3/4" hardwood flooring over 3/4" OSB?

BMS98

Just tore out my 2nd level subfloor, leveled out the joists in my bedroom and put down 3/4" T&G "home advantage" OSB (a clone of Advantech?). I will say, it is rock solid, quiet as could be and smooth as glass!

Then, I was reading around today and came across an article that said don't put down hardwood over OSB. Install at least 3/8" or 1/2" plywood over it first because OSB won't hold nails. Now, I have to agree, OSB seems to "blow out" if it isn't up against a solid surface when nailed. I'm probably going to do a test piece on a scrap first and see how it does.

Did I make a mistake using OSB subflooring? Anyone used it, put down hardwood floors and lived with them for a while?

Furd

I personally would never use OSB (or worse, particle board) for a floor underlayment. I've seen too many instances where it got wet and literally disintegrated. I only use exterior grade plywood. You can use A/C but B/C is good enough and might save a few dollars.

Use screws or ring-shank nails to fasten the underlayment to the sub-floor. I also like to use a 6-mil polyethylene vapor barrier between the sub-floor and the underlayment when flooring over a crawlspace.

BMS98

Thanks. I'm not worried about it getting wet. One, it is in a bedroom and I'm putting wood flooring over it with a barrier in between. Two, it is the OSB product that has the surface and edges sealed with a latex product to protect from getting wet. I left a piece outside over the weekend with some regular type 1/2" OSB and the water was beaded up on this stuff where the 1/2" was soaked.

I'm only concerned about it holding the nails used to secure the wood floor to it.

Furd

Try driving nails into scrap pieces of OSB and plywood and then pull them out. That should give you all the answers. Getting wet is only one reason why I don't recommend OSB for underlayment.

anesthes

Most hardwood floor mfg's recommend 3/4" cdx.

If you dial the pressure in properly (so you get good penetration but not too much) on the gun it will be fine. Most new constructions use OSB T+G for subflooring because it's superior to plywood. If laid down properly, OSB has great water resistance due to the resin and it is very strong simply how it's made.

-- Joe

canadaclub

Not a big fan of OSB for a subfloor. Not a fan of it for anything really but since its cheap, it can be found everywhere.

BMS98

I actually did a test sample on the OSB. Now, mind you, it is the Advantech OSB so whether it is different from regular or not, I'm not sure, but that is what I am using. There was virtually no "blow out" on the backside which I was expecting and it is holding very solidly. I'm tempted to get a setup to measure the pullout differences between the two.

woodman58

In my area of the mid-west builders use OSB as the main subfloor in new constuction. I have been installing hardwood over it for several years with no problems. It will hold nails. It is not like the old chip board that would not hold nails. Most of the OSB they use is water resistant. The seam do not swell.

canadaclub

I hear what you're saying Woodman and I suppose its a climate issue because they tried using it up here and builders got a lot of complaints about bounce and squeaks. Perhaps if they coughed up money for glue they wouldn't have had that problem. Realistically, if you set the cleats into the joists there shouldn't be an issue but the temperature and humidity variances which occur here require a more stable flooring material.

The OP doesn't say where he is from though

Ron6519

Contact the flooring manufacturer for guidance. I had concerns about installing 4 1/4" plank maple flooring over T&G OSB and the website and the Rep said it could be done. It replaced an Ash 4 1/2" plank flooring that was down for 7 years but was destroyed by a flood.
Ron

md2lgyk

I never considered Advantech to be "OSB." If it is, it is certainly superior to any other. It has a 50-year warranty against water damage.

mem

How about shorter nails? There's no advantage to the nails sticking out the other side unless you bend them all over.

BMS98

The L-cleat nails only come in one length (2" if I remember correctly). Pretty standard. They just barely poke out the bottom of the 3/4" subfloor. Maybe 1/8".

organick

if its really advantech clone, which i believe it is, it should be fine. Read the advantech site. I have seen a lot of people recommending this stuff. Its far superior to old normal osb. It even has a 300 day no sand guarantee.