Underlay for first floor

m0t490

Hey.

Reading this and that but really could not find the answer.
10mm laminate going over the first floor where carpet was before. The sub floor is timber joist with wood boards on top.

Can I just use the 2mm Foam as underlay or better choice is the 5mm fibreboard?

The boards are pretty leveled. My only concern here is if I use foam underlay and would be enough breath underneath for the sub-floor.

FreeBear

I have used the 5mm wood fibre underlay, a 5mm extruded polystyrene, and the 2mm stuff.

5mm wood fibre - Easy to lay, and provides a small amount of insulation (handy for concrete floors).

5mm extruded polystyrene - Reasonably easy to lay and easy to cut. Reduces the noise of footsteps noticeably when compared to the wood fibre boards.

2mm underlay - Easy to cut and easy to tear if you catch it. Does little to absorb the noise of footsteps. A waste of money.

If/when I lay any more flooring, I'll use the 5mm polystyrene.

ThisIsWeird

Hi Mot.
Don't worry about the existing flooring not being able to breathe - it'll be fine.
Read the instructions given with your flooring. It'll probably warn against using too thick, too springy, underlay, so that's why thin stuff is often recommended. If it compresses too much, it'll put strain on the plank joints, especially if they are the 'click' type.
The fibre stuff is good - doesn't compress etc - but I don't see why it might be needed here.
Anyhoo, read the instructs, and see what it says.

m0t490

ThisIsWeird said:

Hi Mot.
Don't worry about the existing flooring not being able to breathe - it'll be fine.
Read the instructions given with your flooring. It'll probably warn against using too thick, too springy, underlay, so that's why thin stuff is often recommended. If it compresses too much, it'll put strain on the plank joints, especially if they are the 'click' type.
The fibre stuff is good - doesn't compress etc - but I don't see why it might be needed here.
Anyhoo, read the instructs, and see what it says.

Thank you.
In this case the floor is GoodHome Ledbury wide plank 10mm

"Underlay type required	2-3mm foam underlay"

Well the existing floor is not 100% levelled and has some imperfection as it wood boards so I believe there is a need of some underlay.
But, good thing it's the wide version laminate , bridge over more gap/sag

ThisIsWeird

m0t490 said:

Thank you.
In this case the floor is GoodHome Ledbury wide plank 10mm

"Underlay type required	2-3mm foam underlay"

Well the existing floor is not 100% levelled and has some imperfection as it wood boards so I believe there is a need of some underlay.
But, good thing it's the wide version laminate , bridge over more gap/sag

In which case, that's the stuff to use. You do need an underlay - it'll clack otherwise - but it clearly doesn't want to allow much movement in it.

As for 'levelling', what's important are any deviations from the floor being 'flat'. Again, that laminate floor will have guidelines on this, so have a read of the installation instructions, and it'll say what the max deviation will be - eg 3mm over 1m or so. Use a straight edge to check this.

Imperfections are ok, as long as they don't stick up!