Tile/carpet threshold question - xpost w/ remodeling forum

12 years ago

I already posted one question about our forced bathroom remodel but I have another.

We've wanted to replace the vinyl floor in this bathroom with a heated tile floor for ages. It's cantilevered over the deck below and it always seems cold in there. Anyhoo, that's our rationalization because if their bathroom gets heated tiled floors, then our bathroom gets them, too. ;-)

The builder did not install underlayment in our 2nd floor (and may not have in our downstairs either, for all I know). All we have is subfloor. The builder gave us some blather about how not installing an underlayment would mean no squeaky floors (BS, we have squeaky floors) but I think it was because he was trying to make a bit more money off us. Water under the bridge, moving on....

Without underlayment, I'm wondering if we're going to have issues with getting the new heated tile floor to mesh with our carpeted hallway or if we'll have a noticeable difference in height between the two types of flooring. I can manipulate that a little bit with new pad and carpeting (carpeting was also ruined in this area, plus it's 17 1/2 years old so time to go) but will it be enough? Would it be a good idea to install underlayment when we replace the carpeting? Or would that create more problems than it's worth? I know we'd have issues at the stairs so we'd have to figure that out and doors would need to be shaved a bit, plus molding moved up (but we plan to update that, too since we plan to stay put for 10-15 more years). No clue how to do this and would rather not bring this up to our contractor until I know whether this is a hair-brained idea or worth pursuing.

The other approach is to give the tile floor as low a profile as possible. But how low can I go? 1/4" thick cementious board (see, Bill, I did read your FAQ page, thank you!) plus 1/4" for heated floor system (think that's what the contractor said) plus the tile thickness.

Any advice?

Thanks!!

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Comments (4)

fnmroberts
12 years ago
It sounds like you have several issues:
A) Squeeks
B) Cold Floors
C) Concern about floor level differences

Regarding A, the builder is basically correct - 3/4 OSB is a building standard now. It is tongue and groove and glued down and together. Over time is will begin to squeek. You know where the squeeks are and when removing existing flooring, nail the subfloor tight again. Should eliminate, or at least reduce the squeek.

Regarding B, See if you can have foam insulation injected into the cantilevered space. As to heating, it still may be necessary but why not minimize its burden by controlling the root cause.

Regarding C, Several things here. Your current vinyl should be installed on a thin underlayment. Combined they are about 1/4" thick. It will be necessary to remove these. (This will be the time to inject foam insulation) A tile floor needs 1.25" minimum structural support which means a 1/2" thickness of concrete board will be cemented and screwed atop the existing subfloor. Then your heating mat followed by tile. So, you'll be gaining about 3/4" above the current level. Your tile shop will have a marble threshold with a beveled edge to minimize this effect. We have this same situation is our home and it is negligable. You may or may not have to trim the door.

Base trim would be removed in the bath to do this work. It can then be reinstalled, replaced or have the tile setter install tile as base trim - that's what we did.

Here is a link to an updated bath we did and amongst the photos you can see the threshold and tile base trim.

Hope this helps. Good luck.

Here is a link that might be useful: Bathroom
lisa_a
Original Author
12 years ago
Thanks for the photos (lovely bathroom!) and the suggestion to use foam insulation. We have considered that but haven't pursued it as yet but we can do that once the plumbing work is completed (they need to repair and move the toilet plumbing line and it's easier to do that work with the deck ceiling exposed). That's only part of why we want to do heated floors, though. Tile floors stay colder than vinyl (lived with tile floors in Florida) so they're not nearly as nice to walk on in cold weather.

Our vinyl was installed on 1/2" plywood underlayment, not 1/4". I know because most of it is was ripped up when the restoration company was drying out our house from the flood (the crew was really surprised to discover that the underlayment wasn't OSB or MDF). And, according to Bill Vincent's FAQ post here, we should be able to use 1/4" cementious board not 1/2". So it sounds like my difference may only be 1/2". We're using through-body porcelain tile so we can bullnose the edge if necessary. But I'd still like to see if I can reduce that difference a little more.

Our subfloor is plywood, not OSB tongue and groove. Or are you talking about the underlayment? At the time our home was built, I'm pretty sure the standard was the same as the bathroom floor's thickness - 1/2" - and OSB was the most common material, not plywood, but both were laid in sheets not tongue and groove. No idea what's standard in our area now or whether it's the same as where you are. Do you know that this is a national and not a local standard?
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fnmroberts
12 years ago
All of your vinyl and underlayment should be removed to the sub-floor before installing tile.

I have no idea about building codes in various parts of the county. The thickness of the subfloor would be affected by the on-center span of the floor joists - ie 12" span would not require as heavy of subflooring as 16" or 24". Plywood may be somewhat stronger than OSB, I don't know but suspect it might be. Our sub floors are 3/4" T&G OSB glued and screwed to 16" on-center engineered wood I-beams. Circa 1995, pretty solid, and I assure you the builder didn't spend more than necessry.

But, a tile floor MUST be solid as any flex will cause the grout to crack (possibly tiles too). Especially undesirable since you plan an electric heating mat below the tile. Again, I've always been of the understanding that 1.25" is necessary below tile and on that basis, 1/4" concrete board would be insufficient if you only have 1/2" subfloors. Your tile shop can guide you better.
lisa_a
Original Author
12 years ago
Sorry for misleading you about the underlayment and subfloor (I'm tired, not thinking clearly all the time).

The only part left of the underlayment in the bathroom is what's under the tub and under the vanity. Both pieces will go once the tub and vanity are removed. That was 1/2" plywood. There isn't any vinyl left in that bathroom. It all had to be removed as part of the water damage restoration work.

I'd have to go measure the subfloor to know what thickness it is for sure but I believe it is 3/4". Whatever thickness it is, it will be replaced in the bathroom because the restoration crew had to drill holes in it and then cut a huge piece out of it to determine if the insulation was wet (it was saturated) before they ripped apart the deck ceiling. Our home is also 16" on-center beams.

I know that a tile floor MUST be solid, that flex and tile is not a good combination but others following along with this thread may not know.