thanks, I was able upload a photo. This forum is awesome...
-- I'm going to go with laminate which is inexpensive, easy to do-it-yourself, lasts a long time and looks great. Reason for not tiling: my joists are 48 inch o.c. so i would need to
add additional support and, since I don't believe in cutting corners, I'd have to remove the rest of the hardwood and replace with the proper substrate.
The new subfloor is 1-1/2 inch T&G planks (pine) the old stuff is actually a full 1-5/8 really solid fir -- I think this type of floor is called "western" construction and is common for older houses here, ours was built in the '59-- the hardwood is solid 7/16 inch oak, not plywood with veneer -- what a difference 50 years makes.
So why is hardi NOT allowed here (as seems to be the case)? We were planning to remodel another bathroom, but maybe we'll hire a pro this time and have him do a real mud wall.
After all the last bathroom makeover only took me 15 years or so.
Edit: I did a bit of online research and although its not apparent from the hardibacker instructions, I think that hardi is NOT recommended with T&G planks due to different expansion rates -- My reasoning is that if you securely attach one structure (the tile and cbu) to another that is expanding and contracting at a different rate (the subfloor), this results in the entire floor bowing up and down as temperature and humidity change, this causes all sorts of problems with tiles. In one direction the subflooring can give because of the T&G, but in the lengthwise direction it cannot. I guess if you use plywood it has roughly the same expansion properties as the subfloor, so in this case, the tiles simply move apart or together a tiny amount, which is taken up mostly by the grout. I don't understand why cbu on top of thinset and plywood is OK, though. Why wouldn't this result in trying to bend the tiles. In any case this hasn't been a problem in my bathroom because I don't have a tile floor and its only a 6x6 ft area, -- so far no indication that the vinyl or flooring are failing in any way.
I guess I'll bite the bullet and get some plywood. I can use the hardiboard on the bathroom walls (I'll make sure the substrate is correct this time).
Another question: Is it a good idea to apply some sort of anti-rot preservative and/or water sealant to the new subfloor in the area around the external door where the water came in (was an old wood french door, and there were some roof issues) -- it could happen again but I'm going to do my best to not allow water in.
Last edited by rrando; 06-07-2009 at 10:14 AM.