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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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Silocone injection damp proofing effective?
Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in my 1900-built house. (The damp can be detected up to about 4 feet above the floor). I suppose it could also be damp penetrating through from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Thank you Jake |
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"Jake" wrote in message
... Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in my 1900-built house. (The damp can be detected up to about 4 feet above the floor). I suppose it could also be damp penetrating through from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Would a house of that age even have cavity walls? Have you taken a look outside, and checked for things like leaking drainpipes, soil bridging the damp course (I don't know what they used in 1900), that sort of thing? (ie the basics.) More questions than answers, I know! Rick |
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"Richard Sterry" wrote in message ... "Jake" wrote in message ... Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in my 1900-built house. (The damp can be detected up to about 4 feet above the floor). I suppose it could also be damp penetrating through from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Would a house of that age even have cavity walls? have a look at the brick pattern of the walls, if it's the same as a modern house with bricks overlapping by fifty percent then it's likely it has a cavity, if as with mine it has one long edge of a brick followed by the short end of a brick (flemish bond) or layers of ends of brick over sides of brick( English bond) then it's likely you do not have a cavity. Also if there is no cavity then the wall will only be nine-ish inches thick whereas a cavity wall will be at least 11 inches TheQ snip |
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On Mon, 8 Nov 2004 17:04:17 -0000, "Richard Sterry"
wrote: "Jake" wrote in message ... Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in my 1900-built house. (The damp can be detected up to about 4 feet above the floor). I suppose it could also be damp penetrating through from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Would a house of that age even have cavity walls? Have you taken a look outside, and checked for things like leaking drainpipes, soil bridging the damp course (I don't know what they used in 1900), that sort of thing? (ie the basics.) More questions than answers, I know! Yes, it definitely has cavity walls. I've had to replace some bricks in it. Yes, there is an issue with rainwater gathering on the pavement outside to some extent, but I can't do much about that. Anyone got an answer to my original question? Jake |
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Jake wrote in message ... Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in my 1900-built house. (The damp can be detected up to about 4 feet above the floor). I suppose it could also be damp penetrating through from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Thank you Jake In my limited experience of *Real* serious rising damp, ( are you completely sure you do have *rising* damp?) silicone injection is a complete waste of time and money. Internally you will still need to remove all plaster/render upto 1.2 Mt and apply a water/salt proof render coat to the walls before you can re-plaster. By doing this you stand a far chance of pushing the damp somewhere else FWIW the fluid and the injection equipment can be hired from. http://www.hss.com A cheaper and more effective method however is this http://www.newton-membranes.co.uk/newlath.htm HTH -- Mark |
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Jake wrote:
Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in It is probably effective in the sense that it will introduce a damp proof layer in a wall. However whether that will cure your problem is a very different question. It would depend on why it is damp. my 1900-built house. (The damp can be detected up to about 4 feet Detected how? Have you drilled samples and tested for moisture content in the removed material, or just used an electrical resistance tester? above the floor). I suppose it could also be damp penetrating through The most common causes are "bridging" (i.e. soil/path level above DPC), broken down pipes/gutters etc. Lack of heating and ventilation (blocked air bricks, fitting DG windows and hence eliminating natural ventilation) inside the building and hence condensation. from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? It could well be a solid wall at that age. A slate layer would be a typical DPC for that age. Assuming there are not extensive cracks in the wall, how exactly does a bit of slate "fail". Does it cease to be slate? There is a possibility (although unlikely) that no DPC was ever installed, in which case adding one may help. If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Can't help you there - although I am sure the kit can be hired, and it will presumably work out much cheaper than getting a damp proofing company in to do the work. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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In article , "Jake" jake4445
@spamBgone.com says... On Mon, 8 Nov 2004 17:04:17 -0000, "Richard Sterry" wrote: "Jake" wrote in message ... Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in my 1900-built house. (The damp can be detected up to about 4 feet above the floor). I suppose it could also be damp penetrating through from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Would a house of that age even have cavity walls? Have you taken a look outside, and checked for things like leaking drainpipes, soil bridging the damp course (I don't know what they used in 1900), that sort of thing? (ie the basics.) More questions than answers, I know! Yes, it definitely has cavity walls. I've had to replace some bricks in it. Yes, there is an issue with rainwater gathering on the pavement outside to some extent, but I can't do much about that. If any of the pavement is yours then put a drainage channel in, if it's the council's then try to get them to do it. |
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In article ,
Jake wrote: Yes, it definitely has cavity walls. I've had to replace some bricks in it. In other words, the wall consists totally of stretcher bricks with no headers? Ie all the bricks are lengthwise with none end on? Yes, there is an issue with rainwater gathering on the pavement outside to some extent, but I can't do much about that. All the true cavity walls I've ever seen have a damp proof course. If you can't see it for some reason to be sure, then that needs to be addressed first. Anyone got an answer to my original question? On its own, a silicone damp course won't cure the problem. It has to be combined with a waterproof re-plastering of the inside. Which beggars the question as to whether the silicone does anything worthwhile at all. -- *42.7% of statistics are made up. Sorry, that should read 47.2% * Dave Plowman London SW To e-mail, change noise into sound. |
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John Rumm wrote in message ...
