Flooring underlay on top of concrete subfloor

[mike2016]

Hi,

I've finally gotten the old carpet removed from the living room floor. Walls & ceiling painted and am putting down laminate flooring shortly (skirting to be removed first!). I'm looking at the old carpet underlay and wondering if I should leave it in place or do any prep work on the concrete slab if I remove it? I am considering putting the laminate underlay directly on top of the carpet underlay for extra insulation but is this appropriate? 

 

I did laminate on an upstairs bedroom recently and put the underlay on top of the bare floor but this is ground floor concrete so want to ensure I'm taking appropriate measures before covering it up. 

 

Thanks!

 

Edited December 5, 2017 by mike2016

[Oz07]

Probably a bit too spongy, too much stress on joints i'd of thought. Remove and fit underlay designed for floating timber floors.

[Oz07]

dpm underneath also

[Ferdinand]

Can you add 25mm or even 12.5mm of Celotex into the build up ?

 

Even that would help a lot.

 

 

Edited December 5, 2017 by Ferdinand

[Oz07]

37 minutes ago, Ferdinand said:

Can 25mm or even 12.5mm of Celotex into the build up ?

 

Even that would help a lot.

 

 

Would it really though in this "real life" scenario? How much heat is lost thru the floor of just this room in the house? I'd guess the payback time would be immense at 25mm let alone 12.5

[Ferdinand]

1 hour ago, Oz07 said:

Would it really though in this "real life" scenario? How much heat is lost thru the floor of just this room in the house? I'd guess the payback time would be immense at 25mm let alone 12.5

 

I think there may be someone here with the correct answer to that in their head already.

 

it is always the first bit of insulation that saves the most and is the most cost-effective (subject to overheads etc eg if you have to trim doors), and since you are already lifting the carpet etc it is just the extra cost of materials plus adjustments.

 

F

Edited December 5, 2017 by Ferdinand

[ADLIan]

Use correct underlay for laminate floor. Celotex, or similar, is not suitable for use directly under laminate flooring.

[Nickfromwales]

10 hours ago, ADLIan said:

Use correct underlay for laminate floor. Celotex, or similar, is not suitable for use directly under laminate flooring.

You can use much thicker engineered flooring directiy over it, but it has to form a solid deck eg minimum of 18mm. 

Its about point pressure, and laminate relies on a solid subfloor as it needs to be fully supported. 

[ADLIan]

Not sure about that Nick.

 

See instructions/recommendations from both flooring and insulation manufacturers. Problem is lots of relatively narrow planks rather than large area of flooring grade chipboard.

[mike2016]

Thanks Folks,

 

You're right about the support, hadn't thought of that. 11mm laminate would flex too much and I don't want to shell out more for bamboo or solid flooring as I'm selling in 2 years to fund the self build. I'll get standard underlay so and ask about the dpm to lay underneath that also. Thanks everyone, off to the builders providers I go!!! Plus 1 more thing for the skip today! 

[Nickfromwales]

4 hours ago, ADLIan said:

Not sure about that Nick.

 

See instructions/recommendations from both flooring and insulation manufacturers. Problem is lots of relatively narrow planks rather than large area of flooring grade chipboard.

In conjunction with a thin ply I should have added. . 

18mm plank with a proper tongue and groove is pretty robust. The laminates have nearly half the joint thickness removed so are terrible in comparison.