I'm also trying to decide whether to... 1) Simply install the joists in 2 x 3.6m sections bolted together in the middle (suspended above the existing beams) - spanning the 6.3m width, that would give a 0.9m overlap for bolting... OR 2) As above, but notch them into the main beams. OR 3) Install joist hangers between the main beams and the walls. I.e. the sections closest to the walls would be supported by the brickwork and the main beams. The section in the middle would just be supported by the main beams. Option 1 would obviously be better for noise since the loft floor would be totally isolated from the ceiling, however it would add quite a bit of height to the floor. Option 2 would save a couple of inches of floor height and would share the load between the walls and beams, thereby reducing bounce in the middle (I presume) - however noise isolation wouldn't be as good. Option 3 would probably be the easiest but places much more load on the main beams which (although seem to be incredibly sturdy) probably aren't designed to support a floor. ??? Any other ideas? A structural engineer is kindly popping 'round to check the situation out in a couple of hours, so doubtless I'll come back with a whole different plan... :-) Cheers again, Andy |
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#11
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Option 1 would obviously be better for noise since the loft floor would
be totally isolated from the ceiling, however it would add quite a bit of height to the floor. A quick play with SuperBeam in my unskilled hands suggests that a 6.3m span would require either (assuming that you want a proper floor later suitable for conversion). Assuming 30cm joist spacing: a) 30mm x 300mm wooden joists or b) various steel sections such as i) 100x100x8 square hollow section (thinnest) ii) 160x80x4 rectangular hollow section (lightest) iii) 178x102x19 universal beam (easiest to find) The taller steel sections would have much less deflection than the wood, whilst the 100 SHS solution is similar. Your building control officer or structural engineer can make more accurate calculations. Christian. |
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#12
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In an earlier contribution to this discussion,
wrote: OK, cheers again for the replies. I spent another day in there clearing crap out over the weekend (is 28kg of lead piping worth anything? :-) ). Having hoovered out 11 bags of dust in the area of the proposed opening, it's all making a lot more sense now, although I can't say I've ever seen anything like it before! I've taken a couple more pics to explain... For starters, here's a scale plan and elevation of the loft (Visio is really starting to do my head in for this sort of stuff - can anyone recommend a more 'appropriate' package for plans, elevations and (if pos) 3D views?):- http://www.pciq.co.uk/pics/loftplan.gif http://www.pciq.co.uk/pics/loftelev.gif (the current and proposed openings can be seen on the right of the plan - I haven't bothered to show the joists, but needless to say they span left-to-right (perpendicular to the main beams) and, as mentioned, are 12" apart) The main beams spanning the full loft are indeed bolted together in two places, as can be seen he- http://www.pciq.co.uk/pics/joistbeam.jpg This is how the principal rafters notch into this main beam:- http://www.pciq.co.uk/pics/praftbeampur.jpg This is another view of the ridge board and principal rafters notched into the king post:- http://www.pciq.co.uk/pics/ridgekp.jpg ...and this is how the purlins are notched into the principal rafters - also showing the struts notched into the principal rafters:- http://www.pciq.co.uk/pics/praftstrtpur.jpg ...and a close up of the latter:- http://www.pciq.co.uk/pics/strutpraft.jpg ...and the ceiling joists nailed into the main beam:- http://www.pciq.co.uk/pics/joistbeam2.jpg So, by my understanding the ceiling joists are simply nailed into the walls and beams in 6-7' sections, like this:- http://www.pciq.co.uk/pics/joistevelwl.gif http://www.pciq.co.uk/pics/joistelevbm.gif ...and if this is the case, no matter how sturdy it currently feels, there's no way on earth I'm putting any weight on the existing ceiling joists. New floor it is then! :-) I would not worry about the existing holes - compared to the task of adding a new floor, having two holes available is not going to make much impact on the total scale of the work. If you need to fix beams to the wall these can be hung from a heavy shoe that is bolted to the wall. I was planning on using joist hangers mortared into the brickwork as opposed to the 'bolt in' type since I've tried drilling these bricks and they're like solid steel. Anything to avoid drilling 80 x 10mm (or whatever) holes would be a bonus! Anyone have any experience of using these? I was planning on using the Catnic 50x150 ones from Screwfix, although (as yet) I have no real clue of how many joists I'm putting in, how far they'll be apart or how big they'll be... I'm also trying to decide whether to... 1) Simply install the joists in 2 x 3.6m sections bolted together in the middle (suspended above the existing beams) - spanning the 6.3m width, that would give a 0.9m overlap for bolting... OR 2) As above, but notch them into the main beams. OR 3) Install joist hangers between the main beams and the walls. I.e. the sections closest to the walls would be supported by the brickwork and the main beams. The section in the middle