no gap between hardi and walls problematic?

Old 07-05-05, 02:26 PM
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no gap between hardi and walls problematic?

Greetings to all,

My wife and I have decided to redo a small 5'x5' bathroom floor in 12"x12" tile. After a week of how-to research, and a week of on/off prep on the subfloor, we finally put down the first 2.5'x5' piece of Hardi backerboard yesterday afternoon.

Despite our week of research, we somehow missed the fact that folks recommend a 1/4" gap between the Hardi backerboard and walls to allow for expansion/contraction. So, one 5' side of the backerboard is flush against the vinyl tub, and a 20" segment on the opposite side is flush against a sink vanity. Otherwise, there is plenty of clearance around the two 2.5' ends, and the remainder of the 5' side (minus the 20" flush segment).

So, our question now is how critical is that 1/4" gap? We have the Hardi down over thinset, and screwed down every 6"-8", so removal at this point would be a pain. But if the two segments that are flush will definitely lead to problems in the future, well, I guess now is the time to take care of it. BTW, this is an upstairs bathroom over a wood floor and in the center of the house so it is relatively well insulated from thermal stresses. Thanks in advance for any advice!

Old 07-05-05, 05:58 PM
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You will probably be ok. Its the dimensional lumber in the walls that experiences seasonal movement so as long as you are not up against the stud plate in the wall you can breathe easier.
Old 07-05-05, 06:24 PM
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Thanks, Tileguybob, we appreciate your response.

We are thinking it probably won't be too much of a problem like you have suggested. But just to be safe, we will manually trim 1/4" off of the flush/abutting edges of the Hardi because it will certainly be easier now than after laying the tile...

Elsewhere someone suggested there might also be a "cosmetic" reason for doing so--if there is some expansion/movement and the Hardi rubs against the tub, it could actually lead to an annoying squeak.

So I guess we will bite the bullet on this one, and trim it out now just to avoid possible problems. Oh well, an extra couple of hours doesn't matter at this point--we have been floorless for about two weeks now. Thanks again, Tileguybob, for your response.


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