Jake wrote: Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in It is probably effective in the sense that it will introduce a damp proof layer in a wall. However whether that will cure your problem is a very different question. It would depend on why it is damp. my 1900-built house. (The damp can be detected up to about 4 feet Detected how? Have you drilled samples and tested for moisture content in the removed material, or just used an electrical resistance tester? above the floor). I suppose it could also be damp penetrating through The most common causes are "bridging" (i.e. soil/path level above DPC), broken down pipes/gutters etc. Lack of heating and ventilation (blocked air bricks, fitting DG windows and hence eliminating natural ventilation) inside the building and hence condensation. from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? It could well be a solid wall at that age. A slate layer would be a typical DPC for that age. Assuming there are not extensive cracks in the wall, how exactly does a bit of slate "fail". Does it cease to be slate? There is a possibility (although unlikely) that no DPC was ever installed, in which case adding one may help. If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Can't help you there - although I am sure the kit can be hired, and it will presumably work out much cheaper than getting a damp proofing company in to do the work. -- Cheers, John. I would caution the OP about this path of action. 1900 houses handle damp entirely differently from modern buildings, and dpc injection can result in the fabric of the building beginning to disintegrate near ground level. It is not suitable for Victorian buildings. Nor is it effective in such buildings, it hinders the damp control system more than it helps it. It seems to me you need to understand how your building deals with damp, and what things you can rectify. To speak with the experts, I'd suggest: http://www.periodproperty.co.uk/cgi-...rum2.pl?#34641 For other general interest, most Vic houses had no dpc of any kind, and there are indeed 9" thick cavity walls, its called ratbond. Vics with dpc usually used slate as the dpc material, and slate dpcs often become ineffective due to them being bridged on the outside with mortar. Of the few slate dpcs I've seen at least half were bridged by inappropriate repointing technique. However if this has been done, one should be wary of breaking the mortar off, since cement in sound condition is a lot stronger than slate. NT |
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In article ,
xavier wrote: The strict answer to your questions is Yes. But it won't do it by itself. An injection damp proof course is part of a system with the other part being the re-plastering. If you need the injection, you need the replastering! Which beggars the question as to what the silicone actually does? Apart from lining the pockets of the installer? -- *The e-mail of the species is more deadly than the mail * Dave Plowman London SW To e-mail, change noise into sound. |
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N. Thornton wrote:
I would caution the OP about this path of action. 1900 houses handle damp entirely differently from modern buildings, and dpc injection can result in the fabric of the building beginning to disintegrate near ground level. It is not suitable for Victorian buildings. Something else to remember when thinking about adding impermeable layers / coatings / membranes to walls etc, it that much of the flow of water through a wall is from the inside to the outside. So sealing it can make damp worse. -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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On Tue, 09 Nov 2004 01:55:17 +0000, John Rumm
wrote: Jake wrote: Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in It is probably effective in the sense that it will introduce a damp proof layer in a wall. However whether that will cure your problem is a very different question. It would depend on why it is damp. my 1900-built house. (The damp can be detected up to about 4 feet Detected how? Have you drilled samples and tested for moisture content in the removed material, or just used an electrical resistance tester? I used a resistance tester. Also, the wall was plastered with some very moisture-absorbent plaster. you could actually see the damp in the unpainted plaster (as a darker area) after I stripped the walpaper off. You could feel it by touching it too. above the floor). I suppose it could also be damp penetrating through The most common causes are "bridging" (i.e. soil/path level above DPC), broken down pipes/gutters etc. Lack of heating and ventilation (blocked air bricks, fitting DG windows and hence eliminating natural ventilation) inside the building and hence condensation. from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? It could well be a solid wall at that age. Its a cavity wall. I've eplaced bricks in the outer skin, etc. A slate layer would be a typical DPC for that age. Assuming there are not extensive cracks in the wall, how exactly does a bit of slate "fail". Does it cease to be slate? There is a possibility (although unlikely) that no DPC was ever installed, in which case adding one may help. It's really hard to ascertain if a DPC is even present because the outside of the house had ben rendered with some strong mortar. If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Can't help you there - although I am sure the kit can be hired, and it will presumably work out much cheaper than getting a damp proofing company in to do the work. I reckon it might be worth a try. The re-plastering of the interior is the biggest nightmae though. I just want to sell the house. I'm now thinking it might be better to sell the house at an appropriate price and let the buyer worry about it. Thanks for your input (and to everyone else too). Jake |
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In article ,
Jake wrote: It could well be a solid wall at that age. Its a cavity wall. I've eplaced bricks in the outer skin, etc. You can replace bricks in the outer skin of a 9" non cavity wall too. If you've had to replace bricks, what sort of condition is the pointing in? This is a primary cause of water soaking through a wall. -- *The older you get, the better you realize you were. Dave Plowman London SW To e-mail, change noise into sound. |
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Jake wrote:
Does anyone know if silicone injection damp-proofing is effective? I have what appears to be rising damp along the two walls of a room in my 1900-built house. (The damp can be detected up to about 4 feet above the floor). I suppose it could also be damp penetrating through from the outside skin of the cavity wall, if the cavity has some debris in it. Due to the 104-yr old age of the house, I guess it was built with a slate damp-prroof course if anything. Would silicone injection likely cure it - and if so, how long for? It IS effective IF the problem is rising damp. The comparisons between walls that had been injected and those that had not in my old house was startling. If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Get the boys in. Its easier. Thank you Jake |
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"Dave Plowman (News)" wrote in message ...
In article , xavier wrote: The strict answer to your questions is Yes. But it won't do it by itself. An injection damp proof course is part of a system with the other part being the re-plastering. If you need the injection, you need the replastering! Which beggars the question as to what the silicone actually does? Apart from lining the pockets of the installer? Yes, that's the popular conclusion but perhaps it misses the point. An injection dpc is a system which consists of two parts. The purpose of the injection is to control the damp and restrict it as far as possible. It's highly unlikely, even in ideal circumstances that it will completely stop the damp but, in conjunction with replastering, it will control the problem so that it becomes acceptable. Merely re-plastering a wall could have unforseen consequences such as (if there really is rising damp) encouraging it to rise even higher to the point where it's above the level of the new plaster. This phenomenon is quite distinctive and is an indication that an injection dpc has actually failed. The re-plastering not only stops any residual damp from migrating to the surface but it has another, and perhaps more important purpose which is to remove chlorides and nitrates which will have migrated to the surface of the old plaster. If they were left there then the wall would be forever hygroscopic and no matter what you did with injections, or physical dpc's for that matter, the wall would always be damp. The presence, or lack of, salts in a wall is sure indication of whether there's ground water (rising or penetrating) in it but unfortunately it's a diagnostic method which is eschewed by the dpc industry. It's much easier to stick a moisture meter into the wall, listen to it buzz and flash red and con the poor househoder into paying for an injection dpc to cure the condensation caused by the double glazing which was sold to them on the basis that it would cut draughts and create a pleasant atmosphere. It all brings on five o'clock wouldn't you say? KR's xav |
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On Tue, 09 Nov 2004 18:28:45 +0000 (GMT), "Dave Plowman (News)"
wrote: In article , Jake wrote: It could well be a solid wall at that age. Its a cavity wall. I've eplaced bricks in the outer skin, etc. You can replace bricks in the outer skin of a 9" non cavity wall too. I can tell you it's acavity wall. I've seen the cavity - when I installed an airbrick, etc. If you've had to replace bricks, what sort of condition is the pointing in? This is a primary cause of water soaking through a wall. The bricks I replaced were on an unrendeed side of the house. The side affected by damp is rendered. Jake |