would just be supported by the main beams. Option 1 would obviously be better for noise since the loft floor would be totally isolated from the ceiling, however it would add quite a bit of height to the floor. Option 2 would save a couple of inches of floor height and would share the load between the walls and beams, thereby reducing bounce in the middle (I presume) - however noise isolation wouldn't be as good. Option 3 would probably be the easiest but places much more load on the main beams which (although seem to be incredibly sturdy) probably aren't designed to support a floor. ??? Any other ideas? A structural engineer is kindly popping 'round to check the situation out in a couple of hours, so doubtless I'll come back with a whole different plan... :-) Cheers again, Andy What a fascinating structure! Thanks for sharing it with us. I agree with you that, the way the joist are supported, they are clearly only designed to hold up the ceiling - which appears to be lath and plaster, which is heavier than plasterboard, anyway. With regard to bolting joist hangers to the walls, have you tried using a good SDS drill - that should go through hard brick quite easily! Good luck with your structural engineer. -- Cheers, Set Square ______ Please reply to newsgroup. Reply address is invalid. |
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#13
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wrote:
First may I congratulate you on a very well put together posting and synopsis! Makes it so much simpler to work out what is going on. OK, cheers again for the replies. I spent another day in there clearing crap out over the weekend (is 28kg of lead piping worth anything? :-) ). Having hoovered out 11 bags of dust in the area of Only if you take it to a scrap yard yourself... and then not that much. For starters, here's a scale plan and elevation of the loft (Visio is really starting to do my head in for this sort of stuff - can anyone recommend a more 'appropriate' package for plans, elevations and (if pos) 3D views?):- I often ask myself that - there must be a package that is more oriented toward building plans and layouts without going to full blown CAD. When you find it let me know! The main beams spanning the full loft are indeed bolted together in two places, as can be seen he- http://www.pciq.co.uk/pics/joistbeam.jpg OK - the previous deduction regarding trusses seems like it is about right then. The two trusses hold the two big beams, they carry the ceiling. ...and the ceiling joists nailed into the main beam:- http://www.pciq.co.uk/pics/joistbeam2.jpg Lath and plaster ceiling - will reduce noise transmission a bit more than plasterboard, but less likely to have acceptable fire performance if doing a conversion. Not a big problem though. So, by my understanding the ceiling joists are simply nailed into the walls and beams in 6-7' sections, like this:- http://www.pciq.co.uk/pics/joistevelwl.gif http://www.pciq.co.uk/pics/joistelevbm.gif ...and if this is the case, no matter how sturdy it currently feels, there's no way on earth I'm putting any weight on the existing ceiling joists. New floor it is then! :-) The truss design and beams it carries do indeed look strong. If they are upto carrying a complete floor however is another matter. The ceiling beams however look far less sturdy. I was planning on using joist hangers mortared into the brickwork as opposed to the 'bolt in' type since I've tried drilling these bricks and they're like solid steel. Anything to avoid drilling 80 x 10mm (or whatever) holes would be a bonus! Anyone have any experience of using these? I was planning on using the Catnic 50x150 ones from Screwfix, The "mortar in" types are really designed to be built into the wall rather than added afterwards. Treat yourself to a nice SDS drill and the bricks will loose any abilty to fight back! although (as yet) I have no real clue of how many joists I'm putting in, how far they'll be apart or how big they'll be... Usual spacing for a floor is 400mm centre to centre. The trickey bit is that you have no central supporting wall (hence the unusual design of the roof). So the spans in either direction are rather long. I would expect the simplest way would be one substantial beam (probably a RSJ) right through the middle of the loft to which you can then attach new floor beams (ther other end resting on the wall plate). So in plan you get:- ##################### - back wall | | | | | | | | | | | | | | | | | | | | | - new floor beams | | | | | | | | | | | | | | *===================* - new RSJ | | | | | | | | | | | | | | | | | | | | | - new floor beams | | | | | | | | | | | | | | ##################### - front wall If you wanted to clear the space in the loft you would need to do away with those king posts. The existing ceiling could be supported from the new floor if required, and the large rafters could probably be left in place since they mutually support each other. The struts that run from the rafters to the base of the king beam could be replaced with a pair of dwarf walls toward the front and back of the loft which would sit on the new floor - or you may find thay are not actually required at all if you remove the king post. 1) Simply install the joists in 2 x 3.6m sections bolted together in the middle (suspended above the existing beams) - spanning the 6.3m width, that would give a 0.9m overlap for bolting... That would rely on the existing stucture to carry the load. You would need your structural engineer to do some calcs to see if it is up to it. It also depends a little on wether we are talking about adding storage space, or actually doing a complete "floor" that would be suitable for a loft conversion. Option 1 would obviously be better for noise since the loft floor would be totally isolated from the ceiling, however it would add quite a bit of height to the floor. You look like you have a fair bit of height available. If converting (and say adding a rear dormer) that would make for a decent ceiling height even with the raised floor level. A structural engineer is kindly popping 'round to check the situation out in a couple of hours, so doubtless I'll come back with a whole different plan... :-) Let us know what he says - it will be interesting to get his take on it. