I live in a 1900's terrace property and the bathroom is down stairs in an extension (with flat roof) leading on from the kitchen. From what i can make out the extension is newer construction than the rest of the house which is solid wall construction.
Between the kitchen and bathroom is a small porch area, that has a upvc back door for access to the garden. There is an interior wall, between the kitchen and porch area. ( this wall is very think and probably the original wall of the end of the house.) this wall started to show damp towards the ceiling (not the very top as i have coving )reaching down to a couple of light switches - so half the upper part of the wall, the paint has bubbled and flaked off. in certain places the plaster is soft and easy to dig out, where as the rest of it still remains as normal. my answer to all of this is to just tile over the lot, as i am not sure why the wall is damp, plus re plastering is not something i can be bothered to to and tiling would look nice and compliment the kitchen? yes, a flat roof is above and so is the join of the flat roof in to this very same wall above outside. but the back door is next the wall, and together being near the bathroom, is the damp actually condensation from steam generated from the bathroom etc? i'm not sure on the cause? if it is condensation causing this, is there some sort of pre-treatment that can be applied to the surface of the wall ( consisting of 'smooth' kitchen paint, plaster and the slightly damp plaster) then once this has had a treatment of some sort of sealant/bonding i could then just tile onto ( i'm assuming there is a particular sealant/bonding out there for adding tiles to and tile glue to ) would it be a case of pushing on some watered down PVA? I can supply images. I have the tiles and want to win this little diy project!
all so to note the switch cabling does lead to out side, would this be a possible cause to why the wall is damp? this is in place for lighting out side when i get round to it? ( once the cables are out of through the wall externally the whole is not sealed but come out underneath the flat roof finishing, so not in direct exposed to rain. - not sure if this makes a difference)
sorry for the lengthy description, trying to build the picture, will provide photos if requested to help me with my answer(s).
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