Polystyrene film on hall wall

Deerd_2

I am stripping the hall just now and uncovered an odd area on the outside external wall.When I stripped the paper off there is a thin film of polystyrene sheeting over the corner, under which is an area with black blotches on it. The hall or house has never smelt of damp. Just wondered if anyone had any ideas about this?

annie-c

I had this in my late 19thc house The black bits are where you can see the original 'lathe and plaster' walls - It's quite common in older houses that when you peel off the walpaper it may come away in black chunks - it happened to me! Some of it wasn't too bad and we patched it ourselves, but other walls needed professional re-plastering. I think the polystyrene was just an old fashioned underlay for wallpaper, so as to avoid replastering (and at a time when bare painted walls were unfashionable). I found it in my living room on all walls. Not necessarily anything to do with damp. And it scraped off beautifully, unlike the 7 or more layers of paper on some walls!!!

Deerd_2

The house was built in the 1930's.I moved in 7 years ago and to be honest a lot of things were covered up.For example the 1 inch gaps between ceiling and wall in the hall.I just wondered why they had only put this film at the external corner.I thought that it might be mildew,I'm just not sure.

annie-c

Ooh, that does sound a bit suspicious then. If you are worried about damp, most damp proofers will give an inspection for free.

whitebeams

We used to have a damp spot in the hall to one side of the front door....I am sure it was the result of warm air condensing on the coldest part of the wall. I can remember the rolls of thin polystyrene you could buy in the 1970s to use under wallpaper. Other than the fumes and aid to combustion should the unfortunate happen I thought they were a good idea. I think that the previous owners have used this to try to stop condensation on this cold spot. I think injection damp proofing is an absolute con so be very wary of paying out money for something you don't need.....All the best..Whitebeams

Deerd_2

I'm having the walls skimmed by plasterer.Is there anthing I should do treat this problem area before I get them in? I won't be getting damp proofing as there is a cellar below and I don't THINK that it's damp.Just not sure.