I am decorating a bungalow built in the late 60's, and most rooms had some horrible vinyl floor tiles, which it seems had shrunk as there was a ~5mm gap between them. On lifting them, in some places the screed felt decidedly damp, no obvious wetness, just cold and damp. In a couple of places where the tiles had not adhered, the screed looked dry, whereas in adjacent areas where the tiles had adhered, the screed felt damp. After a day or two the damp areas have dried. I am told that vinyl tiles can 'sweat'. Could someone explain the cause of this please?

I assume that it is either condensation due to the thermally insulating tiles keeping the screed at a temperature below the dewpoint, or some damp coming up from below, and not being allowed to evaporate. I assume underlay and carpet would not lead to 'damp' due to it allowing the floor to breath more.

Oddly a handheld moisture meter set to its 'materials' setting did not show elevated damp in the floor, just 0.8% compared to typically 0.5% in plaster walls. I'm not sure if the meter can be trusted.

The house had been treated for damp 20 years ago, with a chemical damp course injected and tanking of some walls to about 1m above ground level. There is (almost) no obvious sign of damp, apart from a few small patches of mould found under the wallpaper I removed, but fairly normal I would hope. But, one piece of skirting board, probably in place since the damp proofing, if not earlier, had some apparent rot in one place. No fungus visible, but it seems to have lost some volume from the back. It did not feel rotten i.e. squashy and lacking integrity. A moisture meter reading from the bottom of the skirting was high (25%) but I had earlier spilt some water in that exact area when removing a radiator, so unfortunately the reading is unreliable. The reading at the top of the skirting was ~12% i.e. normal. (Using a cheap handheld meter.) I would have naively expected a more elevated reading if the bottom had suffered elevated dampness for long periods but I might be wrong.

Lastly, I am having new skirting board fitted, and I like the idea of MDF. Am I right to assume this would be okay if there was mild damp, which might be the case.

Oh, I nearly forgot to add that I had a home buyers report done and he did not find damp, but I'm not sure I trust these surveys unless the damp is severe.

Leif,
Warning, those tiles probably contain asbestos!

SSM

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Measure twice, cut once!

i have to have asbestos surveys done on all the council properties i am working in , 10% have very small traces of chrysotile (white asbestos) in there vinyl floor tiles . they also check the artex and the bitumen sink buffer pad ( which i had never thought about prior to this contract )

Hi Bones,
Guess who's just finished an asbestos course!!!!!!

SSM

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Measure twice, cut once!

Was boring as hell until the bloke started going on about 'crocodiles'

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Measure twice, cut once!

i was supposed to attend a refresher last week , but council agreed because they get surveys done before i go in i dont need to attend which is a shame , fancied a day off kitchen fitting with pay lol

so where u been hiding , u been missing for a while ?

Yes mate, missing in action, got made redundant from TW, misses chucked me out, moved upppp north, got new job, bought laptop, got broadband and here I am!

SSM

_________________
Measure twice, cut once!

wow m8 tough going , glad u got back on your feet relatively quick.

Anyone got an answer to my question about the tiles and sweating?



Thanks, I was warned by a poster on the tiling forum. I found out after lifting them, and they are now stored in the garage, and I will get them tested. I have nightmares where I am chased by a large vinyl tile covered with a thick layer of sticky glue. (They are a bitch to remove.)

leif , are you the same leif from the motoring forum ?

Which motoring forum? Car4Play? Honest John? If so, then yes.

yeah thats the ones , thought it was too much of a coincidence

What is your user name on those forums?

it was bones in honest john , but then when it all shook up and most left i never actually joined c4p , i just tend to read new posts every few days , i like to know rattles latest downer on life

Honest John went down hill IMO. Sadly.