Concrete over old asbestos tile... - Contractor Talk - Professional Construction and Remodeling Forum

Cellomangler · 10-19-2007, 10:14 AM

Shouldn't 2 inches of concrete be sufficient to encapsulate an old asbestos tile floor ?
And I have these additional questions:
- Would I still need to glue down or remove the easily removable old tile?
- Where there is old carpet and linoleum glued on top of the old asbestos tile -I can rip that up, but do I need to worry about the old mastic left on top of the tile ?
- Any preparation of the old service - just a good mopping ?
- Should I make sure the concrete is of any particular mix to insure a smooth and stainable surface ?

Cook · 10-19-2007, 01:49 PM

If there are loose tiles now you can expect even more tiles popping when you remove the old linoleum and the carpet if glued down. If it is put down with strip and pad the tiles on the edges will most likely go as well.

Encapsulate an old asbestos:
Asbestos should not be disturbed.....take up and re glue down is considered disturbing the material.
2 inches of concrete is more than enough,but if the tiles are loose under neath it ,a new problem is being created.

Bet it is cheaper to hire someone who is licensed to remove all the old flooring
and get a start fresh.

Most bigger shops have a Demo team. Quicker and less expensive than pouring a 2 inch cap. A good demo team can have 1000 feet up and gone in an hour.

To do a good cap the surface needs to be bead blasted (roughened up)
then a primer put down . Cant do that over a tile floor.

Wait ...you were looking for answers not more things to think about...sorry

Cellomangler · 10-19-2007, 02:29 PM

A demo-lition team ? I wonder what kind of costs I'm looking at to properly lose the old asbestos tile and mastic ? I'm on a really tight budget, unfortunately, but yet I want to do something attractive in the end. So a demo team would sandblast ? That would be OK, considering there's nothing in there to be damaged -cinder block walls, old rough-sewn 2x12 25' joists. All the walls can go as well as toilets. I'm in Iuka, MS, so I'd have to find some sources for that trade.
I've just heard horror stories about the cost of removing asbestos tile by the pros... Answers always do come with more questions -like zooming in on a Mandelbrot fractal.. (I'm into computer graphics..)

Floordude · 10-19-2007, 04:10 PM

Once you get the asbestos tiles removed, you will be left with a real big bond breaker. The black "cutback" asbestos adhesive. I hope your not thinking of bead blasting that and creating dust. It has more asbestos, then the tiles.

Cellomangler · 10-19-2007, 05:18 PM

OK Floor Dude... don't leave it there... what is it that you would recommend?
I've been going over every idea from re-gluing some of the loose pieces of tile, applying leveler, then 1/4" plywood, then ceramic tile or vinyl sheets....
Just seemed like the concrete would be quick and allow for a lot of custom stain patterns for the most buck... Like I said, it's 2000 sq ft and I can remove any/all walls -probably will anyway because there's some rot in some stringers due to old leaks and I'm redoing the electrical & plumbing.

Cellomangler · 10-19-2007, 05:35 PM

One thing I don't understand (besides the grand unification theory) is why 2 inches of concrete would have trouble bonding or why it would even need to worry about bonding ? If the old asbestos is forced to lay flat so that in no way will it end up sticking up through the concrete, then how is 2" of 'crete going to slide or lift up or even need to worry about a marriage with what's underneath ? Ain't it just gonna squash it ? Is there a primer to put on first before the concrete that would help do the trick ? And what about that type of concrete ? I know I'm asking for a lot of free help but I sure couldn't find answers anywhere on the web... and I've been to the end of the internet and back...!

Cook · 10-19-2007, 06:21 PM

This was done by another company. I got the job of fixing it.$$$$$
Look at the back wall. It was 3.5 inches thick. It popped.

A search on Google....Remove floor tile that has asbestos in it ... should save you some money.
Added a pic of the cap.. hope it come through.

Cellomangler · 10-19-2007, 08:38 PM

All I see is the rubble and it only looks about a half inch thick. The back wall looks like where the baseboard was glued. The depth of the pieces and the markings on the right side wall are not 3 inches. I'm not calling you a fibber, I'm just not sure what you are trying to show me here. The photo doesn't tell me why it "popped" and why it would ever pop in my situation. I'm not going to be using heavy equipment over it -this is for a studio/residence. Can you give me any more specifics on what problems would arise with my scenario and why? Thanks for any and all feedback...

Cook · 10-19-2007, 10:05 PM

Well if the pic was at the beginning of the job you would see 3.5 chunks.
What you are seeing is where they tapered it off to a feather edge.
Picture was for the owners question as to why the floor was crunchy.

It is your job and your buck being spent.

Reason it popped is the two slabs expanded and contracted at different rates depending on their density and the temperature. There was also no bonding agent used .

On your project ...

I see a slab of concrete expanding and contracting at one rate. Fine.

VAT on this slab expanding and contracting at a different rate.
The adhesives (like a rubber band) allows it to do so without popping off the floor. Fine

Now lets add another slab on top of the tile with a questionable bond and yet a third expansion and contraction rate. It will stick for a time. It will stick until there is change in temperature. I honestly don't know of a primer for concrete to VAT (vinyl asbestos tile) that works.

I think the first thing to do is see how the old tile comes up. It could come up clean leaving little or no adhesive on the slab and unfried.

Well again it is your time and money.

Stained concrete is making a big comeback so I hope this all works out for you.

CaliDesigns · 10-20-2007, 12:56 AM

Pour your cap with a bond breaker. You don't want it to bond. Let it move independently from the other floor, including perimeter expansion jt. I would recommend 3" think concrete, 1/2" max aggregate, .45 water/cement ratio, utilizing a mid-range water reducer for workability, #3 rebar 2' on center, 6 1/2 sack mix to maximize the acid stains. I've even incorporated 1/2" tubing for radiant heating. From what I understand, you are not pouring on a slab on grade. Keep in mind that if you pour a 2000sq.ft slab 3" thick, you will be adding 68,000 lbs to your floor. I've done it on third story wood structured floors before, just had to sister the joists. Understand your loads. Good luck with your project.

Cellomangler · 10-20-2007, 04:52 PM

The local concrete maestro -I just met with today- also suggested 3 inches. Since I'm eliminating all the interior walls prior to the pour (none are load bearing) he recommends cutting an expansion joint where the walls will go after the fact. As far as the mix and rebar is concerned, none of that was addressed, but I do want to make sure that I use a mix that will stain properly and find out if reinforcing is necessary. What type of bondbreaker do you recommend ? He also recommends pouring very soon before it gets into cold weather... Thanks a bunch..