Vinyl tile installation

[Ed62]

Our house is on a concrete slab. One of the rooms did have ceramic tile (I think) at one time, which is now covered with a large rug.

When I pull the rug back to expose the concrete, I'm finding what I expect to be the adhesive that was used for the long gone tile. There are "bumps of adhesive" all over the floor, and it is very hard. I tried with limited success to scrape those away, but many minor bumps remain. I'd rather not use a sander because of the mess it would create. In the past, I always thought that if I ran my hand over the surface to be covered with vinyl, and I was able to feel anything other than the floor to be covered, it needed to be taken care of before installing the vinyl.
But maybe the newer tiles are more forgiving?

The adjoining room has ceramic tile, just over .3 inches thick. The vinyl I'd like to use is .125. What would be the best way to handle this job? The difference in thickness can be compensated for with a transition strip, either bought or made.

Ed

[atgcpaul]

I laid cheap vinyl tiles in my first apartment and every little bump/speck of dust telegraphed through. Maybe more expensive tiles are stiffer, but you're still going to have lumps.

I would really try my best to scrape off that glue with one of those long scrapers with a super stiff blade. If that doesn't work out, could you put down some 1/4" plywood and then the tile on top? The bumps will still be there, but will be smoothed out over a larger area.

[wardprobst]

You may be able to rent a motorized floor scraper, it's not as messy as sanding but is pretty loud. I did our whole house with one and it worked out pretty well.
DP

[phrog]

I haven't tried it, but how about a scraper blade on an oscillating tool?

[Ed62]

Thanks for the replies. They're all appreciated.

I haven't tried it, but how about a scraper blade on an oscillating tool?

Aha! I have that tool, but it just never came to me to try it. Maybe tomorrow or the day after. I'll let you know how it works.

Ed

[gerti]

I wonder is a heat gun might help. Of course it could set the old glue on fire, no idea.

[mpc]

Yup, scraper blade on an oscillating tool. I used a file to sharpen the blade a bit when I had a similar job, worked well. Have a small water bucket handy though; when the blade gets hot the old glue will soften and gum up the works. And it's even harder to get off the blade once it sets up!

mpc

[phrog]

Yup, scraper blade on an oscillating tool. I used a file to sharpen the blade a bit when I had a similar job, worked well. Have a small water bucket handy though; when the blade gets hot the old glue will soften and gum up the works. And it's even harder to get off the blade once it sets up!

mpc

Buy a new blade.

[conwaygolfer]

There is a blade shaped like a triangle for removing the old thinset. It is made for the multipurpose tool. They work great at simply grinding down the old stuff. Have used it many times doing repair jobs.

Conwaygolfer

[Hellrazor]

You have to remove the imperfections and skim coat any divots, etc. Otherwise it will look ok for the first year or so but after that it will completely take the shape of any imperfections in the concrete floor.

[wardprobst]

I should mention that the motorized scraper is operated from a standing position and if you have much scraping to do is well worth renting. I've done it with an oscillating tool on my knees enough for this lifetime.
DP

[Hellrazor]

I have a vct project going at work and I am making them grind the old mastic off of 40,000 square feet of floors as part of the project. Essentially they are bring in a concrete polishing crew to remove everything and clean up the floors. It is around 70cents a square foot.

[capncarl]

Ed You are correct, every speck of debris left on the floor and ever irregularity will show through the thicker vinyl. Possible more visible after the flooring is down than the trash was originally.
capncarl

[phrog]

I have a vct project going at work and I am making them grind the old mastic off of 40,000 square feet of floors as part of the project. Essentially they are bring in a concrete polishing crew to remove everything and clean up the floors. It is around 70cents a square foot.

As Jethro Bodine would say, "Naught from naught is naught and carry a naught." 40000 x 0.7 and carry a naught and that equals a whole lot of money.

[jabe]

If the old adhesive is hard and firmly stuck on, U can use a self leveling cement base compound over it. Just mix it and pour it on your floor and it'll self level. After it dries install your new floor over it. HD sells it or any flooring store should have it. You can get more information & tips on youtube.