How to make OSB Subfloor level for hardwood installation


Old 09-08-09, 04:43 PM
Thread Starter
Join Date: Sep 2009
Location: Oregon
Posts: 3
How to make OSB Subfloor level for hardwood installation

We are in the process of installing brazillian cherry floors in our home and are stuck at the 'making sure the subfloor is level' stage in our prep. We have taken out all staples, screwed in any screws sticking up past the surface of the floor and now the leveling begins. It appears there is a truss under the subfloor that is higher than the rest, causing more than the acceptible 3/16" variance. How do we level the floor? (Everything we've seen so far just says "make sure your floor is level" but doesn't tell you how to do that step!) Should we just sand? Or bring up the rest of the floor? Everything else appears fairly level or at least acceptibly level and it's just this truss... unfortunately it's a truss that runs the length of the house, in a high traffic area. Any and all suggestions/help would be much appreciated!!
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Old 09-08-09, 10:00 PM
Join Date: Sep 2009
Location: Texas
Posts: 3
I am in the same boat. Any help would be greatly appreciated!
Old 09-08-09, 11:04 PM
Join Date: Dec 2008
Location: St. Louis Missiouri
Posts: 16
Hardwood Floor Question

There are a couple of solutions:
3/16 is not horrible nor un common in homes depending on age.
If it really concerns you I recommend getting a 6" level. Find where floor is level to each side of bow.
Slide level to point of where floor begins to bow. This will gage area that need to be sanded and how much. Home Depot rents a good round hardwood floor sander which will make taking that down easiest.
For Installation:
Make sure you put 15 or 30lb felt paper down. Smack stapler for this
Make sure first 2-3 rows you start are square off adjoining wall. I usually surface nail starter row to insure it stays square for when you begin installation. Periodically check measurements across row off adjoining wall to make sure rows are straight.
I would rent a pneumatic floor nailer, saves your back, faster, does a much cleaner job.
Make sure joint lines are no less than 4" spaced from row to row otherwise your side joints will look almost like a continous line.
If keeping trin down you can use a quarter round to finish room.
Again though I really don't think 3/16 is worth worrying about.
Good Luck

Last edited by Shadeladie; 09-09-09 at 11:34 AM. Reason: Link removed. Advertising not allowed.
Old 09-09-09, 07:02 AM
Join Date: May 2009
Location: Dirty South, USA
Posts: 109
I would agree....sand down the high spot. Then if you need to, you can use your 15# felt to feather away from the high joist.....don't use any type of patching compound if this is a nail/staple installation. 3/16" isn't a lot over the 8-10' span recommended, but if it jumps 3/16" in only 2'-3', I would definitely fix it.
Old 09-15-09, 09:22 AM
Thread Starter
Join Date: Sep 2009
Location: Oregon
Posts: 3
Thank you very much for your help. We sanded down the high spot (it was > 3/16 over a span of about 5 feet so we were concerned) and also found that the high traffic areas are actually low spots too. So we raised those up with some tar paper. We will begin nailing down wood tonight.

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