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On Tue, 09 Nov 2004 23:03:01 +0000, Pete C
wrote: On Tue, 09 Nov 2004 18:06:52 GMT, (Jake) wrote: I used a resistance tester. Also, the wall was plastered with some very moisture-absorbent plaster. you could actually see the damp in the unpainted plaster (as a darker area) after I stripped the walpaper off. You could feel it by touching it too. Hi, What kind of wallpaper was this, normal or vinyl? Woodchip - paper. It's really hard to ascertain if a DPC is even present because the outside of the house had ben rendered with some strong mortar. Does the rendering go all the way to the ground? Yes, it does. I noticed too that the tarmac public pavement running along that wall is above the level of the bottom of an airbrick in that wall. Jake |
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On Tue, 09 Nov 2004 18:40:23 +0000, The Natural Philosopher
wrote: If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Get the boys in. Its easier. It's certainly tempting, except that I wouldn;t know if I could trust 'em to do it right... There's the old adage: "If you want to do it right do it yourself, yes"? Cheers, Jake |
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In message , Jake
writes On Tue, 09 Nov 2004 18:40:23 +0000, The Natural Philosopher wrote: If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Get the boys in. Its easier. It's certainly tempting, except that I wouldn;t know if I could trust 'em to do it right... There's the old adage: "If you want to do it right do it yourself, yes"? I did -- geoff |
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On Tue, 9 Nov 2004 04:12:14 -0000, Rob Morley
wrote: Yes, there is an issue with rainwater gathering on the pavement outside to some extent, but I can't do much about that. If any of the pavement is yours then put a drainage channel in, if it's the council's then try to get them to do it. The pavement is the council's. I'm really not sure if that's the cause of the problem though. The rain doesn't settle that badly. But I noticed that it's probably higher than it was when the house was built because it is above the level of the bottom of an airbrick (it doesn't look like a Victorian airbrick, but maybe a 1940's one. I suspect it was installed back in the 1940s to try and cure the problem which had already started way back then. I can't imagine what the council could do to improve the situation. If the cavity was empty, and deep, I would have expected the damp to stay in the outer skin of the wall. But for all I know, the cavity could be filled up with old mortar that's dropped down from above, etc. The one thing I am sure of is that the plaser used on the bottom four feet of the interior, is definitely the worst sort that could have been used. It sems to soak up damp like a sponge. Just outside the affected room, the same wall extends about 9 inches before the front door jamb. That 9" was one of the worst-affected bits. I installed a 9" x 6" terra-cotta air brick just there, and covered it with a white plastic vent-cover, so that it wouldn't stick out like a sore thumb. It certainly did go a long way to curing the problem just there, because the air brick absorbs the damp and lets it evaporate into the air that passes through the air brick. Perhaps I should employ that method all the way around the affected room, installing them every five four feet or so. I think it might work, but it's not the most aesthetic solution. I think rendering the bottom 4 ft of the interior with sand+cement mortar would also be desirable. Jake |
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Jake wrote:
On Tue, 09 Nov 2004 18:40:23 +0000, The Natural Philosopher wrote: If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Get the boys in. Its easier. It's certainly tempting, except that I wouldn;t know if I could trust 'em to do it right... There's the old adage: "If you want to do it right do it yourself, yes"? BUT you will get guarantee from them which looks good when selling. Cheers, Jake |
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On Wed, 10 Nov 2004 11:03:55 +0000, The Natural Philosopher
wrote: Jake wrote: On Tue, 09 Nov 2004 18:40:23 +0000, The Natural Philosopher wrote: If it is effective, can anyone ecommend a cost-effective place to hire the gear from and where to buy the liquid? Any tips on actual application? Get the boys in. Its easier. It's certainly tempting, except that I wouldn;t know if I could trust 'em to do it right... There's the old adage: "If you want to do it right do it yourself, yes"? BUT you will get guarantee from them which looks good when selling. Good point. Thanks for that one. Jake |
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(xavier) wrote in message . com...
