DPM and Adhesive for solid wood floor on concrete

I currently have a 35 year old concrete floor (36 sq m) with lino tiles stuck down with a black substance I assume is bitumen. The layer of bitumen is very thin (looks like shiny black paint) and small spots of concrete show through in some spots. I am pulling up the tiles (they pop right off) and will lay down solid oak plank flooring. I would like to put the new floor down with adhesive as I don't like the feel and sound of a floating floor.

The concrete is dry (to the touch), level and sound. However, when I laid a sample of the new oak floor on the concrete and checked it after a week, it had bowed slightly which has scared the $#!/ out of me.

My plan is to use Sikabond Rapid liquid damp proof membrane first, then an adhesive like Sikabond T54 (flexible).

So the questions are:

- How risky is this? If I make the dpm too thin (or too few coats) will I end ruining the wood and having to pull it up in a month?

- Is the product/brand choice (sikabond) ok or are there better alternatives? Don't mind paying a bit more for peace of mind.

Thanks

 

You should look at using Rewmar MS Polymer asdhesive and their Rewmar RP DPM. MS Polymer adhesives are cleaner and easier to use than the Sika PU adhesives they don't contain isocyanates which carry potential health warnings. See www.rewmar.co.uk for further information

 

False claims being spread on risks of PU adhesives

 

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I know mate, that's what I like.

 

I'd always recommend Mapei's products, Mapeproof 1k turbo or ESM surface membrane, Latexplan/Ultraplan Maxi/Renovation Screed, Ultrabond P990 1k wood adhesive make sure you prime correctly also using Ecoprim T or use Uzins products PE 400 Surface membrane, NC 174 Screed, MK 95/100 adhesive. Or if replacing concrete use Uzin's NC 190 Screed, check Rh% levels with Hygrometer if below 65% Rh you'll be fine to prime with PE 360, NC 174, then fit flooring. If you need to drop the Rh below 65% use PE 400.

 

rsb123 wrote:
False claims being spread on risks of PU adhesives

There is nothing false about the fact that PU's contain isocyanates and the risks that isocyanates pose. There is legislation relating to the labelling of adhesive and sealant products containing isocyantes which was introduced in December 2010. This requires many PU products to be labelled with the risk statement "R40 Limited evidence of a carcinogenic effect." and some products must be sold with protective gloves if the product is not trade only use and could end up in the DIY market.

Remember 50 years ago smoking was safe, and I'm confirdent that the tobacco firms would prefered you to believe that was still safe, but legislation publicised the dangers! Now I'm not suggesting that using PU adhesive is akin to smoking but the legislation is there for a reason.

If there is no truth in it and it is false, why the legislation?

Why do you think many odf the largest adhesive companies are moving to silane based and isocyante free products? Just look at the latest offerings. for example take Sika with their luanch of AT80 & AT Ultimate for the wood floor market. Neither of these adhesives are PU, both are silane based. What does that tell you about the direction of the wood floor adhesives market?

 

It tells me that they are designing products for the segment of the market that is overly cautious. PU products have not been outlawed (to my knowledge). If they come to be treated like asbestos, then I start to worry. It's a known, extremely small risk, perhaps equivalent to walking across the street or getting on an plane. I know the risk, but I don't let it stop me from getting on with life.

I'm not a chemical engineer, so I only know what I read and have to trust it:
The R40 warning is apparently given to products that are classed as category 3 (the lowest): "substances where there is only evidence in animals which is of doubtful relevance to human health."

And:
"carcinogens are defined as substances and preparations which, if they are inhaled or ingested or if they penetrate the skin, may induce cancer or increase its incidence". I plan on putting the adhesive on the floor, not making a sandwich with it.

And (from the article linked above):
"During the PU manufacture [isocyanates] are converted by reaction with polyalcohols into a material with a very low isocyanate monomer content. These substances are not volatile so they are not airborne. This means that it impossible to inhale them."

 

I do love the fact there is a little bag inside a tin of Sika t54 with "do not eat" printed on it.

 

rsb123

You are right PU products have not been outlawed but that doesn't make it safe. Bear in mind that smoking is legal and was regarded as safe 50 years ago!

rsb123 quotes - "carcinogens are defined as substances and preparations which, if they are inhaled or ingested or if they penetrate the skin, may induce cancer or increase its incidence"

Well you wouldn't eat it unless you were an idiot, and you appear to be well informed enough not to be regarded as an idiot. However, the various warnings (when you look hard enough for them) include wearing masks and gloves. Presumably because there is a possiblity of inhaling and certainly becasue you will probably get in on your skin (where it will go black and probably remain for days).

rsb123 states - I'm not a chemical engineer, so I only know what I read and have to trust it:
The R40 warning is apparently given to products that are classed as category 3 (the lowest): "substances where there is only evidence in animals which is of doubtful relevance to human health."

Well we do have to trust what we read so we hope it is easily available, but it isn't. As for the reason they have no absolute proof that it causes cancer in humans is because nobody would be stupid enough to test a human to the point of causing cancer. Hence ther are no test results on humans but there is on animals!!

That the iscocyanates are "converted by reaction with polyalcohols into a material with a very low isocyanate monomer content" means that there IS isocyante low or otherwise and there is legislation covering this iscocyanate because there is enough genuine concern about it and for them to legislate for the warning labels and risk phrases.

Some comapanies do not make it easy to find out about the isocyanates in their products, try and find MSDS information. When you do find it it's not always as complete as it could/should be. One company simply says on one of their PU adhesives MSDS that the product contains isocyanates and refers you to manufacturer for further information!!! Why not simply state the facts and be done with it? They are the manufacturer for crying out loud! Even more so if we have really have nothing to concern ourselves about as you would have us believe. Perhaps it is to make finding out so awkard that the question goes into the too difficult to deal with pile and everyone carries on in blissful ignorance. You decide because whilst I think I know the answer I can't be sure.

 

When there is a floor covering bonded with a bitumen adhesive on a ground floor it is almost certainly going to be the case that the building does not contain a DPM under the concrete.

When laying wood flooring, particularly solid but to some extent engineered also, it is imperative that moisture is suppressed from the subfloor.

To do this effectively we recommend an epoxy DPM which should always be applied direct to the subfloor. The process of smoothing over bitumen and then laying a DPM is not a guaranteed system as you are not controlling the moisture that can gets into the smoothing compound (bitumen adhesives are moisture tolerant but are not moisture barriers) and we also have a weak interface at the bitumen. In effect, should the wood want to move we have weak materials further down the floor and these will be at risk

Always recommend that on these types of installation returning to the subfloor is the guaranteed method.

Lee