# OSB subflooring



## jogr (Jul 24, 2007)

Particle board to me is more of a filler than a structural element so if it is really particle board you are replacing then just about anything will work.

As far as using osb structurally on floors you want to be sure and orient it lengthwise across the joists but I don't think the side up matters for hardwood underlayment.


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## NailedIt (Jun 19, 2009)

The only time that matters is when you're decking a roof. If you put the shiny side up, you or someone you work with or FOR... will end up sliding off the roof. Other than that, there are lines on some currently produced OSB sheets for helping with nailing patterns which are only marked on the rough side.


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## PaliBob (Jun 11, 2008)

r, Welcome to the Forum
It doesn't make any difference from a structural standpoint. However if the OSB has tongue & groove edges then all the panels have to be laid with the same side up or down as the case may be so that the profile grooves will match.

Answers to some general OSB floor sheathing questions:
http://osbguide.tecotested.com/faq16

and some OSB FAQ
http://osbguide.tecotested.com/osbfaqs 
.


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## Gary in WA (Mar 11, 2009)

I don't know if it makes a difference structurally. 1. The installation instructions that PaliBob sited say "label down" -- so you will be voiding the warranty. 2. In construction the Building Inspector checks for the visible label, up at the roof and second floor for the rating and span listed per application. The colored layout lines also tell an inspector the framer installed a half sheet with the strength axis wrong if he sees them running perpendicular to the trusses/rafters from below. The waxed side is from manufacturing for easy release from the press. 
Be safe, Gary


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## PaliBob (Jun 11, 2008)

GBR in WA said:


> ........ The waxed side is from manufacturing for *easy release* from the press. Be safe, Gary


 Wow, Thanks Gary, I wondered why one side was waxed.

I cribbed my "Don't Matter" response in post #4 from Tommy @TOH
http://www.thisoldhouse.com/toh/asktoh/question/0,,430695,00.html 
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