OSB for subfloor

peter nap · August 28, 2007, 05:21:48 PM

My one experience using OSB for subfloor was bad. It swelled and I played the devil getting it flat. Has it gotten any better over the years?

My concern is that I won't be able to get it under roof for a couple of weeks between start and finish. With two helpers, I used to be able to do it in a weekend. This is different. I don't have any helpers and I'm 20 some years older.

It may get wet!

Kevin · August 28, 2007, 05:47:06 PM

I used 3/4 t&G OSB as my subfloor and it got wet. But once it dried out it was find.
Kevin

August 28, 2007, 07:17:17 PM

I have used 3/4" edge gold T&G OSB on the Oregon Coast with no problems. The local builders use it and recommend it.

mt

MikeT · August 28, 2007, 07:23:28 PM

I have used 3/4" edge gold T&G OSB on the Oregon Coast with no problems. The local builders use it and recommend it.

mt

PA-Builder · August 28, 2007, 07:23:46 PM

If Advantech is available in your area, I would definitely use it. I used 3/4" T&G, and with numerous soakings, absolutely no problems. In my opinion, the best OSB product available. And no, I am not a salesman !

August 29, 2007, 06:56:42 AM

I used the 3/4" Advantech product too and mine did get wet. But once it dried, there seemed to be no problems!

MikeT · August 29, 2007, 08:50:22 AM

I should add that on my OSB subflooring on the rainy Oregon Coast, the local builders just look at where water is pooling on the OSB and either take a big swing with the claw end of a hammer or drill a 3/4" hole or three where the water is collecting...

mt

davidj · April 30, 2009, 06:24:22 PM

A brief article on the comparison of Advantech, Gold Edge, Plywood and regular OSB:

http://www.utextension.utk.edu/publications/wfiles/W176.pdf

Don_P · April 30, 2009, 09:03:51 PM

One thing the study doesn't show in the graph, (and I just quickly skimmed the article), the reason I switched to Advantech was delams in plywood. I don't particularly mind running a floor sander over the edges of advantech if the house sits open for a few months but a delaminated sheet of plywood is a sheet that needs to come back up. I replaced 9 sheets on one house , 3 on another and 13 on a house that had been abandoned and was open for quite awhile. Replacing sheets that have been well glued and nailed down is a bear. If I know its a large job that will sit open for awhile we get some mismixed oil base paint or porch paint and do the floor. Some folks don't like the thought of a sheet of osb that is just held together by glue, but really a glue failure in either osb or ply is a total failure. There is also diagonal board sheathing.

May 01, 2009, 08:09:09 AM

In a do-it-yourself project where things (such as the roof) can get a bit delayed, you may want to try a different approach that I use: Instead of installing a continous "permanent" plywood flooring system ... install a temporary flooring system of regular porch decking (5/4"thick x 6"wide x length) directly to the floor joists. Keep the decked area "inside" the walls by a gap of an inch or more. Use just enough decking and screws to make a safe working floor ... 1" gaps between boards, etc ... let air and rain pass freely thru ... but leave no large holes, or loose boards, for folks to fall thru.

After the building walls and roof are in place, you can remove the temp flooring and install the final version of subflooring, etc without the worry of weather exposure. You will have to make extra stiffening provisions around the floor perimeter as the original total "floor membrane" concept is lost and must be corrected for ... I don't find this a big deal ... but it can't be overlooked.

If you have a porch in your house plans, the decking just gets moved, a short distance, to the porch area after it is removed from inside. With a bit of planning, the deck boards can be relocated, from inside to outside, and reused with no additional cut-waste.

I personally do not care for OSB. Would rather pay the additional bucks for better weathering ability.

ScottA · May 01, 2009, 08:51:45 AM

Mine got rained on for 3 months and turned out fine. Just needed a little edge sanding.

MountainDon · May 01, 2009, 09:48:14 AM

Maybe a year ago we had a discussion on the merits, and demerits, of installing the subfloor the way JRR described. I can't find the topic, but I believe PEG had several things to say about it. All bad or at the best discouraging. I also touched on this recently in the topic on ETBass's vertical log cabin video, as far my own personal uncertainty.

To me, a building with this modified sub floor idea would not have as solid a wall to floor connection. I have nothing to back that up, it's more a feeling.

One thing that comes to mind as a negative is the reduced amount of bottom plate that would extend above the flooring; not as much to nail trim to.

Sure would be nice to have some more input from an engineer or other seasoned builders...

OldDog · May 01, 2009, 08:03:37 PM

DON'T DO IT

JRR · May 01, 2009, 10:13:03 PM

"The name comes from a French Missouri type of construction, "maison en boulin." [2] The curious name of this framing technique is conventionally thought to be a derisive one. Historians have fabricated the following story: As Taylor was constructing his first such building, St. Mary's Church, in 1833, skilled carpenters looked on at the comparatively thin framing members, all held together with nails, and declared this method of construction to be no more substantial than a balloon. It would surely blow over in the next wind! Though the criticism proved baseless, the name stuck."

I'm reminded of this above story ... you can find the rest of it in Wikipedia.

If in a platform framing job, one storey is placed on another without the intermediate flooring membrane being first installed in the usual fashion and usual order ... are you folks telling me that there is no way to later install the floor (plywood) membrane, even after the roof and walls are fully assembled ... and make a safe and satisfactory finished product ... fully as strong as if the ply flooring had been installed "the normal way" (my quotes for emphasis)?

Hmmm ....

JRR · May 01, 2009, 11:28:08 PM

Its getting late. I gonna give one answer to my own question ... there is no way to later install the floor (plywood) membrane??

Mind game time: Let's imagine a set of house plans (from John, of course) for one of his larger two storey houses with no load bearing interior walls . Look at the sheet (hopefully there is such a sheet) that shows the plywood/osb flooring scheme that goes between the top plate of the first floor and the bottom plate of the second floor. Mark the layout of those sheets, or pieces of sheets, that make up the "perimeter" ... around the outside of the building. Plan to first install just these perimeter pieces. (Hey, its a start!)

Mind game extension: Redraw John's flooring layout so that each of the perimeter pieces is 1/2 sheet or shorter. Now plan to first install just these smaller perimeter pieces. (Whee! ... I think I can pedal by myself now ....!)