Laying laminate on concrete floors - drying time, etc.

seamus

Right, wanted to get some level of independent opinion because we have a bit of finger pointing going on.

Got an extension, which obviously included pouring a new concrete floor for half of the kitchen, and a small section at the front door.

Got a laminate put down throughout the downstairs, it's all continuous, no separation at thresholds or anything.

Within a couple of weeks, a couple of the planks in various spots - mostly at the new floor had separated at the joins. Not pushed apart, but when you stand on it, that plank goes down (up to 10mm) while the ones around it stay in place. In some spots the floor is noticeably "bouncier" than others.

Flooring supplier, flooring manufacturer, builder, and another professional have all separately looked at it. General consensus seems to be that the wood was laid too soon after the floor was poured (probably 3-4 weeks after), and moisture is causing the laminate to buckle.

I accept this, even though the floor has come apart in some places where the concrete is not new - maybe buckles at one point, push on planks a few metres away.

The fitter (who was hired by the supplier), contends no fault. Claims he wasn't told the floor was new. He was, because I told him to his face. But the supplier is sorting that out anyway.

The supplier and manufacturer are saying the floor will need to be lifted and the concrete left bare: 1 month for every inch of poured concrete. They want to do it ASAP so that the planks can be reused.

The builder is saying that the floor can be fitted with a membrane underneath to stop the moisture coming up, and this is what the fitter should have done originally. The fitter put down a pretty standard 1-2mm foam cushion between the wood and concrete.

In short, we have young kids, so we cannot have the floor lifted and be walking around on bare concrete till the end of Spring.

Are we better off telling them to PFO and come replace the floor in April or May? Or is there a membrane they can put down so the floor can be lifted and refit inside a couple of days?

Thanks in advance...

listermint

The floor should have been let dry, You know that already. Only remedy is to let it dry though tbh. And the manufacture isnt actually that wrong with the timescales.

There is no membrane going to prevent moisture escape (and heat) from a drying concrete floor. it just has to dry out.

You would be better lifting it immediately so can reuse boards. But ultimately wont have a perfect perfect floor as alot of the boards will have already taken in the moisture and will not be able to go back to factory shape.

I guess its what you can live with regards finish of it.

Secondly , never ever put down 1-2 mm foam. If you buy a good floor then buy good underlay. its what makes the floor.

Fibreboard or thick foam with alu backing foil on it should be what is used. Its a high traffic area and deserves it so it can last.

my advice is to probably lift it and put down foam in the interim to walk on as temporary. Or thin ply boards as temporary walking surface

seamus

Cheers. I might see so. If the boards are already boned, then they're no use to anyone. It was the supplier who made the decision to not lift the floor yet, and they're shouldering the cost, so if the boards can't be reused then we may as well leave them in place for a few months and then replace the whole thing.

It wasn't a particularly expensive floor and we're loath to start pulling everything out again after moving in. At this stage we'd be happy to let them replace any bogey planks and live with the slightly spongy floor for 3-5 years. According to the fitter though you have to pull the whole floor out anyway to replace damaged boards...

listermint

Oh well if they are replacing them then let that be that , get it in writing that you have a date in a few months time.

As for replacing a few boards, he is right you have to start from the edge and work back to the bad planks so lift most of it to get to 1 board.

A drawback of the systems.

Steve

The concrete needs to dry out - end of. Trying to keep the moisture in via a membrane won't work and may result in mold.

One DIY trick is to get a glass bowl (or even a large glass) and seal it to the floor with blu tack, if you see condensation after a couple of days then the concrete is still too wet.

lgk

Steve wrote: »

One DIY trick is to get a glass bowl (or even a large glass) and seal it to the floor with blu tack, if you see condensation after a couple of days then the concrete is still too wet.

Taping down a square of clear plastic will work too, so long as the tape seals all round.

Leaving the laminate in situ will prolong the drying time.

The US NFWA guide is a really good reference for prep and installation.

e.r

Lift floor, use 1000gauge polythene
Install new floor simples

Steve

e.r wrote: »

Lift floor, use 1000gauge polythene
Install new floor simples

You forgot to add "ride off into the sunset on your horse".

The concrete needs to dry, trapping the moisture in with plastic will only postpone future problems.

e.r

Steve wrote: »

You forgot to add "ride off into the sunset on your horse".

The concrete needs to dry, trapping the moisture in with plastic will only postpone future problems.

No it doesn’t, concrete will not break down if the moisture is trapped in or will it cause any other issues, the separation layer or DPM is to protect the moisture sensitive material ie laminate floor. While the concrete is still curing.

If that was the case, every new building around the country would open without floor finishes.

Steve

e.r wrote: »

No it doesn’t, concrete will not break down if the moisture is trapped in or will it cause any other issues, the separation layer or DPM is to protect the moisture sensitive material ie laminate floor. While the concrete is still curing.

If that was the case, every new building around the country would open without floor finishes.

So why does every box of laminate or composite floor material carry an instruction to check the moisture level?

I've seen first hand the results of your 'advice' - generally years after the fact when there's no recourse

e.r

Steve wrote: »

So why does every box of laminate or composite floor material carry an instruction to check the moisture level?

I've seen first hand the results of your 'advice' - generally years after the fact when there's no recourse

The do you are dead right, and what process do the manufacturers recommend if the moisture level is above 75%?
Sit around and wait until it drys

Steve

e.r wrote: »

The do you are dead right, and what process do the manufacturers recommend if the moisture level is above 75%?
Sit around and wait until it drys

Yes, they say do not lay the floor till it's within limits.

listermint

Steve wrote: »

Yes, they say do not lay the floor till it's within limits.

Some people like pissing away other people's money.

tenbob1

Uplift, (F77 https://www.f-ball.com/en/product/stopgap-f77-waterproof-surface-membrane/ ) depending on a moisture reading, refit. Otherwise wait until the floor is dry, polythene will not work.

Edit : On a side note, fitters should be carrying out a moisture test on every floor before they install. We insist on it being a toolbox essential.

Steve

https://www.lidl.ie/en/special-offers.htm?articleId=15370

Lidl have a cheap moisture meter at the mo, no idea if it's any good but it's cheap.