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OSB for Hardwood Flooring

01/06/2008 6:11 PM

I have someone putting in a hickory pecan hardwood floor in my house. The subfloor found under the carpet is 1/2" particle board over plywood. He was going to glue and nail the flooring to the existing particle board and plywood. Since I want this to be done properly and that would void any warranty on the floor, he now says that they will put 1/4" OSB or plywood over the particle board and nail down through the OSB and particle board to the plywood at the bottom. Can someone give me some clue as to what should be done here? I live in Seattle, WA, the mold and moisture capital of the world, if that makes any difference. Any help would be appreciated. Randi

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#1

Re: OSB for Hardwood Flooring

01/06/2008 7:13 PM

The answer is pretty straight forward. Think of this: WWJD. In other words, What Would Jesus DO? After all he was a carpenter.

Now, WWID? That is, What Would I Do? I would call the 1-800 number on the flooring and ask them what I have to do to not void the warranty.

Jesus would probably do the same.

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#2
In reply to #1

Re: OSB for Hardwood Flooring

01/07/2008 3:47 AM

I guess my question should have been..."should they tear out the particle board and lay 3/4" OSB instead or will this work if they just lay 1/4 OSB on top of the particle board nailing all the way down into the plywood below". Thanks for the info...I wish these people I am dealing with knew Jesus. R.

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#3

Re: OSB for Hardwood Flooring

01/07/2008 6:27 AM

Having recently laid 3/4in microbevelled tongue-and-groove French Oak flooring over the top of 3/4in flooring grade chipboard using adhesive supplied with the flooring, all that can be said is that 'there are many ways to skin a cat' (no offence, Del).

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#11
In reply to #3

Re: OSB for Hardwood Flooring

01/08/2008 10:03 AM

I hope Del doesn't take offence. The "cat" referred to in this phrase is a catfish, which is skinned since it has no scales. I know of three different ways to skin a catfish. I'm sure there are many more.

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#4

Re: OSB for Hardwood Flooring

01/07/2008 1:08 PM

I would not lay it on top of some thing as thin as 1/4 OSB. Would go to some thing thicker. Would want a good flat surface to lay it on. If it isn't flat I don't think 1/4 OSB would correct the flaws.

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#5

Re: OSB for Hardwood Flooring

01/07/2008 11:05 PM

I'm not familiar with Pecan hardwood, but have worked with Oak. If I interpret your question correctly, you have two concerns; one is about how the floor will stand up if glued and nailed to particle board or the 1/4 OSB if installed. Second is the possibility of a mould or mildew issue. I would suggest a third concern and that is matching the height of other flooring in the house(unless you are installing Pecan Hardwood on every inch of one level of your house). If there is a significant mismatch in height, this alone may make taking the pariticle board out worth it.

I personally removed my particle board subfloor because particle board does not hold flooring nails (most likely staples) worth a darn and trying to use longer ones to go through into the plywood floor underneath is a royal pain in the posterior and the floor will most likely wind up squeaking as the nails work loose over the years.

I would phone the 800 number that the company supplies with its products to double check, but for the best results, including matching the floor height of other flooring on the same level, I would go to the trouble of getting rid of the particle board.

If height matching is not an issue, I would still replace the paritcle board with plywood because the glues and resins used in plywood tend to be mould an mildew resistant and if you ever do have a major spill on the floor, plywood doesn't disintegrate like particle board does once it has been wet.

Basically, unelss the manufacturer specifically says not to, I would remove all the particle board subfloor and install the thickness of plywood necessary to match other floor heights in the home or to keep counter heights correct, if required. Remember you can put the hardwood driectly on the plywood floor if necessary. I did this with my Oak floor and the height match with the tile floor was great.

writer

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#6

Re: OSB for Hardwood Flooring

01/08/2008 12:09 AM

3/8"+ Birch plywood, as underlayment. You can overlay the chipboard, or remove it(more work) it all depends on the other floor heights, trimming problems the extra height may create....The main problem with todays flooring, is its thinness, which allows it to move around, possibly allowing moisture and water into the subfloor. B.C.,Master Carp.....

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#7

Re: OSB for Hardwood Flooring

01/08/2008 5:17 AM

I would have to confirm using plywood, the thicker the better. I have maple hardwood on 3/4" OSB, and it squeaks all over. Get rid of the particle board, no OSB. Also, make sure your plywood (both old and new) is SCREWED (even glued, as well, if possible, PL Premium) to the joists and/or layer underneath it. Stagger the plywood sheets, and glue the tongue and groove edges.

Before installing the flooring, chalk line the centerline of the joists, and insist that the installer hits EVERY joist through the plywood, as well as in between. However, with a combined plywood thickness of 1 1/2", properly anchored and secured to the joists as well as between layers, this is less than critical, but still a good idea.

You will never regret the extra effort and expense. Not only will it not squeak, you will really appreciate the solid, quality feel underfoot when walking on it, virtually forever.

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#8

Re: OSB for Hardwood Flooring

01/08/2008 8:08 AM

I install wood in Canada and I can tell you that I will walk off a job if it has OSB or partical board. Nails will not hold and moisture will be come an issue. Even if you are gluing and nailing you have to consider the integrity of the subfloor.

