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french_guy 12-26-2012 08:05 PM

Underlayment for laminate

I just bought 300 sq ft of laminate at Lowes (Allen+Roth, 10mm, AC4 with 2mm padding underneath - "Russet Oak")
I will put it in my family room to replace the carpet (concrete slab)
But I noticed the floor was "cold", and I though it could be the right time to do something to improve floor insulation
I saw at Lowes some 1/2" 4x8 extruded foam boards (green)
I was thinking about laying down that foam, plus some plywood or OSB on top of it
What do you think? Does it make sense?
How should I attached the foam on the concrete? And the wood on the foam?

epson 12-26-2012 08:37 PM

You can try using liquid nails. check out the link:

french_guy 12-26-2012 08:41 PM

Liquid nail to attach the foam to the slab or the the plywood to the foam, or both?
and other than that, what do you think about the idea?
At Lowes, they said I should call Allen+Roth to make sure it won't void the warranty
But with some OSB or Plywood over the foam, I don't see how it could be too flexible to damage the groove and tongue system !!!
By the way, what should be the thickness of the wood layer?

epson 12-26-2012 08:51 PM

You can use it on both. But they do make an adhesive for flooring to be applied on the subfloor and then applying the flooring. It is always best to call the manufacture and ask them on how you intend to apply the flooring and if it would void the warranty just to be on the safe side. Never hurts to asků check out the link:

subfloor should be 5/8''

joecaption 12-26-2012 09:32 PM

How do plan on finishing out where it meets the other floor?
Laminite need to float, so any transition stips would need to be under cut to allow them it to move.

Seattle2k 12-27-2012 01:16 AM

Lowes recommended you call Allen+Roth? Allen+Roth == Lowes.

french_guy 12-27-2012 07:09 AM


Originally Posted by joecaption (Post 1080293)
How do plan on finishing out where it meets the other floor?
Laminite need to float, so any transition stips would need to be under cut to allow them it to move.

The whole floor in the family room is "recessed" - it is 1 step below
There is no direct link with other floors
And by the way, there is no door or door wall
So the laminate will be floating, with 1/4" gap all around

french_guy 12-27-2012 07:14 AM


Originally Posted by Seattle2k (Post 1080394)
Lowes recommended you call Allen+Roth? Allen+Roth == Lowes.

Yes, that's a good point
Well, actually when I realized they didn't know about my solution I suggested I should call the manufacturer to verify the warranty and they said "yes, you should" when they should have said "No need, Allen+Roth is us and we can tell you yes or no right away"
I don't know what I'm going to do.....I would like to do it right, but it's going to require more money for that sub-floor (300 sq ft of foam and plywood)
On top of that, there will a piano in 1 spot, and that one is very heavy !!!

Bud Cline 12-27-2012 08:43 AM

DON'T DO IT!:) You are asking for trouble and wasting your money.

french_guy 12-27-2012 11:52 AM

So 6 mil vapor barrier and the laminate on top of it will be good enough in your opinion?

french_guy 12-27-2012 12:40 PM

OK, I removed the carpet and the tackstrips
1) I noticed there was a gap between the baseboard and the floor, and I could feel some cold air....I was thinking to use some spray foam to seal that gap all around. Which one should I use: the one for windows that doesn't expand too much, or the regular one?
2) When I removed the nails from the tackstrips, the concrete was cracking (size of a quarter or sometimes a little bit larger, and 3 or 4 millimeters deep)
Should I patch those with concrete repair mix?

epson 12-27-2012 03:26 PM

The reason the baseboard is above the floor is when the carpenter installed it he compensated for either carpeting or wood floors were going to be installed later. You can either remove the baseboard and lower it after you installed your laminate or install a ╝ round to cover the gap. As per the concrete cracking, yes you should fill in all the divots and make smooth as any inconsistency will show.

french_guy 12-27-2012 06:13 PM

OK,I filled up the gap with PU foam (I tried both, the one for windows and the "great stuff" - I do prefer the last one)
Will have to cut it tomorrow, patch the holes and will verify the floor is flat
I guess I will start laying down the laminate by Saturday
Since the tongue must be cut for the 1st row against the wall, I will have to buy a table saw......

french_guy 12-30-2012 07:27 PM


I am laying down the laminate
My room's length is 230.5", and plank's length is 50 3/4"
I thought I will start with a full plank, and cut the last one and start the 2nd row with what is left form that cut
But if I do that, the last piece of the 1st row would only be ~5"
So I guess I will have to cut the 1st plank to start
What should be the length of that 1st plank to minimize the waste?
Should I manage to have the 1 st and last plank of the 1st row the same length?
And how should I do for the other rows, since I will have to stagger each row by 12" (manufacturer recommendation), knowing the shortest plank should not be less than 16"....

french_guy 12-31-2012 06:59 PM

OK, I figured it out, and I don't have too much waste

One problem though: I am almost done (80%) and I have a "springy" area..:furious:
I can remove some planks to access that spot (Swiftlock system, pretty easy to disassemble), and try to put a kind of shim (thin hard material - ~1/10" thickness - the area looks like a circle, approx 2 or 3 feet diameter) between the moisture barrier and the laminate
Worst case scenario, I would have to remove the moisture barrier and put a patch of cement (with self leveling mix?)...But this would be a pain in the butt !!!!
What do you think?

Last option: I leave it as it is, finish it up, put the shoe molding and live with that "spongy" spot...hoping there won't be any damage in the long term

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