# Curved backerboard?



## mdalli (Jun 29, 2006)

I'm using something called "Easyboard" from the Home Depot, which is much lighter and easier to cut than traditional cement backerboard. But I think I'd have this problem even if I was using traditional backerboard.

The problem is that the bottom edge of the backerboard lays up against the top edge of the bathtub, which causes the backerboard to curve ever so slightly outward towards the bottom.

My question: is this going to be a problem? Should I have done it differently?


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## gregzoll (Dec 25, 2006)

You do not lay it to the edge of the tub, leave about 1/4" from the top edge of the tub, and the Backerboard. From there, when you lay the tile, you leave a small gap to allow for Silcone to be placed between the tile and the tub. This way moisture if it ever gets through, will not seep up through the Backerboard.


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## mdalli (Jun 29, 2006)

Like this (see attached crude drawing)? Or should the tiles go further up or down against the backerboard?


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## gregzoll (Dec 25, 2006)

Just like that, but the Tile should not go over the basin of the tub, where there is a potential for water to get up under it. Keep in mind, that the lip of the tub is there for a reason, and placing material over will cause problems.

The lowest point should be even with the top edge of the tub, with just enough room for the caulk to meet the edge (ie 1/4" for both backer & tile).


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## jerryh3 (Dec 10, 2007)

gregzoll said:


> Just like that, but the Tile should not go over the basin of the tub, where there is a potential for water to get up under it. Keep in mind, that the lip of the tub is there for a reason, and placing material over will cause problems.
> 
> The lowest point should be even with the top edge of the tub, with just enough room for the caulk to meet the edge (ie 1/4" for both backer & tile).


Are you saying that the tile should not come below the top of the tube flange?


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## NateHanson (Apr 15, 2007)

I think his drawing is of the tub flange, and the top edge of the tub. 

The tile should come down over the flange to within 1/4" of the top surface of the tub. Caulk that gap with silicone. 

To avoid the bowing of the backerboard where it goes over the tub flange, either cut the backerboard to be above the flange, and tile over the flange (won't work if you're using small tiles, or the flange is unusually wide), or shim the studs above the flange, so the backerboard doesn't curve so abruptly.


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## mdalli (Jun 29, 2006)

NateHanson said:


> I think his drawing is of the tub flange, and the top edge of the tub.


Yes, that's correct. I removed the 2 pieces of backerboard that I had put up, and I noticed that the backerboard is the same thickness as the lip (which I reflected in my drawing).

I guess the only question now is this: exactly where should the tiles sit in relation to the tub lip?


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## jerryh3 (Dec 10, 2007)

mdalli said:


> Yes, that's correct. I removed the 2 pieces of backerboard that I had put up, and I noticed that the backerboard is the same thickness as the lip (which I reflected in my drawing).
> 
> I guess the only question now is this: exactly where should the tiles sit in relation to the tub lip?


The tile should come within 1/4" -1/8" from the tub surface. Fill the gap with a high quality silicone tub and tile caulk. Fill the tub with water before you caulk and let it sit like that overnight while the caulk is drying.


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