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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#14
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Christian McArdle wrote:
A quick play with SuperBeam in my unskilled hands suggests that a 6.3m span would require either (assuming that you want a proper floor later suitable for conversion). Assuming 30cm joist spacing: a) 30mm x 300mm wooden joists Was that a typo? seems like a skinny joist! -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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#15
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In an earlier contribution to this discussion,
John Rumm wrote: wrote: For starters, here's a scale plan and elevation of the loft (Visio is really starting to do my head in for this sort of stuff - can anyone recommend a more 'appropriate' package for plans, elevations and (if pos) 3D views?):- I often ask myself that - there must be a package that is more oriented toward building plans and layouts without going to full blown CAD. When you find it let me know! For visual representations, I use a program called Floorplan 3D - which came on the cover disc of a recent PC Plus Magazine [Issue 213 - March 2004]. It's nothing like as dimensionally accurate as a proper CAD program, but it's very much quicker to knock up a reasonable 3D rendered picture of the outside of a building or of its internal structure. It does walk-throughs and also lets you selectively display layers so that, for example, you can see what it looks like with the roof removed. -- Cheers, Set Square ______ Please reply to newsgroup. Reply address is invalid. |
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#16
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a) 30mm x 300mm wooden joists
Was that a typo? seems like a skinny joist! Well spotted! That should be 50mm. Christian. |
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#17
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For starters, here's a scale plan and elevation of the loft (Visio is
really starting to do my head in for this sort of stuff - can anyone recommend a more 'appropriate' package for plans, elevations and (if pos) 3D views?):- I often ask myself that - there must be a package that is more oriented toward building plans and layouts without going to full blown CAD. When you find it let me know! The package I have used for years is a pencil, rubber, T square, drawing board, paper etc. I find its much quicker than any computer prog and a fraction of the price. The drawings are somehow much more readable too. Recently bought a posh board with parallel motion 2nd hand - only £40. so its even easier. cheers Jacob |
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#18
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"jacob" wrote in message
om... For starters, here's a scale plan and elevation of the loft (Visio is really starting to do my head in for this sort of stuff - can anyone recommend a more 'appropriate' package for plans, elevations and (if pos) 3D views?):- I often ask myself that - there must be a package that is more oriented toward building plans and layouts without going to full blown CAD. When you find it let me know! The package I have used for years is a pencil, rubber, T square, drawing board, paper etc. I find its much quicker than any computer prog and a fraction of the price. The drawings are somehow much more readable too. Recently bought a posh board with parallel motion 2nd hand - only £40. so its even easier. good lord, you'll be telling us you don't use a router and a fancy jig for mortises next ! ;-) -- Richard Sampson email me at richard at olifant d-ot co do-t uk |
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#19
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Well, cheers for all the replies and comments - I'm somewhat of a
newbie on this group but, as I've got an entire house (well, flat) to renovate, I can see me being quite a regular here! :-) I agree on the SDS front - think I'll have to find some room in the 'renovation budget' for one of those... been meaning to get one for a while now anyway. I would expect the simplest way would be one substantial beam (probably a RSJ) right through the middle of the loft Unfortunately (I didn't show this on any of the plans for simplicity) there's actually a bay window at the front of the house which may cause some problems for supporting an RSJ - not sure - another structural engineer question I think... If you wanted to clear the space in the loft you would need to do away with those king posts. Yeah - this would certainly be the preferred option since it would give me over 600 square feet of open loft space... which would be