tile over tile - with a twist

Okay, here's the problem. I have a 12x32' den which at some time in the past was apparently an outside porch with a 4" concrete slab floor. This thing is covered in asbestos tile stuck down to the concrete. I would like to put down some sort of ceramic tile, not sure what yet, sort of leaning toward saltillo for a "rustic" look. If I succeed it's sure going to be rustic as the concrete is also sloping and I'm not about to try to level a 12x32 space! How am I going to get tile over that asbestos? Is thinset going to stick? Obviously I can't rough up the existing asbestos tiles. 1/4" backerboard? How would I attach that? The floor is mostly flat. Just sloping.

It's never easy .

 

Hi Cindy,

Have you tried removing any of the tiles? Sometimes they come up quite easily. The danger from asbestos is from breathing airborne particles, and not much will be airborne really if the tiles come up. Wear a dust mask.

Now I know someone will probably jump me for saying this. I'm ready.

John

http://www.johnbridge.com

 

Tile over this type of tile isn't a good idea. It will pop like crackers in no time.

Take up the asbestos tiles with a floor scraper while an assistant sprays a fine mist over the working area. They will come up pretty easily.

The remaining black adhesive is also loaded with asbestos and nothing will stick to it very long. The best way I've found to remove and contain this is to use a gel paint stripper and 4" wallpaper scraper (wear a mask anyway) but it should scrape up into a folding glob containing all of the harmful fibers. It will take several applications, but eventually you should have a clean WHITE slab. (If the black is visable you may, and probably will, have bonding problems even using an AMA with your thinset. It's tedious, messy, and stinky work, but not brain surgery.

After going through all of that, it would be a shame to not level out your floor, particularly since in comparison it's so easy. Custom's Building Products and others make self leveling underlayment, that you basically just pour down (after priming with acrylic latex in your case) and with a heavy notched trowel (3/4") even it up, and it'll smoothe out to a really nice surface to work on.

If you get that far and want some cool installation tips let me know. Please don't bother if you want to Micky Mouse it though.

 

Thanks guys! I know some of these tiles are already coming up, so there's hope for the rest. Any time I hear the phrase "Asbestos Abatement Firm," I think $$$$$. And it's $$$$$ which I don't have!

ljotile, there are a couple of issues with leveling, there is an interior (which I am assuming used to be *ex*terior) barbecue pit (not really a pit of course, more like a fireplace) and raising the floor significantly would lower the lintel; also an exterior, bearing wall door which would also have to be raised. Although I haven't mapped out the whole thing, I'm guesstimating as much as a 3/4" drop in places from one side of the area to the other.

However, we have recently thought of replacing that door with French style patio doors in an effort to bring much needed light into the den and since that entails basically moving the door anyway when putting in a larger header (doubled SYP 2x10 and jack studs for a 4' door. I like to over-engineer ) so maybe that's not an issue after all. Can you give me an idea of the price of the self-leveler you recommend?

NEWS FLASH! After putting on my trusty respirator (I work with toxic chemicals and am exposed to silica dust with my pottery so I have a most excellent mask) I went out to the den to see how well this stuff is stuck. Stuck a cat's foot under one edge (couldn't find my putty knife) and the thing popped right up! The mastic "bed" is spotty at best and maybe 1/16" thick. It's a wonder the stuff hasn't been coming up on its own. Not to say that it'll all be that easy of course.

 

Hey Cindy,

Cool you're going to do it right then.

Now if you have more time than money, (and it really doesn't take that much more time compared to considerable $ savings), you can use types S mortar ready mixed and bagged for about $3.00 a bag.

First thing to do. If you have access to a large building supplier purchase 1/4" foam strips used for glass block expansion joint material at headers, cut it into 1" strips and staple around the parimeter of area to be floated. (It's shear action that causes delamination from cutback (black glue)in the pores of the concrete. So we're creating an expansion joint at the walls to eliminate any sideways pressures from heat expansion or wall movement from slamming doors etc.. If you can't find the foam, or you're on a major budget use redwood lath and pull it before the mud sets by running a blade along it and pulling straight up with a back and forth sawing motion of the strip.

Now an eay way for you to get a consistant 3/4" is to use a piece of 1x2 firring strip at your low end to "rod" off of. Lay an 8' piece out and move it as you go.

So now lets say on your right you have the firring strip laying next to your expansion joint material and on your left the high section of floor. The distance between the two is my next question.

 

Sounds like you're in good hands, Cindy.

 

Cindy,

If your floor isn't a consistant 3/4" you can start off by "spotting" your floor. It's not that hard and will result in an almost perfectly flat and level floor.

Basically you'll put level spots of mortar from your high point in a grid 6' between . . . . after they set up you run a line about 2" wide to conect the dots. after the lines set up, you just fill in between them. (Your mortar bed should be applied over a thinset/acrylic latex spread to assure a permanent bond)

 

Thanks, ljotile! Sounds doable; persnickety, but doable and affordable. One of the reasons I had really hesitated to try leveling was that I ran across some sort of self-leveling compound at either Lowe's or HD, and the stuff was close to $30.00 for a not very large bag if I remember correctly. No further info, I'm afraid, I only remember being shocked at the price. $3.00 a bag sounds much better . The only other thing I could think of was putting in a "false" floor over top of all this stuff (the ceiling is 8.5') but couldn't think of any way to deal with the afore-mentioned lintel and door in that case. It will be some time before I get to the floor stage of the project what with everything else that has to be done (walls, doors, windows and such) but it's best to know now what will be involved so that I can plan around that portion if need be.

Thanks again!

 

Well, I've got to jump back in here. Sounds to me like we're talking about a convetional mud job over concrete. The "mud" will consists of sand and portland cement. You'll be better off buying sand and cement seperately.

John

 

Hi John,

I agree it would be cheaper, but more difficult and messy to transport, not to mention to mix without a mixer. Trying to put myself in her shoes, without a flatbed, mixer and crew. With a 1/2" drill and a paddle mixer I figure she can mix up a managable bucket at a time for spotting and chop up a wheelbarrel full to fill in between.

Also the added lime in the type S will accomodate feathering at the high end of her floor better than a deck mud. It will hold up better to foot traffic as well which might be a factor in that I doubt the installation is going to be acheved in the time a setter would do it.

The new threshold screw anchors should be drilled deep enough to be in the original slab by the way, rather than the new mortar bed, which will entail longer screws as well.

 

ljotile,, this is true. While I can transport the stuff in my trusty '72 pick-em-up, Orange Julius, moving it around, especially 90+ lb bags of portland is not my idea of fun. I was feeling a bit concerned over how strong the cement would be where applied thin. Thank you for answering my question before I asked it! Thanks also for the tip about the threshhold anchors. I might could've figured it out, but it's best to be reminded. I just love drilling in concrete ! Not. My 3/8 B&D is barely up to the task. For any drilling in this stuff I believe I will rent a 1/2" hammer drill.

Thanks again, guys. These forums are the best!