(N. Thornton) wrote in message . com... and dpc injection can result in the fabric of the building beginning to disintegrate near ground level. It is not suitable for Victorian buildings. What is your proof for this statement? 1. Understand how these buildings work. 2. Go look at some. 3. Talk to some experts too. 1900 houses are built of very soft very permeable bricks. They usually have no dpc. So water is drawn up the wall through the bricks and mortar. This evaporates from the brick surface, keeping levels of damp below problematic. Now, if you add a chemical dpc, this water dissipation is considerably hampered, and the bricks below the dpc reach a much higher dampness level. When it freezes, the water expands slightly and the bricks steadily disintegrate. This can be seen on many Vic houses, bricks below injected dpcs disintegrating. Uninjected houses that have been maintained more appropriately do not suffer anything like as much from this problem. If the house is built of brick or stone then why should a silicone injection cause it to deteriorate any more than a brick or stone which is in a house built in the 30's? Depends on brick type. Vic bricks were very soft and very porous, ie very easily damaged by too much water content freezing. http://www.periodproperty.co.uk/cgi-...rum2.pl?#34641 An excellent site but there are other opinions. Obviuosly, one should consider them all and evaluate them. Some stand up better to scrutiny than others. Also, I can't see the connection between breaking off the mortar and the condition of the slate. Are you suggesting it's somehow become a structural item? I'm not being facetious,I'm genuinely puzzled. if you prise hard cement off brittle slate it tends to break. Ratbond is a cheap way to build walls quickly and, according to BS6576, is not to be injected under any circumstances. But this is because of its construction, not its content! I'm not familiar with that, why is it not to be injected? NT |
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"Jake" wrote
| .... the rendering at ground level is particularly | hard. Looks like a 4+1 mix. I wonder if it could be | removed... That sounds like an excuse for a thread about SDS drills and chisels Owain |
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(Jake) wrote in message ...
On 10 Nov 2004 09:01:12 -0800, (N. Thornton) wrote: On Tue, 09 Nov 2004 23:03:01 +0000, Pete C wrote: Does the rendering go all the way to the ground? Yes, it does. I noticed too that the tarmac public pavement running along that wall is above the level of the bottom of an airbrick in that wall. 2 causes of damp right there. You need bare brick at the wall bottom so that damp wicked up can get to evaporate away. Thats how Vic non-dpc walls control damp. That's unfortunate.... the rendering at ground level is particularly hard. Looks like a 4+1 mix. I wonder if it could be removed... Well, bear in mind youve got soft brick underneath... chisel it off and the bricks will be trashed. If you ask people on http://www.periodproperty.co.uk/cgi-...rum2.pl?#34641 some of them have successfully done it - I wouldnt dare myself though. But it is whats needed to sort the damp out. What I would dare do is locate the joints and angle grind the render off over the joins, and repoint those with lime. Lime is porous and lets moisture out, cement doesnt so well. Realise the net moisture flow is from inside the wall out, not from rain in, so porous is whats wanted on these non-dpc walls. NT |
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(Jake) wrote in message ...
On 10 Nov 2004 08:59:31 -0800, (N. Thornton) wrote: (Jake) wrote in message ... the biggest nightmae though. I just want to sell the house. I'm now if all you want to do is sell, a dehumidifier would be cheaper than buiding work. Thanks - yes, I guess a dehumidifier might be significantly better than no dehumidifier.... I can't imagine it drying the walls out very much, especially in the wet season, but I might be wrong.. Jake Water evaporation from the wall is slowed down by dampness in the air. Dry the air and evaporation will happen faster. Consider that clothes will dry overnight in a dry house, but take days in a damp house. Whether its enough on its own, who knows, only one way to see, but certainly it'll help. IIRC your walls are covered on the interior with some kind of waterproof paint or something, this wants removing really. Gypsum plaster and emulsion all considerably reduce evaporation, thus increasing damp in the wall. The standard proper fix is to remove plaster and replaster in lime. Lime is porous, and greatly improves the drying. When built, these walls would always be plastered in lime, they are not designed for gypsum plaster, and some cant work with it. Realise though that building material is very slow to dry, weeks per inch of brick. A dehumidifier would speed this up. NT |
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(Jake) wrote in message ...
