Question About Cement Backer Board

[RossB]

So I've started my project (600 sq feet total). I'll post pictures when I get a chance. Anyways, I have a question. I’m laying down cement backer board (WonderBoard) And I’ve come to a hallway and it would be very convenient for me to change the direction that I’m laying it to be perpendicular to the other backer board. If I don’t change the direction I’ll have to make a lot more cuts in the backer board. Is there a ‘grain’ the backer board? Does it matter if I start laying it in another direction? And at the end of the hallway I would probably change it back to the original orientation.

Thanks for your help

RossB

[John Bridge]

Hey Ross,

I'm not the best guy around here to be talking about backer board to, but there's a chance the joists in the hallway are turned perpendicular to the others anyway. You're supposed to run the backer in the same direction the plywood or other subflooring is running (across the joists), but at the same time they tell us the backer board doesn't do anything to strengthen the floor anyway. I honestly don't think it makes a big difference.

We should wait for more experienced people to respond, though.

John

Hi Ross

I asked the same question of several people in the industry, and the consensus was that there is no prefered orientation for the board. It is more important to lay the sheets out so that the edges of cement board don't get close the the edges of the plywood underlayment. When I asked for a figure for this , I was told "about 6 inches or so".

So that's the figure I have tried to use.

By all means, lay your sheets out to minimize waste.

Rob

[Tom]

To add to what Rob said, there is no grain in cbu's or cement boards, but aside from keeping the seams away from the seams of the plywood substrate, you also have to try to not have 4 corners of boards meet together. Stagger boards so that 2 corners meet with either the long or short side of the next board.

Tom

Good point. Thanks for adding that.

Rob

[Sonnie Layne]

Now I'm wondering.... after recently discovering that there is a "grain" to gypsum panels tho' it's never been disclosed by the manufacturers to me. Not really a big deal in the application we're discussing but...

Sonnie "the wanderer, errr, umm the wonderer" Layne