Fox's Fantastic Fixer-Upper

Bottom Line Up Front (BLUF): How smooth does the subfloor need to be before you put down backer board?

Long version: Renovating the bathroom. Ripped up the vinyl and found a layer of 12" linoleum tiles on top of a sheet of linoleum (except the 2'x4' area where the old vanity was). So I started chiseling it up.

It was really slow going because the linoleum tiles were brittle and were flaking instead of coming up in big pieces. Then I noticed that the surface color actually appeared to be grey (it was hard to tell with the glue on them) and that, instead of being black like regular linoleum, the whole tiles were grey all the way through. Then I realized that they weren't, in fact, regular 12" squares. They were rectangles of varied dimensions. Finally it hit me : The "tile" was actually 1/4" backer board!

So now I've got a bathroom where the middle 1/2 is stripped (more or less) down to the wood. And the end 1/4s are covered with a sheet of linoleum under 1/4" cement backer board. (You lay down cement backer board to give a smooth, strong, flat surface to put your tile on.

At this point am I stuck pulling up the rest of the floor, or can I just put down a layer of thinset before I install my backer board to provide an even surface for tiling. How smooth does the floor under the backer board need to be anyway, because with the irregularities of the wood and the areas where the face of the linoleum came up, but the rest of it remained glued to the floor, it could be an involved project to get my floor perfectly smooth.

Re: Tileforge-bathroom advice...

What type of flooring are you putting on top of the backer boards?

Re: Tileforge-bathroom advice...

Ceramic tile.

For those of you keeping score at home, all the DiY sites say you need to get your subfloor layer absolutely flat.

A few advocate laying down 1/2" plywood if it is a board floor, and a good many say you should also have a vapor barrier of either plastic or roofing felt.

That said, most of the sites advise you to put down a layer of thinset "to fill the voids in the subfloor". To me that says your subfloor isn't perfectly smooth.

I plan to leave the existing backer board in place and try to mesh up the new stuff with it. Stupid? Possibly. Lazy? Probably. But I'm going to try it.

(Oh, and to my defense, part of the reason I didn't realize it was backer board right away is that it is simply glued in place. It should have screws every 8" and the joints should be taped.)

Re: Tileforge-bathroom advice...

My builder friend says you need to finish the job rather than patch to get a good result as weight-bearing ceramic tiles are unforgiving. Plus the old backer boards may not work with the new backer board (differing flexibility and 'cure').

The reason you need the subfloor absolutely flat is that the backer will take the shape of it, so you may end up uneven or with cracked grout and fractures on the tiles.

I dunno about this stuff, so I can only pass on his opinion.

Re: Tileforge-bathroom advice...

Ceramic tiles are a pain in the ass.

As far as I'm concerned, all flooring should be sealed concrete with maybe an area rug or two.

And floor drains in every room.

Re: Tileforge-bathroom advice...

That sounds like a dog kennel.

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Maybe, but it's also eminently practical.

I actually saw part of some remodeling show where they did countertops in concrete, too.

I guess I'm probably the only person who would want to live in a house I designed.

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Actually, in my old-old house, we had a pantry with polished concrete worktop. This was because the pantry was a funny shape and the owners before us had done it as a normal laminate one wouldn't fit right without hacking it to pieces first.

But yeah, I can't say I'd want to try and sell a UA house. Target market population: 1.

Re: Tileforge-bathroom advice...

Have you considered prison?

Barring that, maybe a zoo. But only one of them old-style "inhumane" zoos.

Re: Tileforge-bathroom advice...

Ugh. Thanks. This is almost certainly good advice, but I think I'll pick up a couple sheets and maybe dry fit them to see just how close I am.

The two things I've got going for me is that its a pretty small bathroom (like around 4'x9', not including the tub) and the tile I've selected is small tiles (its one of these ones where you have a pattern fixed to a 12"x12" mesh) so it should handle minor floor irregularities better than great big tiles.

Re: Tileforge-bathroom advice...

Considered it an inevitability at times, but it's nothing I look forward to.

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I want to build a cube-shaped house out of steel I-beams and cinder blocks, with all the flooring, stairs, counter tops, etc. done in concrete. No paint. Exposed pipes and electrical conduits. No structural or cosmetic wood at all. Every appliance some kind of rust-proof metal.

Re: Tileforge-bathroom advice...

Major heat sink in the winter... your heating bills will skyrocket. Area rugs will collect mildew pretty quick under there too. All that mildew will in turn diminish your lung capacity and build up, meaning you'll hack more tokes than an asthmatic teenager. Further, your bones will be feelign the cold and damp more, meaning it'll up your intake.

Think of all the wasted weed before eschewing actual floors.

Re: Tileforge-bathroom advice...

I'll mention this to my better. Aenea is a tile ninja.

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Jesus man, a hot wife who's a crack shot AND can install tile!? I don't know why you ever leave the house.

Re: Tileforge-bathroom advice...

If you are going to be doing the small tiles then sure use the self-leveler or something like it to fill the hole, then cover with cement board.

However remember for re-sale value you may have to dig out or have dug out all layers if it cracks.

And to spaceturkey if you make the concrete out of insulated concrete the R factor is awesome. I want to do it myself one-day...well pay someone to make a house out of concrete. In fact I talked to a guy about it the other day. As for concrete floors a plastic vapor barrier put down before the concrete is poured would take take care of any moisture and would help the concrete to cure slower thus making a stronger concrete.

