HELP "flattening" subfloor for laminate install


Old 07-09-09, 10:43 AM
Thread Starter
Join Date: Jul 2009
Posts: 5
Received 0 Votes on 0 Posts
HELP "flattening" subfloor for laminate install

Greetings and thanks in advance for all help!!!

I am rehabbing our kitchen, cabinets have arrived, and I need to level, more accurately "flatten" the sub-floor. Our home is 125 years old, the current kitchen floor is 6" wide oak tongue and groove planks, with no subfloor, so theoak T&G is the subfloor. It was a 15' span and I originally was considering tile so I installed a beam in the basement to halve the span, and I screwed the planks down, every 16" at each floor joist. Since that time we have switched to laminate "hardwood", i.e. a floating floor. So currently the "subfloor" is tight and stiff. Although I tried to lift the sagging joists as much as possible when installing the beam, there is still a maximum 1/2" valley in places. After leveling I was planning to screw down 1/4" plywood to provide a uniform surface.

So the question is how to flatten this prior to installation? I was recommended to use planipatch and screed fill the valleys. I called the manufacturer and they recommended against because the product isn't recommended for plank flooring, only plywood. He was concerned about mechanical movement of the planks with heat and moisture contraction and expansion. I'm sure I didn't eliminate it, but I did tighten the floor a lot. Sometimes it's hard to tell whether manufacturers are being ultra conservative? So I am still tempted to use some type of patching leveler...

Others have told me to layer tar paper but 1/2" seems like a lot of tar paper? Others have said plywood scraps. I wanted to avoid self leveling compounds because the old planks have a lot of gaps from shrinkage over the years and the material will seep into the basement, plus I really only want to fill the valleys, not raise the whole floor.

I have also installed hydronic radiant under this subfloor (in the joist bays underneath). I would prefer to say away from anything that will limit heat conductivity.

Maybe I am taking a risk and maybe I'm crazy, but it seems a pour and screed approach is the easiest, but this is my first floor and I am needing advice from someone more experienced than I.

again, thanks!!!
Sponsored Links
Old 07-09-09, 11:04 AM
Join Date: May 2009
Location: Dirty South, USA
Posts: 109
Received 0 Votes on 0 Posts
This is a floating installation, correct? So, lay your plywood first, then pour your leveler...the underlayment and floor are perfectly fine to install over the leveler.

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
Ask a Question
Question Title:
Your question will be posted in: