wonderboard on top of of sub-floor ??

[Andy S]

You were right Colbyt...I'm back.

Thanks everyone with the suggestions for changing of valves. It was actually fairly simple, the new valve fit perfectly with the existing pipe inlets with the inlets being threaded couplers. No leaks first time around!

Anyhow, while finishing up the taping of the Wonderboard around the bath/shower walls, I found rotten particle board around the base of the tub. The sub-floor is in good shape but, of course, I am having to replace the bad portions of particle board. Is there anything wrong with me replacing the bad particle board with 1/2' Wonderboard? I'm also going to tile the floor so I'm going to place on top of everything 1/4' Wonderboard (after tearing off 3 layers of *poor* quality linoleum to help with floor height issues).

Thanks again!

Andy S.

[Colbyt]

I would bite the bullet now and get all the particle board out of the bathroom. I can't think of any reason other than cost that you could not use 2 layers of wonderboard. I have found the hardiebacker product to be a tad easier to work with than wonderboard.

Colbyt

[LBaker]

Wonderboard has no structural value for floors. It is a decoupling system for tile installations. It must have a subfloorunder it.... From the manufacturer-

Subfloor Requirements: 5/8" (16 mm) exterior grade plywood or OSB panels (PRP-108) should be securely glued and fastened to floor joists. Floor joists framing should be spaced a maximum of 16" (40.6 cm) o.c. 3/4" (19 mm) exterior grade plywood or OSB subfloor framed with I-joists spaced a maximum of 19.2" (48.7 cm) o.c. or I-joists or truss system spaced a maximum of

24" (61 cm) o.c. are also acceptable. When setting dimensional stone larger than 12" x 12" (30 cm x 30 cm), a 3/4" (19 mm) subfloor must be used for all installations. All plywood or OSB subfloor sheets must be gapped 1/8" (3 mm). Installation: Using a 1/4" (6 mm) square-notch trowel, apply a setting bed of latex-modified mortar to the subfloor or base. Immediately laminate 1/2" WonderBoard to subfloor base, leaving a 1/8" - 3/16" (3 - 5 mm) space between boards at all joints and corners. Stagger joints so they do not line up with underlying substrate joints. Fasten backerboard every 6" - 8" (15.2 - 20.3 cm) o.c. throughout board field and around all edges while setting bed mortar is still workable. Around perimeter of each board, locate fasteners within 1/2" - 2" (1.3 - 5 cm) of edge. Fill all joints and corners solid with latexmodified mortar. Taping of floor joints are not required.

[Andy S]

Yea, that's what I'm thinking myself. I'm planning of removing the current vanity / sink and replacing with something more modern. With the vanity out, and it being a small bathroom, it won't take more than say 4 or 5 sheets to cover the whole bathroom floor. $100 for two layers, I can handle that.

[Andy S]

Thanks for the info...but like my original post indicated, I do have a sub floor that is in good condition. :)