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Damp Proofing
Tanking single skin workshop - advise needed please
Hello all,
Looking for some help please.
12 months ago I had a workshop built at the end of my garden, used primarily for storage and some woodwork.
Over the winter I had terrible issues with damp. The builders constructed the workshop from medium density concrete blocks on a concrete slab with OSB with rubberised sheet. The worst 2 affected walls were built up from the inside and these 2 walls are not accessible externally. I believe this is part of the reason water seeps in through the mortar and at ground level.
Aesthetics not important, i just want a dry area.
I understand it would be best to waterproof the walls externally but as this would be complex I think tanking with KA tanking slurry or similar might be the next best option, with a fillet seal at the bottom. I'm happy to (try to) do this myself but what has given me pause is whether I'd need to render or plaster the walls afterwards, as that's not something I could do myself.
A second question please. I plan to buy knauf 100mm ECO insulation to put between the roof beams, would using 11mm OSB be ok to board up? I'm guessing Knauf plasterboard wouldn't be suitable?
Thanks in advance! Andrew
3 Answers from MyBuilder Damp Proofing Specialists
Best Answer
A slurry (Ka or similar) will certainly reduce the likelihood of moisture ingress and if you aren't unduly concerned about the cosmetics then why not wait to see what the slurry looks like? Be aware that if the problem is not ingress it might be condensation. If that is the case, the slurry will not fix your problem. Secondly, if there is no ingress then theoretically you could use any type of sheet covering for your insulated ceiling, including plasterboard. Good luck
Answered 25th Aug 2020
Plasterboard is suitable to hold up isolation. Tank the outside with waterproofer in your render. Or you could clad the outside with a membrane under the cladding. With it being single skin walls go with cladding. Pvc cladding with a breathable membrane would be best in my opinion. Unless the damp is from your roof in which case it the leak needs identifying and resolving.
Answered 25th Aug 2020
Using a Slurry based tanking system will definitely stop any water ingress if you use a decent product. I'd recommend Sovereign or Kingfisher systems.
Dont forget to grind out a a 45 degree angle where the floor and wall meet and use a fillet of barrier mortar before tanking. tank 150mm past the barrier mortar onto the concrete floor.
With it being single skin it could also be condensation in which case either insulation using thermoboard or improved ventilation will help.
Answered 27th Aug 2020
