I have a property with solid stone walls. It was built in the 1920s. The damp is coming up through the solid floors and through the walls. My solution is to take up the floors and replace with wooden floors using 100mm celotex under. The new joists will be on new concrete walls not touching the outside wall. I will then put air bricks in the walls to create air flow. I will use battens on the walls with 25mm celotex and vapour check plasterboard, creating air gaps behind the board from the ground floor into the loft. The outside will then be painted with a water based paint. My intention is to create an inner envelope of celotex and fibreglass but allow the air to ciculate under the floors and behind the plasterboard. Can anyone tell me a flaw in this method. Thanks
Damp proofing solid walls
- Thread starter chucka
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the walls have penetrating wet from all sides top to bottom. I want to allow the walls to breath. By painting the outside I am stopping the water from going into the walls but what is in there needs to go somewhere. It will take many years for the walls to dry out. They need air flow to do this. The internal walls will rendered on the ground floor and where the solid walls on the first floor meet the outer walls.
sounds like you've got a good solution for the floor but i think me personally i'd be going for a breathable plaster system for the walls so that you don't have to worry about where you're pushing the moisture that you're trapping in with celotex or tanking.
lime render with a lime finish will do the job or if you want to add insulation you could use either diathonite which has a cork content or something from NBT (natural building technologies)
lime render with a lime finish will do the job or if you want to add insulation you could use either diathonite which has a cork content or something from NBT (natural building technologies)
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Thanks. I intend to remove the floorboards from the first floor and use them on the ground floor polished up, beautiful 1920s tiling at moment but oh so cold and damp. I would like to use more celotex over walls, the house is old and cold. I will look at the product you mentioned. Good idea with lime mortar, used it many times when patching walls in churches and pointing flints.
depends HOW damp it is in there i think, if it's like a basement then yes, block the water out but if it's normal solid wall construction levels and the rooms are heated inside the damp won't be an issue.
Sounds like the floors are the big issue here though?
Sounds like the floors are the big issue here though?
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Of course it's an issue, if you fill the room with damp air you get all sorts of lung ailments from airborne spores. You want a DRY house - not a wet one that evaporates into the atmosphere that you breath. Stop living in the fifteenth century - it's not clever. The 'Good life' was a TV show.
I understand your concerns Joe and this problem needs careful consideration for very important reasons, i agree.
i'm just going on what i've learnt from people like NBT who have spent years and thousands on looking at the science of this and have BBE certification for their systems which are especially for the refurb of properties like this.
if structures are kept too wet and they can't breathe and release moisture from time to time it can cause the degradation of the building fabric, another important consideration too i feel.
If you were to stop a cobb wall structue from breathing properly and for example it would quickly deteriorate, the structure of the wall and building should always be taken into consideration and treated correctly, you can't just tank and waterproof everything.
The other consideration with solid walls is that if you have structural timbers in them, like lintels etc and you're keeping that moisture in there, they can rot.
i'm just going on what i've learnt from people like NBT who have spent years and thousands on looking at the science of this and have BBE certification for their systems which are especially for the refurb of properties like this.
if structures are kept too wet and they can't breathe and release moisture from time to time it can cause the degradation of the building fabric, another important consideration too i feel.
If you were to stop a cobb wall structue from breathing properly and for example it would quickly deteriorate, the structure of the wall and building should always be taken into consideration and treated correctly, you can't just tank and waterproof everything.
The other consideration with solid walls is that if you have structural timbers in them, like lintels etc and you're keeping that moisture in there, they can rot.
Thank you for your comments. The walls on this property are very wide,solid and wet through 90 yrs of water penetration, I worked with a plasterer for many years and we did lots of damp prooofing and tanking. damp proofing was only ever used with injection and then 1mtr waterproof render. we only tanked in cellars and where the wall had earth piled on the outside like a bank or simular. The chap I worked for was of the old school where ventilation is the king, not sealing in the wet. the walls will not be able to breath from the outside because the property is in pembrookshire (lots of rain) My idea is to create air flow from the ground floor behind the new walls up into the roof space. New roof going on with a breather felt. I am also trying to insulate every wall and floor internaly as the property is big and will only have electric heating and log fires.
H
huddsspread
If it was my house this is what i would do. First im not an expert on lime so cant make comments on it
I am doing a similar job in a house built in 1890 out of stone.
I will be building a stud wall about an inch off the walls ( box in a room ) and insulating with kingspan and then vapourbarried plasterboard. The inch or so gap will be the breathing part and i also intend to make an inch gap in the ceiling in the same gap behind the new wall so the air in the roof goes down behind the new wall. Ceiling is being boarded and skimmed too. I shall be placing a few small vents in the new plasterboard wall just above the skirting.
The idea is that the loft has air circulating and this goes down behind the new wall and lets the old wall do what ever it wants. So even if the penetrating damp comes through the stone, it isnt going to affect the new walls, and the air from the loft can and will dry out the stone if it gets wet. Although the room is going to lose 3 or 4 inches around, it will be warm and dry, and no damp issues.
