OSB Board, Tongue and Groove, which side up?


Jose Crammer


I'm installing some OSB board for flooring in my upstairs bedroom.

I'm not sure which side should face the joists and which side it is that you walk on.

I can't see any stamps or markings to indicate the correct orientation.

I need to know this before I commence with the project, hence I'm here to ask you guys who have experience and knowledge on installing these boards.

I've added some pictures to aid with my post.

Thank you for your help.



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I did say in my original OP, that I could not see any print. After a second glance, I can see some print, indicating information of the board. This is located on the side with the shorter tounge. I'm not sure if this is an indication for correct orientation, I did read online it can be in North America but I'm from the UK.

Thanks for your input foxhole, I did not want to lay them down to later find out I done it wrong and have to change them.
We use a lot of this stuff and keep the print out.
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We use a lot of this stuff and keep the print out.

Sorry, do you mean, you go shorter length tounge (print side) on top? Picture A? and Longer length tounge (None print side) to the joist, Picture B?
When using boards with this type of edging I have always put the wider edge to the underside supports
Who made the board? Is it “Norboard OSB3 Zero” by any chance?

I ask because this is their newish formaldehyde-free product and their docs say, I believe, that you should fit it with the writing down. Which surprised me when I read it, because I have some of their previous Norboard OSB3 and I’ve been putting it down with the writing up. Now I may be imagining but I think I’m doing that because some previous document said to. I have been meaning to do some digital archaeology to work out what happened.

Anyway - if you can identify the manufacturer, ask them!
Usually it is the thickest part of the grove edge down to the joist/support.

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