Re: Tileforge-bathroom advice...

Gah. I'd-a figgered small tiles would be more forgiving than large ones--less likely to crack and all.

Turns out the stuff I thought was backer board isn't. No idea what the hell it is, but its way too thin to be backer board. So its coming up. On the plus side I picked up this scraper dingus that is doing a pretty good job on the linoleum remnants.

I did pick up some "self-leveler" stuff, but I was thinking about returning it. I mean basically the stuff is thin concrete. You mix it up, pour it on the floor, and then wait for it to dry. And since I've got a board floor I'd be putting it on I'd need some kind of waterproof layer.

The final concern is ceiling height. Just replacing the vinyl and lino with ceramic and backer board, I'm losing almost 1/4" of headspace. That may not sound like much, but the interior doors are already cut down from standard size and I'd hate to have to cut them down more (but I may have to ).

Re: Tileforge-bathroom advice...

A self-leveling compound works wonders for uneven bases.

We've laid tile directly upon our homes foundation and upon our counter tops, no cement board was necessary in either instance. Tile size matters insofar as larger tiles are more rigid, whereas smaller tiles (especially those adhered to a mesh design) are much more flexible. Keep these qualities in mind when choosing the proper tile for a specific application

Re: Tileforge-bathroom advice...

Intriguing. That was my take on the matter as well. If one put in the self-leveling compound, you were basically pouring the equivalent of cement board.

OK. Next question: Because I don't have a plywood subfloor--its boards--I was planning on using 6mil plastic under the self-leveling compound. With backer board, you screw the bugger down every 8 inches--AND put thinset under it. If I go with self-leveling compound, I wouldn't be screwing that down, right?

I'm thinking even with a moisture barrier in, if I use self-leveling compound to a thickness of 1/4" it'll pretty much hold itself in place, being one monolithic chunk instead of composed of screwed in pieces, taped at the seams.

Re: Tileforge-bathroom advice...

My point being that if he was just going to fill the whole, the wood floor underneath could still move and since old and new cement don't necessarily bond well they could move independent of one another and cracking would ensue.

Re: Tileforge-bathroom advice...

Painting is done. Decided to defer the floor until after the tub surround. Since no one will be walking on the walls, it looks like that'll be a simpler project. Besides, I had to tear out the old plastic tub surround to do the painting so it'll minimize my inconvenience by getting it out of the way. It'll also minimize the chance of messing up the new floors with the tub tiling.

Re: Tileforge-bathroom advice...

Well I may have fucked myself. The DiY sites on cement board installation are all very good at saying to allow a gap at the tub edge for expansion, but the tile sites don't mention it. And after carrying out a sizable chunk of plywood with old tile on it and thinking "Damn, this is heavy." I installed the bottom course of tile flush with the top of the tub so the wall wouldn't have to carry the whole weight of the tile, mortar, and cement board.

Cast iron tub with a porcelain finish. First time I fill it, the fucker'll probably expand and pop my bottom row of tiles.

Re: Tileforge-bathroom advice...

Tub surround is almost done. Once the grout dries, I get to "wipe off cloudiness" Judging from a quick test I did on a tile just now, that'll take about a year and a half. Maybe it'll come off better once it is drier.

Anyhow, I thought I'd made a decision on the floor, but I'm having second thoughts. I was planning to get some roofing felt, staple it down to the floor, and pour in the self-leveling compound on that. But nowhere on the Internet have I heard anyone say that'd be a good idea and the SLC packaging is emphatic about install conditions. So I'm leaning towards 1/4" backer board again.

Re: Tileforge-bathroom advice...

Men are so adorably persistent with DIY.

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Yea.... the dryer the grout the harder it is to get off. Soooooo good luck.

Also the more natural and poris the tile the harder it is to get off, you have to seal it first.

Re: Tileforge-bathroom advice...

Yea, get the grout cleaned up...

[action=Caboose]looks, post was three days ago...[/action]

I hope you got it off by now, if not it may take an acid wash to do it.

Re: Tileforge-bathroom advice...

I had a shower/tub job that I tweaked my back really bad on just after getting it grouted and couldn't get it finished since I was all but incapacitated.


Man, there's nothing like washing and scrubbing tile with muratic acid to get the grout off but after choking on the crap for a couple of hours I managed to get it cleaned up.
This was like over a week later when I could move again.
Homeowners were cool with it when I was done, they weren't too sure I could make it right but I quickly dispelled their fears.

Re: Tileforge-bathroom advice...

It turned out pretty well. I pretty much ignored the instructions and used a damp cloth and it worked fine, although it isn't something I want to do anytime soon. And I've taken a couple baths and showers and (knock on wood) the tile seems good to go. Still gotta caulk the corners and edges.

I think I mentioned upthread that the walls aren't true, so as a transition I'm going to use some of that cheap foam trim. Obviously they make wood mouldings--usually in oak, pine, or hemlock here. Then, a step down from the pine is MDF, a sort of "particle board" that comes primed white and is paintable. At the bottom end is this foam crap with a printed plastic sheet cladding over it. You can get that in white or in various fake wood patterns.

I've always looked down on it, but in retrospect it is cheap, easy to work with, completely water resistant, and won't warp. Perfect stuff for camouflaging bathroom tile transitions.

Re: Tileforge-bathroom advice...

The foam trim is cheap but functional for the short term.

Let everything dry out good before you caulk it in.

You may want to consider sealing the grout as well.

Is the tile wall hanging in space there to the left?