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damp course or not

Postby stew » Wed Nov 14, 2007 5:47 pm

I have to remove all vinal tiles from the floor, the concrete underneath looks and feel dry and is quite smooth the question is do i need some sort of damp course laid.
I intend to lay parquet wood blocks to the floor, i suspect the whole ground area of the house has a damp course already in place.

the tiles i removed were stuck to the concrete.
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Postby NimbusII » Sat Nov 17, 2007 8:59 pm

Yes, allways lay some kind of DPM just to be on the safe side.
If you are going to stick you parquet to the subfloor this is basically the way.
I would expect the tiles were stuck using bitumen(black tar like).
you will need to scrape all or as much of this up as possible, then you should lay a 2 part epoxy DPM, this is mixed together and applied to you floor in to layers, rolled one way on one layer and crossways on the following layer.(make sure there are no pin prick holes at all)
Once dried the floor can then be leveled using a self leveling compound once dry prime and stick parquet leave to dry then fill and sand `n` seal.
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Postby Vix » Sun Dec 02, 2007 7:53 pm


I have a similar problem: I just took up some cork tiles in my basement bathroom which seemed to have a very thin, brittle layer of vinyl under them. then there was a layer of black bitumen-like stuff on the concrete/screed which I assumed was the original DPM, but from your answer it sounds like this could just have been the old adhesive?

So basically, i'm not sure if the floor already has a DPM or not! I took the bath panel off and had a peek around under there: it looks like there's a polythene membrane poking up around the walls, but is it safe to assume that this in place on the rest of the floor? It seems dry to the touch.

Next question: I want to lay some rubber flooring. I was going to put down a rubberised bitumen DPM first of all (if neccesary). Then can I just put a self-levelling compound straight on top? or do i need another level of screed? then can i lay the rubber flooring on top of the self levelling compound?

Really appreciate any advice - the ceiling is SERIOUSLY low already so i want as few layers as possible!

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Postby NimbusII » Fri Feb 01, 2008 7:19 am

Hi Vix,
You will need to scrape as much of the bitumen up as is possible.. more the better. Then apply a 2 part epoxy liquid membrane as instructions on tin, you can then screed/level the floor. If you do not add the epoxy dpm and just screed you will either get water between the screed and vinyl or the screed could blow...
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Postby osceli » Thu Feb 07, 2008 5:30 pm

I,ve just read the replies to your queries and do not agree. A liquid DPM should only be applied if there is rising moisture. From what you are saying I would not have thought you would have a damp problem. The easiest way to find this out is to use a surface moisture meter which will give you dampness reading insatntly. If the meter shows there is moisture present you may then need to apply a DPM. Also you do not need to remove all the old adhsive as there are latex products on the market that you can lay over adhsive residues. Be aware that wood can be very problematic if the right preparation and installation is not done properly. My advice would be to get a professional out and let them see the situation you have. Any good retailer should come out free of charge and perform the relevant tests and give you a quote for doing the works. You can even get 2 quotes for the work. After all you are not obligied to accept the quotes.
We survey and price alot of jobs knowing that we might not get them all and people are just using us for our knowledge. it is part and parcel of the industry. If you do get someone out try to get someone that has been recommended as there are alot of people that think they know what they are on about!!!!!
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