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
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dave1949
Super Star Member
Are you putting down carpet on top of the 1/2" underlayment, or something else?
JimRB
Veteran Member
I saw a guy shoot Ramset nails in 1/2" plywood over a concrete floor.
ericher69
Veteran Member
http://www.dricore.com/en/eIndex.aspx
Floats and does not need to be secured.
Will not work with hardwood but carpet and laminate
Floats and does not need to be secured.
Will not work with hardwood but carpet and laminate
hardtime
Member
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.
(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.
ericher69
Veteran Member
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.
OP
B7510HSD
Veteran Member
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..
woodlandfarms
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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.
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.
Scooby074
Super Member
I would suggest dri-core too. Hope the OP is sitting when he prices it out. It's expensive stuff / sqft.
Dr Dave
Platinum Member
Menards and Home Depot have roles of a dimpled plastic product that you lay down first, plywood on top, it is not secured. It works like the drylock panels, but cheaper.
Dave
Dave
Milo
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Rather than go to all the expense of raising the floor I would just install a vapor barrier then lay down one of the premium (thicker) sound deadening, insulating, underlayments and choose one of the thicker, maybe 8mm+ laminates. Then make whatever kind of transition pieces necessary for where the laminate terminates or meets another surface.
KennyG
Super Member
I've used dri-core and it's great, but the OP said he only wanted 1/2". Isn't all the dri-core thicker than that? I would test the floor for dampness by taping down plastic for a day or two and seeing if it's significantly wet. If not, I would just put down a layer of cushioning underlayment and let the laminate float on that.
Tractor Seabee
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I just did a whole basement (1200SF) with laminate. It was very uneven, lots of cracks, and in a moist subgrade area. Checked all levels and determined high spots. Highest point became the reerence level. Prep: Used a cup shaped carbide concrete grinder in a 6" anglehead grinder to remove all paint and previous tile cement, gouged out all the cracks with a diamond saw blade in power hand saw, filled with epoxy patch,and put a layer of drywall fiberglass tape over all cracks embedded in epoxy. Finish: Went to a contractor specialty supply (the big box stores do not have the big sacks) and bought a pallet full of high grade self leveling underlayment. Installed a piece of ripped lumber (thickness based on reference level) at each door (5)and Rolled down a coat of masonry latex bonding agent. Mixed underlayment per instructions (water is critical measurement) and poured in place one room at a time. A small bull fload works well to consolidate and spread around. After curing of underlayment rolled down a heavy coat of asphalt waterproofing emulsion, put down a 15# asphalt roof felt in the emulsion and put two coats on top. After that cured I layed the floating laminate floor on top. Turned out beutiful. total material including laminate was less than $1.5K. Costco was closing out laminate at 50% off which helped on the cost.
Depending on your conditions; some of the above steps can be bypassed. I had the worse of all conditions to mess with.
I would not hire out to do this for someone else for less than $3K labor cost.
Ron
OP
B7510HSD
Veteran Member
Wow sounds like alot of work!! This is new concrete it was an add on 22'x10' to the existing older house...and it is above grade so other than the moisture in the concrete it shouldn't have a water problem..
Tractor Seabee
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It was a lot of work. For the underlayment go to Addison Supply in Tacoma. They are great and will help you with the details. I have been using them for 10 years.
Get the latex bonder at Loews as it is cheaper and comes in gallons.
Ron
smilindave
Bronze Member
if your floor is fairly level, just use some 1/2" hardy backer? 100% water proof and it lays flat. Lowes and Home Depot usually carry it. Since you are using laminate flooring, no need to cement or fasten in place
clemsonfor
Super Member
I would never use Laminate. I know 2 people with it. One is super cheap stuff. Its chipped at edges and is "blown up" where water sat on it unnoticed and then the "sticker" for the fake wood wore off. The other couple has what they call cheap laminate. To me its not really that cheap, was something like $3-4 sqft. It was real wood veneer adheared to like 3/8 ply. The finish is worn off in high traffic areas after like 3 years or so.
Now i dont deny that some of the stuff looks good and will last, but the good stuff costs more than real hardwood??
I laid solid 3/4" hardwood 3.5" wide planks in my home in a room that i redid the floor in. If memory serves me right i paid i think Around $3.50sq/ft give or take $0.20? Yes i had to finish it but thats really not that hard if you can stay off of it for a week or so.
Now i dont deny that some of the stuff looks good and will last, but the good stuff costs more than real hardwood??
I laid solid 3/4" hardwood 3.5" wide planks in my home in a room that i redid the floor in. If memory serves me right i paid i think Around $3.50sq/ft give or take $0.20? Yes i had to finish it but thats really not that hard if you can stay off of it for a week or so.
radioman
Super Member
I saw a show where holmes for homes took blue foam board and used that to insulate the concrete basement floor and installed 3/4 plywood on top. He used tapcon screws to hold all this down. This is obviously much thicker then OP needs, but it gives you the idea that tapcons should be ok. If you dont have water issues, and once the floor is in, you really dont need to worry about rust of screws - it probably will last 20 years or more and still hold.