I know that here in Ontario the builders association has managed to manipulate some wood manufacturers to allow these sub standard surfaces to be used, but I will NOT go over these surfaces because of the problems that come about.

There is usually an instruction sheet in or on the box and it will tell you what is prefered for warranty but do yourself a favour and rip out & replace with real wood subfloor. This will give you a proper job that will last many years.

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#9

Re: OSB for Hardwood Flooring

01/08/2008 8:23 AM

You neglected to state the age of your home, but based on the presence of the particle board I'm guessing it's not a new home? If the home is several years old and in your location there's a good chance the particle board has already swollen to some degree and its nail holding properties may not be optimal already. Several years ago I pulled up carpet and put down hardwood (oak) flooring over particle board and plywood - much as you found. I would not do that again. I'm in Arkansas - high summertime humidity. While the particle board does not fail to hold nails, it does "move" - mostly swells, and in doing so has allowed the outside edges of my hardwood to raise over time. It's a small elevation, but its there and very obvious when small wheeled items such as a vacuum cleaner run over it. A second reason to not nail into the particle board is its tendency to swell if/when it literally gets wet. Any kind of "accident" which wets the particle board will swell it and it will not return to its original thickness, leaving a void between the swollen and unswollen parts which allow the hardwood to move (i.e. squeak). My suggestion, get rid of the particle board. Putting OSB back down in the place of particle board is an iffy proposition; IF you get the type that is high resin and guaranteed to not swell when wet, it might be OK but a good exterior grade plywood would seem to provide a better approach. And, don't forget the roofing felt between layers of wood, to minimize wood on wood squeaks.

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#10

Re: OSB for Hardwood Flooring

01/08/2008 9:12 AM

I'm really surprised nobody mentioned moisture content of the wood. Buy your self a moisture meter and verify the wood has less than 8 % moisture content. Even if it is kiln dried, moisture (especially in Seattle) can be re-absorbed quickly. Your floor will crack and shrink when conditions in the house are dry, over time. I also would not have a problem with multiple layers of sub-flooring if it was pre-nailed every 4-6 inches.

Good Speed !

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#12

Re: OSB for Hardwood Flooring

01/08/2008 10:08 AM

As in reply #9--be sure to put roofing felt under the new flooring. This prevents the finish floor from rubbing on the underfloor (Squeak!, Squeak!).

It only takes a few minutes extra and a few dollars worth of felt, and is cheap at twice the price.

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#13

Re: OSB for Hardwood Flooring

01/08/2008 12:58 PM

I had a similar problem in my home. I wanted to replace carpet in the hallway with 3/4" Oak and the subfloor was 1/2" plywood (bottom layer) with 3/4" particle board (between plywood and carpet padding). The installers ripped out the 3/4" particle board and put 1/2" plywood on top of the 1/2" plywood already there. We went with the two layers of 1/2" plywood because it brought the surface of the hardwood to the right height to match the carpet in the bedrooms and was thicker than the minimum thickness of 3/4" plywood underlayment. NO GLUE was used (and no regrets). We have been very pleased with the floor over the 2 years since it was installed. We plan to do the same in our bedroom.

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#14

Re: OSB for Hardwood Flooring

01/08/2008 1:01 PM

A lot depends on what is underneath the subfloor--what kind of insulation and vapor barrier to keep moisture from moving in/out of the dwelling. If there is not a good moisture barrier, the moisture content of all the flooring will change with the seasons. Also, one must open the new flooring up to room humidity and temp conditions for several (3 min) days to equalize the moisture content to avoid shrinking/swelling of the new flooring, which causes cracks and squeaking.

The key to a stable floor is a stable moisture content. assuming there is enough structural support.

Some hardwood floors are installed over 'sleepers' (2x4's,2' long) arranged somewhat randomly and staggered so the 3/4" thick flooring is supported very 12-18" lengthwise. Some installations go as far as 4'--to deliberately provide some spring (dance floors).

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#15

Re: OSB for Hardwood Flooring

01/08/2008 7:53 PM

First: I'm not a carpenter. But I recently sold my home of 10 years here in SE Florida. We to have high humidity, mold and mildew problems but not in my home. The house was built in 1953. It has a suspended, red oak floor. The strips are 1/2" x 2 and 1/2" in various lengths. These were tongue and groove on diagonal planks and those on the joyces below. The tongue and groove oak was NOT nailed or glued. As the humidity changes the wood breathes - expands and contracts. A wood floor must be free to move. I sanded and refinished the oak when I moved in. It was in great shape to begin. It was in better shape when I finally sold.

Question: What is "Hickory Pecan"? Those are two very different woods with different grains.

Bob

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#16
In reply to #15

Re: OSB for Hardwood Flooring

01/16/2008 6:36 PM

Thank you so much for your reply...this helps tremendously! Also, if you go to this website you can see the flooring I have http://www.kentwoodfloors.com/content/productViewer.aspx?ID=152

Thanks again...R

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#17

Re: OSB for Hardwood Flooring

02/15/2017 4:31 AM

I don’t have exact answer for you but I know http://www.pcwoodfloors.com/locations/brooklyn where experts have years of experience in flooring and can solve your problems easily. Even I consulted them before having wooden floor finished at home and given them the order to place the best hardwood floors with proper installations and orientations.

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