Tom Smeal

02:49AM | 03/18/04
Member Since: 02/02/04
13 lifetime posts
I just installed 1/2" wonderboard over our 5'X 5' bathroom floor (excluding bath/shower). Is it advisable to install 15lb roofing paper on top of the wonderboard before installing the new 12"X12" ceramic floor tiles?

I plan to seal the grout of course, but I just want the extra protection while I have the opportunity.

Thanks for any advice.



05:34PM | 03/18/04
Member Since: 03/15/04
28 lifetime posts
Don't think I've ever heard that suggestion, and don't know why you would think you need it. The backerboard is resistant to moisture. It will not deteriorate even when submerged. You're also going to have a layer of thinset that is basically a solid bed of cement over it, and then tile. If you're really concerned that moisture could soak into the plywood thru all that, and for your peace of mind, I would suggest you use a product like RedGuard. It's available at H.*me D.ep*t and is a roll-on waterproofing and anti-fracture membrane for ceramic tile.

Tom Smeal

03:42AM | 03/19/04
Member Since: 02/02/04
13 lifetime posts
The roofing felt idea came from a tile book I bought. It was suggested, along with the Red Guard option you mentioned.

Thanks for the advice.



08:31AM | 07/06/07
Member Since: 07/05/07
1 lifetime posts
i've heard that i should not use both roofing felt behind my backerboard and Red Guard on top. Something about mold development. Could you weigh in on this? I am working on a the walls surrounding an existing tub. Thought this would be the best way to ensure a waterproof wall.


07:39PM | 07/06/07
Member Since: 07/03/05
283 lifetime posts
By doing what you talked about you are encapsulating the cement board with no ability for it to breathe and exhaust any moisture buildup that might occur. There is still air between the cement board and the roffing paper. Condensation could occur when one side of the board gets warm while the other side stays cold. Cement boards do not promote the growth of mold as they are not a food source like a gypsum board would be. But other contaminents on the board or in contact with it could create an issue.

If you are doing a steam shower the paint on waterproofing should cover the cement board as you dont want steam vapors to collect behind the board. A regular tub/shower is usuually waterproffed from behind the board. Actually waterproofing is a misnomer because once a nail punctures the roofing paper or plastic sheet it is no longer waterproof. At that point we consider them to be moisture retardent.


Post a reply as Anonymous

Photo must be in JPG, GIF or PNG format and less than 5MB.


type the code from the image


Post_new_button or Login_button

A Washington State couple called on BC&J Architects to transform their 400-square-foot boathouse into a hub for family bea... Built on a rocky island in the Drina River, near the town of Bajina Basta, Serbia, this wooden house was cobbled together ... Large steel-framed windows flood the interior of this remodeled Michigan barn with daylight. The owners hired Northworks A... Edging formed with upside-down wine bottles is a refreshing change. Cleverly and artistically involving recycled materials... If you’re up for a weekend project, why not try turning an old picture frame into scaffolding for a living wall? Low-maint... Similar to the elevated utensil concept, hanging your pots and pans from a ceiling-mounted rack keeps them nearby and easy... For windows, doors, and mirrors that could use a little definition, the Naples Etched Glass Border adds a decorative flora... The thyme growing between these stepping stones adds a heady fragrance to strolls along this lush, low-maintenance garden ... Decoupage is an easy way to add any paper design to your switch plate, whether it is wallpaper, scrapbook paper, book page... Twine lanterns add pops of crafty—but sophisticated—flair to any outdoor setting. Wrap glue-soaked twine around a balloon ... When securely fastened to a tree or the ceiling of a porch, a pallet and some cushioning make the ideal place to lounge. V... Reluctant to throw away any of those unidentified keys in your junk drawer? Hang them from a few chains attached to a simp... A stripped-down model, sans screened porch, starts out at $79,000. Add the porch, a heated floor for the bath, and all the... Salvaged boards in varying widths and colors make up the dramatic accent wall in this attic space. The high-gloss white of... Need a window and a door in a tight space? A Dutch door with a window may be your answer. These useful doors are split hor...
Newsletter_icon Google_plus Facebook Twitter Pinterest Youtube Rss_icon