Tanking, Dot and Dab Walls

[Whalley]

Hello, First post here..

Just bought a house about 8 weeks ago and the house has rising damp, iv knocked all the plaster off downstairs and started my tanking, Iv done it all properly and not taken any shortcuts, so far iv put on my render coat 1.5 M high and its nearly dry i know i till have my tanking slurry to apply to the wall to totally prevent the water from coming through but once i have done this and tested all my walls for for damp can i then dot and dab my walls and skim? i have spoken to a few people who said this is fine but i would like to check with a wider range of knowledge.

Thanks in advance

 

[maaaaaaaaat]

yeah,once walls are cured of damp,just board/skim as normal...matt plasterer.

 

[Whalley]

Thanks mate,

 

[roy c]

I live in an 100 year old stone built house (20" thick) it belonged to an old dear when i bought it 13 years ago. It also had a damp problem .so what I did was knock off the original plaster back to the stone work, I re-placed the joist ends that were going into the wall with treated timber and gave them a good pasting (Preservative paste) and renewed the floor boards next to the wall and cut the new ones back so they weren't touching the wall. I also checked out the air-bricks, they were there but blocked up so I cleared the debris away and made sure I had a good air-flow. I then "dubbed" the wall out and put a w/proof scratch on, and then dot and dabbed 22mm poly back plaster board on that. I ended up doing all my downstair rooms this way and have never had a problem since. I have also done and still do this method for customers and have not had a come back in 20 odd years..I believe that you can have a "Damp Problem" and keep it contained within the walls and use a method like I have described and have peace of mind....You don't actually cure it but you control it...... But don't get me wrong it can be cured... At a cost!!!!

 

[Richard C]

Roy, that's perfection

 

[roy c]

Thanks Rich It's always nice to get compliments, I appreciate that.

 

[roughcaster]

Sound advice there for others to read Roy.

Roughcaster.

 

[Whalley]

Yeah thats spot on that thanks, Iv already pulled all the floors up inc joists and replaced, also there was no heating in the house befor and like you i also had blocked air vents, iv also just cleared my cavitys from rubble so i think that was causing alot of the problem also, ill be sticking pictures on once the project is finished

 

[roughcaster]

Look forward to seeing them Whalley.

Roughcaster.

 

[RedHerring]

I have a similar situation to Roy, but in France. I've been out there most of this year but home for the winter now 'cos we still have no heating sorted out there.
An additional comment to Roy's contribution, given to me by a local in France:
If you're boarding out the ceilings first, ensure that the boards don't touch the walls (the gap will be covered by the wall boards). And similarly, ensure that the wall boards are not touching the floor, if they are solid floors, of course.

 

[jmd1994]

I live in an 100 year old stone built house (20" thick) it belonged to an old dear when i bought it 13 years ago. It also had a damp problem .so what I did was knock off the original plaster back to the stone work, I re-placed the joist ends that were going into the wall with treated timber and gave them a good pasting (Preservative paste) and renewed the floor boards next to the wall and cut the new ones back so they weren't touching the wall. I also checked out the air-bricks, they were there but blocked up so I cleared the debris away and made sure I had a good air-flow. I then "dubbed" the wall out and put a w/proof scratch on, and then dot and dabbed 22mm poly back plaster board on that. I ended up doing all my downstair rooms this way and have never had a problem since. I have also done and still do this method for customers and have not had a come back in 20 odd years..I believe that you can have a "Damp Problem" and keep it contained within the walls and use a method like I have described and have peace of mind....You don't actually cure it but you control it...... But don't get me wrong it can be cured... At a cost!!!!

Sorry to revive this old thread, but im very interested in the method you used to tackle your damp issues, using poly backed boards.

I also have similar issues in my early 1900 semi detatched home, it has cavity walls but there filled with foam insulation (previous owner) and were getting damp coming through

Ive taken all offending walls back to brick, and was thinking to s&c followed by dot & dab, but i dont want any chance of those dreaded damp dab patches coming through the boards afterwards

So if i was to copy you, which boards would i actually buy nowadays? I imagine there are boards with poly already on?

Thanks for help

 

[roy c]

Hi jmd1994 l am on holiday at the moment but will be back home tomorrow (monday) so l will try to help you out with your problem

 

[roy c]

Yes jmd the boards are 8'x4' and have polystyrene on the back of them, you can get different thickness of polystyrene attached to the boards but the boards I used finished at 22mm. I had to dub out the walls (Throw some render on to the stone walls to fill out the hollows and then a throw a roughish scratch coat on to straighten it out a bit.) I think I made the muck about 5-1 mix of sand and cement and some w/proofer in both coats because the stone work was a sand and lime mix so I didn't want my coats to be too strong so the wall could still breath a bit .When the render had dried out I dabbed the boards on to it with multi purpose adhesive(I think it was Gyproc multi purpose) I put plenty of dots of adhesive (about every 8- 9 inches) on the wall then laid some 2"x1"battens (about 6" long sticking out from the wall so the boards were off the floor) then got a good wooden straight edge to tap the boards onto the wall and get them plumbed up. When they were all up and stuck I went around and filled all the joints with the adhesive and fibre taped them. When everything had dried out I skimmed the ceiling then the walls.( When I put the ceiling boards up first I made sure that the wall boards butted up to them and double taped the joints) none of them touched the old walls so nothing could track back and glad to say all is still dry. I was introduced to this method by an architect who wanted me to do his old stone house. There wasn't any poly backed boards then so we bought 8'x4' sheets of one inch polystyrene and glued them to the back of foil-backed plaster boards with "unibond" and laid each one on top of each other to dry and put some weights on top of them. I just trimmed the edges when I fixed them to the walls. A while after we had done this they brought out poly backed boards!!!!! Hope this helps you out ....

 

[jmd1994]

thats a brilliant help roy, cheers, appreciate it, im sure that will help people in the future who are also wondering a good way to install those boards in a damp situation

As a comparison, how would you say this method compares to battening the walls with 2x1 & gyproc duplexing with insulation inbetween?

Thanks again
Jmd

 

[roy c]

The reason I used the method that I did was because I had old stone walls. But the method you put forward would still do the same thing as long as you have treated timber and dip the ends in preservative or paste them with preservative. Also I would fix the 2x1 onto some strips of DPC to stop any damp on the back of them. Maybe drill and plug the battens and fix them with brass or stainless screws!!