Tub with a 1/4" "flange" [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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12-17-2016, 02:03 PM
Hello all,

I am doing a bathroom remodel and plan to reuse the existing tub. Oddly, the tub has only a slight (1/4") lip (not much of a flange). I already put in my CBU keeping it a 1/4" above the tub. My plan was to spray foam the gap, cut off the excess and tape and mud over the spray foam then waterproof the whole thing. After sleeping on it though, I feel less sure this will be a fool proof method.

To get the back of the CBU inside the "flange" I would need to make the cement board touch the tub (I thought 1/8-1/4 joint was preferred), and also fur out the entire wall because the tub was not set into the wall.

I'm just wondering how much all of this matters considering there was no issue with the old tile (other than aesthetics) and it was just set on sheet rock up to the tub with no vapor barrier even.

Thank you so much for you help everyone!

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Houston Remodeler
12-17-2016, 06:09 PM
The bond to the tub will be the tricky part. I'd use kerdi band with thinset to the CBU and Sikaflex to the tub. The RedGuard the whole thing.

12-19-2016, 10:29 AM
Seems like that oughta work. Thanks for the advice! I've never used sikaflex before, seems like a cheaper version of kerdifix huh?

Houston Remodeler
12-19-2016, 12:40 PM
We could argue all day about it, but in the end - yep. We use it all the time.

12-19-2016, 02:52 PM
There's a thread in the pro section on Sikaflex...read that, then decide.

12-19-2016, 06:29 PM
Looks good to me. Going with the sikaflex construction sealant. Didn't see the "1-A" stuff at home depot, but I think this is the same. Urethane based but I'll take my chances...