nice. The structural engineer (SE) suggested reinforcing the principal rafters with steel 'U' shaped strips, which may provide enough support to remove the cross-struts. Unfortunately he didn't want to guarantee this without modelling it though - same goes for the king post (see SE comments below)... That would rely on the existing stucture to carry the load. You would need your structural engineer to do some calcs to see if it is up to it. It also depends a little on wether we are talking about adding storage space, or actually doing a complete "floor" that would be suitable for a loft conversion. Yeah - again, SE territory as you say. Initially the plan was to just do the loft out for storage (we were going to get a full conversion done until we found every quote was coming back at =A320k+ - plus, with it being a flat, it would mean additional fire protection between the ground and first floor, which would be a major pain in the arse). So the plan now is to kit it out for storage initially with a view to turning it into some sort of cinema / music / toy room later down the line. So it would certainly make sense getting the floor sorted now... it also gives me something to do while waiting for planning permission etc. for some of our other projects. :-) [SE] Let us know what he says - it will be interesting to get his take on it. Well, here goes! Basically there's 3 stages to the whole project... 1=2E Fit the loft hatch The SE was confident the loft hatch could be fitted into the existing ceiling joists without compromising structural stability providing the supporting joists at either end are doubled up. 2=2E Fitting a 'floor area' for storage He was happy with a '1/6' section of the loft being devoted to storage however a new floor would be required in this area - this would need to be held in the wall by joist hangers on one side and rest on one of the 30' beams on the other... er, like this:- http://www.pciq.co.uk/pics/storage.gif It would require some structural calcs to ensure the beam can handle the weight, but nothing too major - he reckoned around =A3100-=A3150 for his time, and this would include specifying materials, design etc. 3=2E Full 'shell' conversion Finally, he quoted around =A3350-400 to model a full shell conversion - this would include removing all king posts and struts and putting a brand new floor in place. He's fairly certain this would involve a fair bit of steel work, but it would all be dependant on the computer modelling to work out the cheapest / easiest way of doing things. Just waiting to get the finalised quotes off him before proceeding - think we might just have to go for option 2 for the moment since, in the scheme of things, option 3 will be out of budget for now... at least until we get the rest of the flat finished. Not sure yet... Anyway, what do people know about soil pipes? :-) Andy |
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In an earlier contribution to this discussion,
wrote: Anyway, what do people know about soil pipes? :-) Andy What do you want to know? -- Cheers, Set Square ______ Please reply to newsgroup. Reply address is invalid. |
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wrote:
I would expect the simplest way would be one substantial beam (probably a RSJ) right through the middle of the loft Unfortunately (I didn't show this on any of the plans for simplicity) there's actually a bay window at the front of the house which may cause some problems for supporting an RSJ - not sure - another structural engineer question I think... I was thinking about the RSJ running side to side rather than front to back. The beams would then run front to RSJ and RSJ to back. Having the bay window may complicate it a bit since the lintel over it may not be up to the task of taking a floor load. I hade exactly the same issue to solve on my place. I used a flitch beam as a stringer just in front of the bay window lintel. That way I did not need to worry about if it would be up to the job. 2. Fitting a 'floor area' for storage He was happy with a '1/6' section of the loft being devoted to storage however a new floor would be required in this area - this would need to be held in the wall by joist hangers on one side and rest on one of the 30' beams on the other... er, like this:- http://www.pciq.co.uk/pics/storage.gif Look like a good plan. You could alternatively go for upto 4 smaller areas at each corner in the same way if you need to store heavier stuff (i.e. keeping it close to the edges) 3. Full 'shell' conversion Finally, he quoted around £350-400 to model a full shell conversion - Sounds fair... cost me 570 for full plans and calcs. least until we get the rest of the flat finished. Not sure yet... Anyway, what do people know about soil pipes? :-) Round, pipey and full of **it ;-) -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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#22
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"Set Square" wrote in message
... In an earlier contribution to this discussion, wrote: Anyway, what do people know about soil pipes? :-) Andy What do you want to know? -- Cheers, Set Square Sorry about the delay in replying - finally got a proper newsfeed working! :-) It's OK - think I've got the soil pipe thing sussed. Just needed to know if a 12m length with 3 x 90' bends would pass building regs. Turns out it's OK providing I have a stub stack with air admittance valve. Cheers anyway! Andy |
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