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Will plasternboard rot in a damp cellar?
The original lath and plaster ceiling in the cellar of my Victorian house is slowly disintegrating. The cellar is damp but by no means saturated. Would it be sufficient to fix up some sheets of plasterboard over the current ceiling to support it (obviously attaching to the joists) or will the plasterboard just rot?
Oh it will most certainly get damp and start to breakdown. It's only a matter of time. The question is when. Plasterboard is made up of Gypsum, which is in itself a hygroscopic material. So plasterboards suck up moisture like a sponge, as does any gypsum product (basically due to the raw gypsum being chemically processed into a hemihydrite). If you really do want a sort of quick fix (but reliable, permanent solution) then use a calcium silicate board. This will not break down. These are expensive however, and then you've got to 'finish' them within a durable damp proofing framework. So you'd almost be worth spending that little bit more and doing the job professionally and achieve the high and guaranteed standards that you'll be proud of.
Give it go. If you need any technical advice we would be happy to help.
Answered 26th Jan 2013
As long as the existing ceiling is dry then it will be ok just make sure you do not let the board touch the walls or fix a damp proof membrane along the top of the wall and ceiling edge to stop any dampness travelling across.
Answered 27th Jan 2013