[Loop]

I'm getting QuickStep 800 laminate flooring with the Unisound underlayment attached to the planks (10mm total). I'm also getting a 3mm cork underlayment. A vapor barrier will be installed too. The installation is in the kitchen/dining area and a total of ~180sq. feet. The kitchen has tiles which contain asbestos as well as the mastic and abatement is not an option (by choice + cost). The kitchen tiles are about 1 to 1.5mm thick, no more than 1/8", and the dining area is bare concrete so there is a small difference in level. Moisture does not seem to be a problem in SoCal.

Also, QuickStep has rather insistent (per their instructions) on using only QuickStep underlayments and I beleive the warranty is conditional on this clause. My reasoning is the planks already have the leveling underlayment (satisfying the warrant reqs) so a vapor barrier is all I need. The cork is for noise control and/or leveling.

Is there a problem with laying the cork first, then vapor barrier, and then laminate flooring? Is the 1/8" difference too much? Is the cork a dumb idea?

 

[Mike Costello]

I have never put 2 layers of underlayment under a laminate. I wouldnt recommend it.

The noise issue will be covered by the pad on the back of the plank.

In theory the cork sounds like a good idea for bringing your dining room up to level , but I would be concerned with it being a little too much cushion under the planks for an entire room.

Use a good quality portland cement base feather finish patch ( Plani Patch or Aredex) and feather it out as far as you can. Im talking like 6 feet or so.Then be sure to use a transition in that doorway like a T molding

 

[Don Benham]

I've used the cork underlayments under these floors before. All we did was remove the cheap foam from the back of the planks then lay over the cork. I would put the moisture barrier under the cork so there's less noise transferance.
See if the applied underl;ayment is easily removed. I would ask the manufacturer about double underlayment. Most have a website you can e-mail for specific questions.
Given the choice between Plani-Patch and Ardex I go with Ardex all the way. I may be biased but there is nothing finer for the purpose.

Best of luck
Don

 

[Loop]

Thanks for the quick response! I just emailed a question to Unilin about the double underlayment. I'll put the answer out here when I get it.

I was just reading the Pergo installation instructions and their definition of "flat" is within a 10 ft. radius there must be no more than a 3/16" difference (4.7625mm). Other maker's also say something similar.

With that said, I believe it is a good idea to feather the transition regardless of what I do. Considering the area is about 20x10ft, is there really a requirement (or recommended good practice) for a T-molding between the kitchen and dining area (dining area ~ 1/8" lower than kitchen)? I was hoping it could be seamless.

 

[Loop]

Unilin sure got the answer to me fast. Here it is:

The floor needs to be flat to within 2mm/3ft of unevenness.

It must be stable and have no moisture problems.

Yes, you can use cork under the Quick-Step.

The product you have is Quick-Step Sound. It is the 8mm planks with the padding attached. You still need a moisture barrier directly under the laminate. The vapor barrier must plastic of 6 mil thickness. We have such a moisture barrier in our line called Quick-Step Screen DPM.

Moisture barrier DIRECTLY under the laminate? That is why I wondered if the cork could be on the concrete, then the moisture barrier, then the padded laminate. I will ask for clarification from Unilin but opinions are still definitely welcome.

 

[Mike Costello]

Sounds odd to me to put the barrier over the cork but under the laminate. Like Don pointed out it could make some noise. But like I always say, when in doubt do what the manufacturor tells ya.Just keep your correspondence on record .


I agree with you about Ardex too Don. Nothing beats it.

Your well within the limit to do it without a transition. the reason I had suggested it would have been to help a bit with your hieght difference.

 

[Don Benham]

I can't think of a reason to put the barrier over the cork. I see it protecting the laminate either way but under the cork protects the cork as well. However, after clarification from Unilin, do it their way. And yes, save all coresspondances.

Don