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another tile scenario/pool

updated fri 18 jan 02


linda blossom on wed 16 jan 02

Dear Craig,

I don't see how you are keeping the water in the pool. Cement backer board
does not degrade under water, but it also does not hold water. You have to
consider the grout as a place where water can get through. Backerboard
over plywood is fine for an area where a little water might get through like
on a counter top. In tub surrounds where water is more of an issue, a
waterproof barrier is needed behind the backerboard. In vertical
applications, backerboard does not have to go over plywood or other
substrate. In this application I would use a flexible, waterproof liner
intended to hold water like Nobleseal TS. Since you can tile directly to
Nobleseal, the backerboard is not necessary as you can bond the nobleseal
directly to the plywood. A good source for information on this is a book on
tile setting by Michael Byrne. This is a rather heavy thing to be moved one

I just reread this and you said that you would sheath the framing with the
cement board. Do you mean that you were not planning to use plywood first?
Cement board does not have the strength for this type of application and on
horizontal surfaces must be thinsetted to the substrate and in this case
even on the vertical. So if you were to use both the plywood and the
backerboard, you could only put a liner under the plywood which would not
work because it would be getting wet. I say that it would have to go under
the plywood because the backerboard must be bonded to the plywood. Someone
might say that you could use epoxy grout which would not allow water to get
through the grout lines but I would still want a liner. A little movement,
a little cracking and you have a leak which would not happen with the liner.

Ithaca, NY

----- Original Message -----
From: "Craig Martell"
To: Sent: Wednesday, January 16, 2002 3:11 PM
Subject: another tile scenario

> Dear tile gurus:
> I have to make a tile pool. The dimensions are 8ft x 3ft x 22inches
> deep. This thing has to be moveable too. So the way I'm thinking about
> approaching the job is as follows. It needs a fat rim so folks will have
> place to park their butts while they gaze at the fish or pick out the
> change for a bottle of Red Stripe. I am thinking of framing the pool with
> pressure treated 2 x 6s and placing the frame on a 4 x 4 base with cutouts
> for a pallet jack so moving will be easier. I will sheath the framing
> Duroc (cement board) and tile over this. Do any of you think I need to do
> anything to the Duroc other than apply mastic or mortar to set the tile?
> will, of course, seal the grout etc once the project is finished.
> thanx for any help, Craig Martell in Oregon
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