OSB ...slick side in/out & up/down?

[Guest]

I am a carpenter and teach vocational carpentry at a vo-tech. Often, when I show apprentice carpenters something I have done for years, I hear "Why?". Most of the time I can give them answers I'm confident of. However, occasionally, I'm not sure ... other than "that's the way I learned" and "that's the way we have always done it". To provide a better answer, I usually contact other carpenters or manufacturers or head to the library to "teach" the teacher. I thought I would give "FORUM" a shot at providing an answer to a question that is asked every time we sheath walls or deck floors with OSB. "Why is one side slick and one side rough?" and "Which side goes down on floors (rough / slick) and which goes in to the structure (rough / slick)?" I'm interested in the different answers from "FORUM" ... I've received some interesting and different responses from seasoned carpenters.
Thanks Jim

[Guest]

Re: OSB ...slick side in/out & up/down?

Slick side down on floors and roofs. It helps prevents falls.

Slick side inside on walls so you can see the colored nailing lines.

I sure wish they would put those lines on plywood.

[Guest]

Re: OSB ...slick side in/out & up/down?

rough side to exterior. same as above, prevents falls on thr roof and I was under the impression it had a certain amount of waterproofing on it to help keep it from delaminating during the rough-in stage.

[Guest]

Re: OSB ...slick side in/out & up/down?

If you want to know why physically one side is rough and the other side is smooth - it originates in the manufacturing process. Strands are deposited on screens in the forming or orienting process (hence oriented strand board). The screens are typically a little over 8'x24' (yields six 4'x8's)to fit a typical multi-daylight press. The screens act much like cookie sheets. They are used to convey the oriented strands - face layers parallel to the forming direction & core layer perpendicular to the forming direction (now called a mat) into the press. The typical multi-daylight press has 12 to 14 openings. Each opening or platen face is smooth. The mats are conveyed into the press on the screens where they are pressed/consolidated into boards. While in the press oneside of the board receives the imprint from the screen and the other side receives the imprint (or lack of) from the smooth platen. There are new nonmulti-daylight press or continuous presses being used where screens are not essential to the board making process, but are used solely to imprint the screen or rough side on the board.

[Guest]

Re: OSB ...slick side in/out & up/down?

Thanks, Gord. I always thought there was some hi-tech, critical design reason for the difference, and it was probably a big trade secret.

As for which side up, Jim, on the material I get it is written on the board in some of that barely legible black print. Yeah, I know, somebody had to show me too.

Then I called the Mfr. and they verified the direction, but had no explanation for the difference in textures.

[Guest]

Re: OSB ...slick side in/out & up/down?

When OSB first came out it was slick on both sides. Try to use that on a roof surface!! Then they came out with sort of a knurled finish on one side, I thought for safety reasons, and now it is just more of a fuzzy surface for the same reason. I had people wanting to use it for paneling in houses, because it had such a smooth shiny surface with all the wood chips, only one side had the printing on it. It did look nice, a little rustic.

[Guest]

Re: OSB ...slick side in/out & up/down?

OSB should be installed with the slick side inside on walls and roofs and fuzz up on floors. I use Weyehouser OSB which has lines at 16"o.c. and 24" o.c. which saves a lot of time.

One other thing to consider on all panels used in framing is that your building inspector should always be able to read the information printed on the panels. Another thing to consider is if you have a problem with the panel, a rep needs to be able to read the print also to verify that it is his product as well as when and where it was made for QC.

[Guest]

Re: OSB ...slick side in/out & up/down?

Don't matter to me which way it's stacked at the lumberyard, because that's where it's going to stay as far as I'm concerned.

[Guest]

Re: OSB ...slick side in/out & up/down?

Slick side down on roofs floors slick side out on walls I do this because there is less swelling and nails don't overdrive as much. and I've never heard of an inspector questioning osb except when it first started getting popular years ago

in Portland _Rob