particle board in bathroom: code violation?

[hlwimmer]

question... we recently moved into a new construction in oakland, calif. -- new loft-y thing... affordable and convenient. while we love our home, we never liked the bathroom floor and are looking to replace it.

come to find out, the vinyl-composite tiles (VC tiles) that the builder used come right up -- almost no glue/mastic. worse yet is that the underlayment in both bathrooms is partlcle board (5/8in PB over 1/2-5/8 OSB subfloor).

question #1: is particle board (PB) approved for use in bathrooms? would the use of this in a 2-year-old construction be a code violation (i.e.: should it have been used in the first place)?

question #2: if we decide to keep the PB (i.e.: there is no present water damage) and coat it with a floor-specific waterproofer (redguard or similar elastomeric/rubberized coating), will it last at least another 10years?

question #3: we plan on replacing the VC-tiles with 1in hexagonal ceramic tiles... the floor is actually very stable (so sags or creaks)... after waterproofing like crazy, what are the opinions of the durability of the tile (when installed on the PB underlayment) (?)...

thanks for any wisdom...

[HayZee518]

Your subfloor is better off with particle board as it presents a greater density than plywood which is very porous. A silicone sealant would seal any pores in the particle board and present you with a good base for tile or lino.

[kactuskid]

You should install 1/2" cement board on top of the subflooring, installed using thinset morter and screwed in. Then install your ceramic tile using thinset, this provides a stable rigid foundation to prevent cracks from occurring due to flexing. Here's a link that'll help you with any questions.

http://www.thetiledoctor.com/howto/floorsinterior.cfm