I purchased a house built in 1965 last year and the basement has leaked for the past 10-15 years on and off. As such, many of the floor tiles have become very loose and popped up off the floor. I know from neighbors that they are asbestos tiles (9x9) and since I have some ambition to renovate the 1500 sq. ft. basement, I have already started to remove some of the tiles. Because of this site, I learned and followed all the precautions discussed in previous posts to safely remove the tiles. It has gotten to the point that nearly none of the tiles break during removal.

My concern now, however, is what about the black mastic glue that is beneath the tiles. I would want to know if this is a problem as well. Someone informed me that I should cover the high traffic areas with plywood to prevent further disturbing any of the mastic that may contain asbestos as well. I was also told that as I remove the tiles, to cover the mastic asap with whatever new floor tile I decide upon. Any recommendations here?

Thanks!

You have three removal options with glue that is most likely to be asbestos:

1.) The Resilient FLoor Covering Institute (www.rfci.com) recommends wet scraping with water--soak it down and scrape using a scraper. Though recommended, I would find this very tedious and likely to leave lots of residue.

2.) Chemical remover. Floor covering people don't like these because the chemical agents tend to leach into the concrete and make future floor mastics less likely to bond. It would get the stuff off, however, it makes a really gooey and sticky sludge that will ruin just about everything it touches (including your tools).

3.) Leave it and skim coat it. I would not recommend plywood subflooring because of the possibility of moisture/condensenation and future mold. If you really want to encapsulate it, skim coat it with some sealer. Otherwise, just leave it alone. By the time you apply a new glue and floor, any fibers are most likely going to be "permanently" bonded in there and unable to get out.

Hope this helps.

Fortress Environmental Solutions
www.fortressusa.com

I think I’ll go with option 3 for now. Thanks for the info.

Could I use a concrete water sealer or interior latex paint for the skim coat? Would either of these cause a problem when I put down the new mastic?

Thanks.

From my standpoint as an asbestos-guy, you could use either. You would need to talk to a flooring-guy to see what he would say about adhesion of the new flooring.

Fortress Environmental Solutions
www.fortressusa.com

Hello,

I have almost the exact situation as the original poster. In house, built in 1962, I have removed the tile, and the floor is black mastic. I also have a persistent odor associated with the mastic that is unpleasant - in fact, I could smell it slightly before I removed the carpet, pad, and tile.

Skim coating sounds like a great idea, but I
am concerned if the odor will remain after a skim coat. Is it possible that it would?

Any suggestions would be appreciated.

Dave

I've never heard of the mastic itself smelling bad. I'm not saying it can't but this is new to me. Is it a petroleum type of smell or more sour? Asbestos itself has no odor at all so it would have to be in the binders--or in the floor beneath.

If it's a sour smell, I would be inclined to think there is a mold problem rather than the mastic. If that is the case, it's ultimately a moisture issue and the floor needs to be thoroughly dried before you skim coat it (e.g. humidifier for a few days until you don't have to empty it anymore). Also, if it's mold you'll have to address the reason for the moisture problem in the first place. But you probably know this already.

Sorry I can't help you more.

Fortress Environmental Solutions
www.fortressusa.com

Hello,

Thanks for your input.

The smell is hard to describe - there is some sort of pertoleum component, but it does have a sour odor also.

It looks like there has been some water issues in the room at some point in the past. Thankfully, there does not appear to be any water issue now. I think the smell is residual. I'm hoping that removing all the old material and drying the room out is going to help.

I very glad to know I don't have to try to get the mastic up and that I can seal it with paint.

Thanks again,

Dave

Since you have obvious moisture issues with the cement floor of your basement, coating the entirety with mastic will not work. Vapor and water will continue to "bubble up" via your concrete and "crack & pop" any mastic layer you attempt to "seal the floor" with - eventually!!!!

You'll end up with friable issues with the mastic all over again.

Best method is to:

Contract with a registered asbestos lab to test a sample of your mastic (they'll chip off a bit of your concrete surface containing mastic.

Even if the microscopic analysis is negative -- you'll need to be prepared for a more expensive BURN test. It is 80%+ likely you will have asbestos in the mastic.

The wet scraping method is your only reasonable approach in your already proven "wet issues" basement floor.

Keep in mind that until you correct for these issues any thing you do with this basement floor will most likely cause you other issues/problems (cracking, MOLD etc.). You really need to address your moisture problems before you think about throwing more finish money into the project!

The encapsulation method suggested by fort's post number 3 is obviously contra-indicated by the information the OP has already provided regards to his basement floor situation/conditions.

Its a nasty job -- but somebody needs to do it.

The odors you describe regards to the black mastic are common, especially when in an "always damp" situation, especially after having been recently disturbed by your removal of the tiles. Thinking it is also likely that at some point you either created friction during removal, and/or used the assistance of heat to help in your removal. BTW, this suggests that a slury of mineral spirits will be your likely most sucessful aid in its (mastic) removal. Also one coat of laytex paint is a class III moisture barrier.