Flooring Underlayment

   / Flooring Underlayment #1  

B7510HSD

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Hi Does anyone have any experience with underlayment over a concrete floor?? I know I need a moisture barrier but I need 1/2" underlayment to match an existing floor how do you sucure this?? And what type of underlayment would be best for this? Thanks for any help with this!
 
   / Flooring Underlayment #2  
Are you putting down carpet on top of the 1/2" underlayment, or something else?
 
   / Flooring Underlayment #3  
I saw a guy shoot Ramset nails in 1/2" plywood over a concrete floor.
 
   / Flooring Underlayment
  • Thread Starter
#5  
I will be putting down laminate over this sub floor..Thanks for the link.
 
   / Flooring Underlayment #6  
The physical property of securing two unlike materials always adds complications. With this in mind I can only speculate that you may be attempting to install 3/4" nail down hardwood over a plywood underlayment and an existing concrete slab.

(1)There are adhesives that are advertised for this application although after the finished floor has been installed there is no way to make any necessary repair that might upset the floor system if the adhesive fails or the p/w delaminates due to any number reasons without removing the finished floor, expensive.

(2) Hardened nails shot through a ramset type powder actuated gun specially designed for this is an option, possibly in addition to adhesive. Nailing pattern for plywood usually requires a pattern to secure properly.

(3) Tap Con (name brand) concrete screw fasteners. My opinion excellent holding power, then again still large number of fasteners, requires "hammer" type drill, concrete bits, driver for elect or cordless drill suited for screw head type. I prefer bosch bulldog myself.

(4) The actual fastening can be done but there are issues. Also in my opinion even with the poly down as a vapor barrier there will be a large number of fastener holes used to secure the p/w, each one putting a hole in the polly. Freshly poured concrete seems to take forever to cure therefore releasing water between the floors.

(5) I understand well about having to match floor height, but you may have other options. Depending on the math required tile of different thickness along with a hardy (name brand) backer board of 1/2" or 1/4" can be combined to match heights. I would not personally lay tile directly to a concrete floor without a backer, imo when or if the slab cracks the crack transfers to the tile.

(6) Another option would be synthetic "snap together" floating floor. Usually has to be installed with bubble type material from same brand. It has its drawbacks as well, looks, feel, different sound walking on. All I have put down has been durable but would not make this statement across the board.

It does seem life is about compromises doesn't it. Good luck hope this helps.
 
   / Flooring Underlayment #7  
I would highly recommend not drilling/driving holes in the concrete slab. The fasteners will eventually rust/rot plus if there is any hydrostatic pressure below the slab it gives water another avenue to infiltrate.
 
   / Flooring Underlayment
  • Thread Starter
#8  
I would highly recommend not drilling/driving holes in the concrete slab. The fasteners will eventually rust/rot plus if there is any hydrostatic pressure below the slab it gives water another avenue to infiltrate.
This would be a concern as this is at the coast and things do RUST! This was a monolithic pour if that matters at all...16" walls and 4" slab all in one pour..
 
   / Flooring Underlayment #9  
I live on a slab foundation in LA. We had the house re-floored recently with hardwood. (well, it was hardwood to begin with but a broken pipe changed our world a bit).

First they filled all cracks with an epoxy, then they applied a water proof paint. They then laid down 8 mil poly. Now it gets interesting. They cut 4X8 sheets of ply into 2X4 and laid it down, with a gap between each sheet. Then they laid the floor down (in your case it would be the sub floor material). Nothing was secured to the concrete. If you secure you can get squeeks.

Hope this helps, I have pix I think of the process if you need them.
 
   / Flooring Underlayment #10  
I would highly recommend not drilling/driving holes in the concrete slab. The fasteners will eventually rust/rot plus if there is any hydrostatic pressure below the slab it gives water another avenue to infiltrate.

I would suggest dri-core too. Hope the OP is sitting when he prices it out. It's expensive stuff / sqft.
 
 
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