Smelly Laminate Floor

[NewScot]

We have an ongoing issue with an odour which we believe to be coming from our laminate floor.

The floor sits on a ground floor concrete slab. In the past, we had an issue with water ingress and the original floor (engineering board?) was removed and replaced with 10mm laminate once the problem had been resolved.

The floor was underlayed with a foam underlay which has gold foil on the bottom. However, as there was a significant difference in thickness between the original wood and the laminate, the builders also laid additional "packing" directly onto the concrete to keep the new floor level with tiled areas around it. This appears to be a brown matting which I would guess is coir or something like that - like a very old fashioned underlay.

Our suspicion is that this has maybe soaked in some moisture and is giving off the odour in the room. It's not a damp smell - more of slightly sweet smell similar to that of irises!

The plan is to lift the floor and verify our suspicions. If we are correct we then need to replace the underlay, which is the real purpose of this post - to ask for advice on underlay.

Given we are flooring over a concrete slab and need to lift the laminate 9mm or so, what would be the best approach? I am thinking of a thin moisture/vapour barrier with taped joints laid directly over the concrete with fibreboard of appropriate thickness on top. Is that the way to go or is there a better solution?

Any and all input gratefully received!!

Thanks.

 

[dazlight]

You be best putting a liquid DPM on the concrete
Like Ardex DPM1c
That will slow any rasing moisture in the slab.

 

[NewScot]

Thanks Dazlight - though there's very little (if any) rising moisture. My concern is more about the best way to lift the laminate to the required height (ie by about 10mm)

 

[Doggit]

You could use self leveling compound after applying the liquid DPM, or glue down 9mm plywood instead

 

[NewScot]

Thanks for the input Doggit

As neither you nor Dazlight have suggested my initial proposal will not work, there are 4 proposals on the table:

1) Underlay with membrane beneath fibre board
2) Liquid DPM beneath fibreboard
3) Liquid DPM beneath self levelling compound
4) Liquid DPM beneath plywood

So, does anyone have a view on which is the best approach taking into account things such as:

a) how easy it is to do on a DIY basis
b) cost
c) effectiveness
d) long term solution

 

[dazlight]

Get a pro in id say but if not-

Test concrete for moisture if moisture found DPM to concrete
Then prime and screed to desired level.
Then laminate underlay like Timbertech 2 silver or timbermax 3
Then laminate

You shouldn't use 2 underlays under laminate

 

[Doggit]

From a DIY point of view, option 2 is the easiest. Option 1 seems to be what you already have, so ignore that one. 3 is a good choice, but it depends on your skill to get the self leveling compound level, as it never levels itself as much as it's supposed to (I know I'll get corrected on this point though) and option 4 is the best one, but are you confident about using a notched trowel to glue down the plywood - as well as cutting it square and neat so you're not filling loads or gaps.