Home & Garden

What kind of underlayment is this?

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  • Sep 15th, 2021 6:55 pm
[OP]
Sr. Member
Aug 7, 2005
939 posts
316 upvotes
Toronto

What kind of underlayment is this?

I'm having my basement renovated, i've already purchased luxury vinyl 6.5mm.

My contractor is bringing in his flooring guys to lay down the vinyl over the concrete slab. I requested they use DMX 1step 2.0 however his flooring guys use a different underlayment (picture attached).

What kind of underlayment is this? Is it a suitable alternative? Or should I insist using DMX 1step or even a different product?
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12 replies
Deal Addict
Jan 21, 2011
1138 posts
543 upvotes
GTA
Not the same, you are getting a cheaper product. DMX 2.0 allows for some ventilation, what they are using will probably trap moisture if any.
Deal Addict
Apr 26, 2003
2196 posts
1216 upvotes
GTA
If you're paying extra for DMX, make sure you get it. You're not getting the right stuff. This is DMX 2.0 and it costs much more than that foil/foam stuff they have.

DMX.jpg

I put it under LVP as well in my basement and I had to ensure my contractor used the right stuff, or else they would've just used some cheap alternative.

Flooring.jpg
Deal Addict
Apr 18, 2005
3448 posts
1621 upvotes
Mississauga
Any good places to buy DMX.. I have 1000+ sqft basement to cover.
Deal Addict
Nov 17, 2012
4367 posts
3709 upvotes
Toronto
What does it say in your written contract?
Deal Addict
Dec 19, 2015
2791 posts
1456 upvotes
Calgary, AB
TLSRULZ wrote: Any good places to buy DMX.. I have 1000+ sqft basement to cover.
Home Depot.

Run it perpendicular to the direction of the boards so you don't end up with with seams in the same locations.
Member
Dec 21, 2020
442 posts
374 upvotes
How old is your home. If it's fairly new (10-15 years) you should have vapor barrier under the slab already. Getting DMX will do nothing but waste money as the concrete won't have any moisture coming through it.
Deal Addict
Nov 17, 2012
4367 posts
3709 upvotes
Toronto
RCLapCar wrote: How old is your home. If it's fairly new (10-15 years) you should have vapor barrier under the slab already. Getting DMX will do nothing but waste money as the concrete won't have any moisture coming through it.
I've never seen or read up on DMX, but it sure looks like Ditra decoupling membrane. I would think it would provide a tiny bit of insulation factor between the floor and the concrete, along with allowing any errant moisture to be managed.

Moisture comes from inside the house as much or more than from outside - a vapour barrier slapped down under a poured concrete slab isn't going to eliminate all moisture that could get trapped between the vinyl planks and the slab. I'd 100% never put any flooring directly on a concrete slab regardless of the treatment under the slab.
Deal Addict
Jan 19, 2008
1521 posts
1266 upvotes
Etobicoke
RCLapCar wrote: How old is your home. If it's fairly new (10-15 years) you should have vapour barrier under the slab already. Getting DMX will do nothing but waste money as the concrete won't have any moisture coming through it.
How are you going to know the original builder put a vapour barrier...trust them?
Member
Dec 21, 2020
442 posts
374 upvotes
torontotim wrote: I've never seen or read up on DMX, but it sure looks like Ditra decoupling membrane. I would think it would provide a tiny bit of insulation factor between the floor and the concrete, along with allowing any errant moisture to be managed.

Moisture comes from inside the house as much or more than from outside - a vapour barrier slapped down under a poured concrete slab isn't going to eliminate all moisture that could get trapped between the vinyl planks and the slab. I'd 100% never put any flooring directly on a concrete slab regardless of the treatment under the slab.
DMX is meant to handle moisture coming through the slab into the conditioned space (basement). Any in air moisture will not collect under the vinyl, just like it doesn't under drywall on the walls.

Also I didn't mean not to use ANY underlayment. Just that the stuff the installer wants to use could be sufficient and cheaper than using the DMX. The foil on the cheap underlayment should handle any minor moisture under the vinyl if it gets in there.
Member
Dec 21, 2020
442 posts
374 upvotes
xxxray wrote: How are you going to know the original builder put a vapour barrier...trust them?
It's been part of the building code (in Ontario at least) since 2006. It's also part of Radon gas mitigation, also part of the building code.
Deal Addict
Apr 26, 2003
2196 posts
1216 upvotes
GTA
RCLapCar wrote: It's been part of the building code (in Ontario at least) since 2006. It's also part of Radon gas mitigation, also part of the building code.
You're assuming builders build everything to code. :) In my old place, we found out by accident that the water main coming into the house was buried inside the slab less than a centimeter from the surface of the slab. I doubt that was to code.
Deal Addict
Nov 9, 2008
1852 posts
872 upvotes
Toronto
RCLapCar wrote: DMX is meant to handle moisture coming through the slab into the conditioned space (basement). Any in air moisture will not collect under the vinyl, just like it doesn't under drywall on the walls.

Also I didn't mean not to use ANY underlayment. Just that the stuff the installer wants to use could be sufficient and cheaper than using the DMX. The foil on the cheap underlayment should handle any minor moisture under the vinyl if it gets in there.
Can confirm - I have 6mil poly beneath my slab and installed Torlys Everwood direct on slab with no underlayment between. It's been 4 years now - no issues, no smell, I've lifted a few boards during some basement cabinet installs and they're good as the day they were laid.

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