This maybe a good idea for you.
As for lime or new plaster etc. You could tank everything and render, then use multi finish, but you may get problems later, not saying you will, but you could. If you use lime it will breathe, but thats a whole can of worms. I havnt got any evidence that says tanking a house and then using british gypsum products will fail, but ithers have.
Go with my solution above, it may cost an extra £100 in wood but it will be right.
I am doing a similar job in a house built in 1890 out of stone.
I will be building a stud wall about an inch off the walls ( box in a room ) and insulating with kingspan and then vapourbarried plasterboard. The inch or so gap will be the breathing part and i also intend to make an inch gap in the ceiling in the same gap behind the new wall so the air in the roof goes down behind the new wall. Ceiling is being boarded and skimmed too. I shall be placing a few small vents in the new plasterboard wall just above the skirting.
The idea is that the loft has air circulating and this goes down behind the new wall and lets the old wall do what ever it wants. So even if the penetrating damp comes through the stone, it isnt going to affect the new walls, and the air from the loft can and will dry out the stone if it gets wet. Although the room is going to lose 3 or 4 inches around, it will be warm and dry, and no damp issues.
This maybe a good idea for you.
As for lime or new plaster etc. You could tank everything and render, then use multi finish, but you may get problems later, not saying you will, but you could. If you use lime it will breathe, but thats a whole can of worms. I havnt got any evidence that says tanking a house and then using british gypsum products will fail, but ithers have.
Go with my solution above, it may cost an extra £100 in wood but it will be right.
1. Lifting the solid floors might create lateral pressure depending on the foundation depth. Unless the original floors were suspended.
It would be cheaper and more convenient to buy-in a ground floor, wood floor rather than doing what you propose - that's if you go the lift and shift route.
2. What are"concrete walls"? You might be blocking sub-floor air circulation with solid walls.
3. Basement tankings often have a perimeter drain ( aka French drain ) to collect moisture that penetrates or condensates, and runs down the face of the wall. How wet are your walls?
4. Wykamol have a studded membrane that is plugged to the wall, and typically tied-in with any floor DPM.
5. Next the stand-off stud wall is built and finished ...as reqd.
6. All this studding out will create much detail work.
7. I would suggest: do not paint anything on your exterior masonry. You will be painting yourself into a corner of future troubles.
8. Air flow from open vented sub-area to loft ( is the loft ventilated? ) will strip quite a few btu's of heat. Is this a bungalow?
9. The simplest, most cost effective possible solution would be as above suggested, pour a new floor and render the interior with a sand & lime mix.
You could still have an insulated underlay and wood floor over the concrete.
10. With the above, you would get 20 - 25 years moisture free walls before the penetration began to show again.
!!. In general: hot air rises, moist air does not disappear, it has to be vented out. Venting out can be an expensive proposition. Loft condensation over the last say 25 years, has grown significantly.
It would be cheaper and more convenient to buy-in a ground floor, wood floor rather than doing what you propose - that's if you go the lift and shift route.
2. What are"concrete walls"? You might be blocking sub-floor air circulation with solid walls.
3. Basement tankings often have a perimeter drain ( aka French drain ) to collect moisture that penetrates or condensates, and runs down the face of the wall. How wet are your walls?
4. Wykamol have a studded membrane that is plugged to the wall, and typically tied-in with any floor DPM.
5. Next the stand-off stud wall is built and finished ...as reqd.
6. All this studding out will create much detail work.
7. I would suggest: do not paint anything on your exterior masonry. You will be painting yourself into a corner of future troubles.
8. Air flow from open vented sub-area to loft ( is the loft ventilated? ) will strip quite a few btu's of heat. Is this a bungalow?
9. The simplest, most cost effective possible solution would be as above suggested, pour a new floor and render the interior with a sand & lime mix.
You could still have an insulated underlay and wood floor over the concrete.
10. With the above, you would get 20 - 25 years moisture free walls before the penetration began to show again.
!!. In general: hot air rises, moist air does not disappear, it has to be vented out. Venting out can be an expensive proposition. Loft condensation over the last say 25 years, has grown significantly.
There's substantial evidence out there ref the unsuitability of using other than a lime in the mix render, and typically, a remedial finish such as limelite for damp situations.
Any expert witness in a "damp" dispute will instantly ask what the mix was. Anything other than a remedial mix and it's case over.
FWIW: i've seen browning and bonding etc. fail many times over the years.
And i've seen remedial mixes stand the test of time with and without an injected DPC.
Any expert witness in a "damp" dispute will instantly ask what the mix was. Anything other than a remedial mix and it's case over.
FWIW: i've seen browning and bonding etc. fail many times over the years.
And i've seen remedial mixes stand the test of time with and without an injected DPC.
P
Primer
You have no clue what you are talking about and giving out bad advice that will end up costing many thousands in the long run.
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