On 11 Nov 2004 04:58:06 -0800, (N. Thornton) wrote: Whether its enough on its own, who knows, only one way to see, but certainly it'll help. IIRC your walls are covered on the interior with some kind of waterproof paint or something, this wants removing really. Gypsum plaster and emulsion all considerably reduce evaporation, thus increasing damp in the wall. The standard proper fix is to remove plaster and replaster in lime. Lime is porous, and greatly improves the drying. But it's very absorbent too - so that is sort of contrary to the usual advice about plastering with sand & cement mortar to block the flow of moisture to the interior wall surface, yes? Its contradictory to that popular poor advice, obviously. The idea is to dry the wall out, not trap the water in it. If you seal the 2 sides of the wall, the wall will simply head for the level of damp of the ground it sits on, which will be more wet than damp. When built, these walls would always be plastered in lime, they are not designed for gypsum plaster, and some cant work with it. Realise though that building material is very slow to dry, weeks per inch of brick. A dehumidifier would speed this up. Thanks for the suggestions. And after lime mortar is applied and dry, what sort of finishing coat would you use? And what paint would you use, if not emulsion? distemper would be the best choice. However with Vic houses you can usually still get away with emulsiion once you fix the other issues. NT |
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On 12 Nov 2004 17:42:45 -0800, (N. Thornton) wrote:
(Jake) wrote in message ... On 11 Nov 2004 04:58:06 -0800, (N. Thornton) wrote: Whether its enough on its own, who knows, only one way to see, but certainly it'll help. IIRC your walls are covered on the interior with some kind of waterproof paint or something, this wants removing really. Gypsum plaster and emulsion all considerably reduce evaporation, thus increasing damp in the wall. The standard proper fix is to remove plaster and replaster in lime. Lime is porous, and greatly improves the drying. But it's very absorbent too - so that is sort of contrary to the usual advice about plastering with sand & cement mortar to block the flow of moisture to the interior wall surface, yes? Its contradictory to that popular poor advice, obviously. The idea is to dry the wall out, not trap the water in it. If you seal the 2 sides of the wall, the wall will simply head for the level of damp of the ground it sits on, which will be more wet than damp. The plaster that's already on the walls inside, seems about as absorbent as lime plaster. There's a party wall, perpendicular to the damp side of the house which divides the lounge from the hall. In the hall, the plaster is lime plaster, but in the lounge, the plaster is some modern but similarly absorbent plaster. Both felt equally damp to the touch. I appreciate your comment about the rendering going down to the ground outside preventing evaporation. It may be difficult to emove that, but it would be easy to install absorbent air bricks, say every six feet, close to ground level. But drying out the exterior skin of the cavity wall isn't really going to cure the rising damp in the inside skin, is it? I could install some absorbent airbricks in the inside skin, below the level of the suspended floor. I'm not sue how many to install.... one every four feet or so perhaps. When the holes for the air bricks are cut, I can also clear out any debris in the cavity hopefully. A lot of air bricks will obviously detract from the thermal insulation of the cavities, but if it cures the damp, I'd be likely to go for it... Jake |
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(Jake) wrote in message ...
