Hardwood on Concrete


Old 01-26-09, 12:48 PM
Thread Starter
Join Date: Jan 2009
Location: Ohio
Posts: 2
Hardwood on Concrete

I am planning on installing 3/8" Cherry over concrete. I was told by the clerk that I could install 3/8" plywood as an underlayment and nail the flooring rather than glueing it down. With this in mind I have 2 questions.

First, is this correct?

Second, what size nails should I then use to nail this down? from my simple calcualtion I would need a 3/4" nail/staple, are they even available?

Has anyone else done this before?

Sponsored Links
Old 01-26-09, 01:49 PM
Join Date: Aug 2000
Location: USA
Posts: 15,834
You can only install the way the sales clerk says if the manufacturer's instructions say that it is so. When buying flooring, it is important that the consumer know what the manufacturer's instructions are for the flooring product. Don't leave it up to sales clerks or installers. It is your responsibility to see that the people who install your floor do so per manufacturer's instructions. We've had too many posts here where installers failed to follow manufacturer's instructions.

Most major manufacturers have websites with installation instructions posted. There should be an instruction sheet in every box of flooring.

Did the sales clerk say anything about a vapor retarder? Did he ask if the concrete was above or below grade?

Most solid wood manufacturers will tell you that their solid wood product can not be installed below grade on concrete. Above grade requires vapor retarder. Most recommend a 3/4" plywood or OSB underlayment, even with 3/8" product.

Flooring needs to arrive at the job site prior to intallation to acclimate. Moisture test of concrete should have already been done to determine if moisture content is o.k. Vapor retarder and subfloor already installed. When flooring arrives, it should be placed in the area where it is to be installed. Installer should do moisture tests of subfloor and flooring. If installing strip floors there should be no greater than 4% difference between flooring and subflor. If installing plank, no more than 2% difference.

You will need a 1 1/4" cleat or staple if installing on plywood/OSB over concrete. Now, you see why 3/8" subfloor is inadequate.

Again, read your installation instructions. If you have questions, contact the manufacturer's customer service number. Don't put your investment in the hands of a sales clerk.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes