how clean does a concrete floor need to be?

[N8N]

...to put down tile?

reason I ask this question is I spent last weekend finishing scraping up the old tiles in my laundry room (I'd done the other half months ago; then finally I got sick of looking at the job half done and shoved everything to the other side of the room and finished it.) They were the semi-flexible kind, like you'd see in, say, an old basement, or a warehouse or something. I used floor stripper and a paint scraper and stiff scrub brush to get up "most" of the old adhesive, and it worked pretty well. Unfortunately I find that there was no edge to the tile where it enters the big room down there, it just continued on right underneath the threshold, so I can only assume that the whole basement was originally tiled, and then in the other room this nasty Berber carpet was laid over top of it.

The whole reason for this exercise is that the tiles in the laundry room were already starting to come up by themselves, so I assume that the ones in the main room are in similar condition, so it would probably not be a good idea to lay anything over top of them; they'd need to be removed. I think that long term we would like to pull up the carpet and then lay down new tile and use an area rug over top of it. Question is, if the concrete floor "looks" clean, but might have a few spots of glue here and there, is that clean enough to successfully lay down new tile, or does it really need to be eat-off- it spotless? If the latter, how does one accomplish that?

thanks,

Nate

[HeyBub]

The new tile needs to stick to something, else it will come up. Whether that "something" is bare concrete or dried glue that is virtually one with the underlying concrete is immaterial.

Assuming there are no "bumps" from the residual dried glue, your biggest enemy is dirt and dust. Glue won't stick to dirt worth beans.

So, if the former glue is really, really bonded to the floor, you can put tile on top.

[hallerb]

you can rent a floor cleaner polisher and use abrasive pad to wear away and smooth the surface.

basements do better with tile and area rugs, in case water gets in somehow

[DerbyDad03]

re: Glue won't stick to dirt worth beans

Actually, glue sticks to dirt very, very well. That's why it doesn't stick to whatever it is you want it to stick too.

[DerbyDad03]

re: I assume that the ones in the main room are in similar condition

That may not be the case. If the laundry floor got wet more than a few times over the years, that might explain why the tiles are coming up.

You might not have that problem in the main room.

[N8N]

You're right, of course, but I can't count on that. also the tile was painted over (!?!?!?!) seriously, it was this old school white stuff with gold flecks and someone painted right over top of it with blue- grey paint. Looked really awful. So I can't make any assumptions about the main room one way or another unless/until the carpet comes up, and I have to assume worst case, that I'll have to scrape and scrub there as well - because I'm sure that if tiling over old tile is half assed, then tiling over old tile that's been painted is quarter assed at best. I do have *some* standards :)

nate

[KLS]

This doesn't apply to you as you've gone past the point of no return: I just wanted to post my wonderful, albeit ugly, experience with those great big 24x24 soft foam interlocking pieces that are supposed to be used for kids. A neighbor was throwing out a set, and I rescued them and put them on my laundry room floor. Joy! A soft comfortable floor surface to stand on that's not slippery and doesn't care about water!

[N8N]

Actually i've seen those at Harbor Freight and thought about picking some up. I wouldn't say "point of no return" - the nasty old tile needed to go anyway. I now have a nice-ish bare concrete floor, which is way better than what I started with, or I can go all out and cover it with something if I choose to make more work for myself.

At least I can *clean* the floor now, as opposed to before, where you'd just push the dirt around into the spaces between the tiles. And you could never tell if you had a water leak until it was serious, and if you saw water, you could never tell where it was coming from because it'd run underneath the tiles to the low spot and bubble up there. (that was really the main impetus behind this... the previous owners "never had any water in the basement" but I seem to have found tons of little drippy things to fix.)

nate

[HeyBub]

Right. Thanks for the correction.

[KLS]

Then you should get a set. It's easy to sweep up stuff off of these things. I haven't tried wet mopping yet as I haven't had any wet messes to clean up, but I'm pleased with how much better these things make life down in the basement laundry room. Amazing what a difference standing on these is from standing on concrete (mine are on a somewhat uneven concrete floor, too, and they're very forgiving of the less-than-perfect surface). Wonder what color the HF ones are. Ours are the primary colors: red, yellow, blue, plus green. Pretty!

[N8N]

HF's were dark grey, and they were sold as work mats for standing in front of a workbench/machine tool/ whatever. Only thing I wonder about those is the suitability of using them close to gas fired appliances. They were also fairly thick IIRC, so I guess I would probably just lay them down in the middle of the room almost like a rug, and not try to go under the sink, washer, dryer, etc.

nate

[KLS]

Our dryer is gas, no problems whatsoever. I've laid these mats in the center of the room as there's really no point in going underneath the washer, dryer, or sink. I'm sure HF's are cheap, but I bet you can get the bright colored ones at Big Lots or BJ's, that kind of place. Those might be thinner than the HF ones and perfectly fine.