On 12 Nov 2004 17:42:45 -0800, (N. Thornton) wrote: The plaster that's already on the walls inside, seems about as absorbent as lime plaster. How did you judge absorbency? I'm not sure how you can. Either it'll lime or gypsum, clay plaster is most unlikely. There's a party wall, perpendicular to the damp side of the house which divides the lounge from the hall. In the hall, the plaster is lime plaster, but in the lounge, the plaster is some modern but similarly absorbent plaster. modern plaster is not similarly absorbent. Both felt equally damp to the touch. You cant judge moisture content by feel as far as I know, hence the widespread use (and misuse) of damp meters. I appreciate your comment about the rendering going down to the ground outside preventing evaporation. It may be difficult to emove that, but it would be easy to install absorbent air bricks, Air bricks arent absorbant. Removing that render is the one big effective thing to do, but really only if you can do it without damaging the very soft bricks underneath. If not, you could at least cut through it gently over the mortar joints and expose those. The remaining render will fall off one day, but will take years to loosen its hold, sometimes a lot of years. say every six feet, close to ground level. But drying out the exterior skin of the cavity wall isn't really going to cure the rising damp in the inside skin, is it? It would, if you had rising damp. Swapping the saturated cavity air for fresh would reduce the RH in the cavity air, thuse permitting evaporation from both skins. But what looks like rising damp is normally not rising damp. Rising damp is far from common, it is now realised that it has been very overdiagnosed, and often still is. I could install some absorbent airbricks in the inside skin, below the level of the suspended floor. Hang on, are you saying you have a cavity wall, timber suspended floor, and no airbricks? If so, something is wrong there. And will need putting right before the floor structure rots. People have been known to render over airbricks before! I'm not sue how many to install.... one every four feet or so perhaps. When the holes for the air bricks are cut, I can also clear out any debris in the cavity hopefully. A lot of air bricks will obviously detract from the thermal insulation of the cavities, but if it cures the damp, I'd be likely to go for it... Jake Jake, I'm going to be absolutely straight with you, you dont understand what youre doing, and need to learn. Otherwise youre thrashing about in the dark, doing work that doesnt need doing and wont wotk anyway. Its not difficult to learn, really its not. Try these guys: http://www.periodproperty.co.uk/cgi-...sing/forum2.pl they'll take you through it bit by bit, then you can apply true expertise to your house. Best of luck, NT |
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On 14 Nov 2004 16:59:44 -0800, (N. Thornton) wrote:
(Jake) wrote in message ... On 12 Nov 2004 17:42:45 -0800, (N. Thornton) wrote: The plaster that's already on the walls inside, seems about as absorbent as lime plaster. How did you judge absorbency? I'm not sure how you can. Either it'll lime or gypsum, clay plaster is most unlikely. There's a party wall, perpendicular to the damp side of the house which divides the lounge from the hall. In the hall, the plaster is lime plaster, but in the lounge, the plaster is some modern but similarly absorbent plaster. modern plaster is not similarly absorbent. Both felt equally damp to the touch. You cant judge moisture content by feel as far as I know, hence the widespread use (and misuse) of damp meters. I appreciate your comment about the rendering going down to the ground outside preventing evaporation. It may be difficult to emove that, but it would be easy to install absorbent air bricks, Air bricks arent absorbant. Removing that render is the one big effective thing to do, but really only if you can do it without damaging the very soft bricks underneath. If not, you could at least cut through it gently over the mortar joints and expose those. The remaining render will fall off one day, but will take years to loosen its hold, sometimes a lot of years. say every six feet, close to ground level. But drying out the exterior skin of the cavity wall isn't really going to cure the rising damp in the inside skin, is it? It would, if you had rising damp. Swapping the saturated cavity air for fresh would reduce the RH in the cavity air, thuse permitting evaporation from both skins. But what looks like rising damp is normally not rising damp. Rising damp is far from common, it is now realised that it has been very overdiagnosed, and often still is. I could install some absorbent airbricks in the inside skin, below the level of the suspended floor. Hang on, are you saying you have a cavity wall, timber suspended floor, and no airbricks? If so, something is wrong there. And will need putting right before the floor structure rots. People have been known to render over airbricks before! Actually, come to think of it, I did see airbricks below floor level, but didn't notice how many. I'm not sue how many to install.... one every four feet or so perhaps. When the holes for the air bricks are cut, I can also clear out any debris in the cavity hopefully. A lot of air bricks will obviously detract from the thermal insulation of the cavities, but if it cures the damp, I'd be likely to go for it... Jake Jake, I'm going to be absolutely straight with you, you dont understand what youre doing, and need to learn. That's why I'm seeking advice here. :-) Otherwise youre thrashing about in the dark, doing work that doesnt need doing and wont wotk anyway. Its not difficult to learn, really its not. Try these guys: http://www.periodproperty.co.uk/cgi-...sing/forum2.pl they'll take you through it bit by bit, then you can apply true expertise to your house. Thank you for the suggestion. I'll see what they say. Thanks for the other suggestions too. Jake |
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