Help!
Scenario: A 50-year old medical facilitys concrete basement slab has two and three layers of resilient floor coverings (VAT, VCT, and sheet flooring) with high moisture readings. The hazmat reports indicate asbestos in some selected areas in mastics and in the VAT. The owner does not have the resources for a complete removal of the existing coverings down to the existing concrete. We have yet to find any coating that can be applied to the resilient substrate with adhesion and moisture resistance properties and also be acceptable to the new floor covering mfrs (also resilient) adhesion requirements. We have also searched for floating membranes which does not have adhesion properties to the existing resilient substrate but will provide an adequate substrate for any new floor coverings with limited results.
Any suggestions or recommendations will be greatly appreciated.
I admit to knowing little about asbestos abatement, but this seems strange and I wonder if further investigation is warranted. If the VAT is the bottom layer, how is asbestos abrading and migrating to surface or into atmosphere?
You are correct, Michael, the asbestos materials is not the problem. The floor covering product mfrs are scared of the high-moisture readings. The standard moisture test is to core down into the slab. I was told they never test the surface which has been dry for at least 20-years; which makes sense, because there are at least two non-porous layers of resilient floor coverings over the slab.
If there is still high moisture in the flooring system after 50 years of building occupancy it is likely that moisture is coming through the slab from the soil below and that there is no vapor retarder below the slab. This moisture needs to be controlled, which may be possible using a moisture mitigation membrane applied to the top surface of the slab, but it seems unlikely that the membrane manufacturer will warrant an installation over other materials. The best course would be to contact manufacturers such as Koester to see what they recommend for substrate preparation.
Ron, does top of finished floor affect anything important like floor-to-ceiling heights, door bottom clearance, etc.? How important is the warranty?
This doesn’t sound like occupiable space unless some real work is done (can you say encapsulate with underlayment or topping slab?
There’s a snowball’s chance that Jeff Mosely at Sinak might be able to pull something out of his magic bag of tricks. I can’t imagine what, but they have some interesting products.
BTW, how did they core or test the slab without encountering the asbestos?
Greta: Would you please expand on the product or full name of Koester. My search on Google and 4specs.com didnt find what I thought was the right fit. Thanks.
Regarding your comment about no vapor retarder below the slab raises an interesting off-topic question. Obviously we dont know for sure but we can assume there may not have been one during the original construction. As I recall we used 6-mil Visqueen a low-density polyethylene plastic sheeting under concrete slabs back then. So it would be interesting to find out the life expectancy of that old product. My guess is that it has been gone for a long time now.
Ken: I will check out Sinak, thanks. The membrane we are hoping to find will be in the 20- to 50-mil range, moisture-resistant, should act as an encapsulator, and be acceptable to the new floor coverings mfr’s requirements.
Ken: What asbestos? Da Boss didnt say nutin’ about asbestos.
Koster great products, too expensive for my clients
Koster is good as are Aquafin, Ardex, Custom Building Procts, Mapei, Sinak, and others; I’d be curious how they would look at doing this considering they typically apply direct to deck.
Jeff’s contact info:
Jeffrey T. Mosley
Technical Representative
SINAK Corporation
4901 Morena Blvd. Suite 601
San Diego, CA. 92117
1-800-523-3147
Fax: 1-619-295-0227
Cell: 1-661-428-1211
jeff@sinakcorp.com
Sinak’s founder, Craig Higgins, has developed a wide range of solutions to a variety of issues. No telling what he has lying around that might work for you.
My concern would be that if there’s already a moisture problem, just adding another layer of finish without stripping all the way to the slab first will still get bubbling or cracking. A fairly thick reinforced cementitious topping might solve this, but, as Ken noted, adding more than a thin coating might create problems with clearances, etc.