Hi,

We are about to install engineering bamboo on a concrete slab using glueing down method. The installer removed old carpet and asbestos containing vinyl tile today, and scraped the asbestos containing mastic as much as possible.
But there are still stubborn black mastic on the slab. The installer said it is good enough to go ahead with the glue down installation, since the mastic appears stable and would have no negative effect on the utherane glue and
actually would act as a moisture vapor barrier. Should I believe him?

What are the reasons to remove mastic before installing hardwood products?
I understand that it is important to remove it for laying tile (because the uneveness would crack the tile easily), but I never really understand why it should be removed for installing hardwood (including bamboo).

I need some advice quickly so that I can stop the installer from installing the bamboo on top of mastic before it is too late.

Thanks for any advice.

Joanne

I would skim coat it with ARDEX SD-F. The ARDEX will bond and encapsulate the cutback adhesive residue, and the urethane bamboo adhesive will bond to the ARDEX, but the urethane adhesive could have bonding concerns with the cutback adhesive.

See what I'm saying.

I'm pretty sure he is going to have at least one high or low spot to fill, to make the substrate 1/8 inch in 6 feet, for flatness. Has he shown you the flatness of the substrate throughout the installation to show you it is ready to go?? Tell him to get out his 10 foot straight edge and show you the flatness, in both directions.

Thanks so much, Floorguy! I did insist that he show me the flatness using the straight edge, by reading past posts on this board. I learned so much from this board that it totally surprised the contractor - almost to an annoying point, since I'm asking questions all the time. Luckily he is a nice and patient guy.

Joanne

Another question. Where can I buy Ardex SD-F? Does any of the big-boxes sell it?
I looked on Ardex's website and couldn't find a distributor or dealer. I'm in Nor. California near San Jose (sillicon valley).

Joanne

SD-F would be a waste of money for that application. Better off using Feather Finish or Webcrete or Planipatch. Hell, you can find planipatch almost anywhere.

I'm confused. Isn't Ardex SD-F the feather finish?

No, chuck is confused. Yes, SD-F is the best feather finish I've used, and have cutback encapsulating in the specs.

Joanne,

You can buy Ardex Feather Finish at The Tom Duffy Company in Dublin, CA. That's just in little north of San Jose. There may be a location closer to you because I don't know where you live. Here's some links.

http://www.tomduffy.com/Branch_Location ... nJose.html
http://www.tomduffy.com/Branch_Location ... ublin.html
http://www.tomduffy.com/Products/Sundri ... dries.html

I'd call first to verify they have it in stock. How come your installer isn't handling this?

I guess they just changed the bag.

Gary,

Thanks for the tip on where to buy Ardex SD-F. I called the San Jose store and yes they have it. I'm buying this myself because my contract with the installer states that I'm responsible for all material, including bamboo, adhesive, baseboard etc. The installer is providing the labor including glueing down and installing baseboards.

However, the project is on hold as of now. The reason is that the calcium chloride test came in high numbers. We tested three spots in the kitchen/dining/family room area (all open to each other), one read is 12p per 1000 per 24 hours, the other two are around 9 and 7 respectively. I am somewhat surprised by the high numbers (this wasn't expected). I did the amature polyfilm test myself before and after three days, there was no visiable dampness on the film, so I thought the moisture level should be OK (the concrete is 50 years old). The installer wasn't planning on test because he said he had done the same installation in the neighbourhood in houses with exactly the same subfloor as mine and he never had any problems. He is willing to warrantee his work on my floor on both labor and material (meaning if anything goes wrong, he's going to pay to repair or replace the floor without me paying a penny). The installer is a friend of a friend's and seems honest and genuine.

I got nervous at last and insisted on a calcium chlroide test. Then the result scared me. I'm hesitant to go forward at this point. The problem is that I've already bought the bamboo and am not sure if I can return them (I have opened a few boxes to acclaimitze but the majority of them are still not opened).

From this board, I know that Bostik MVP may be used with Bostik Best to combat the mositure vapor from concrete. I'm wondering if I can still get the floor I dreamed by adding a Bostik MVP layer before the glue? - That'll increase my cost of course, but I'm willing to pay for it if it is going to work. Or should I simply give up on hardwood and maybe go with tile?

The other question is why one spot has such a higher reading than the others. Is it temporary that can be remedied? This spot is near the refrigerator and the ice maker leaked a couple of times during the past year (there was sheet vinyl in front of the refrigerator at the time of leak). Did this have any impact on the mositure level on this spot? Also my mom cooked a lot and there is usually some steam during cooking time in the kitchen, and that usually causes condensation on the glass walls surrounding the great room in winter. Would that affect the wood floor in any ways?

I now think that I was a little rush in deciding on the new flooring. Oh well, the important thing is what to do now?


Joanne

Get the newer MVP, they have out now.

Hi Floorguy,

Are you referring to MVP4? How is it different from MVP?

Joanne

The Bostiks web pages can explain it better then I can.

thanks out to Kirk Swenson for the information, it was very interesting. 908karolyn(holland)

First thing I would do is make sure your dealing with a licensed contractor. He can say he will warranty the work, but if he isn't licensed it won't hold up if it fails. There is a 500 dollar threshold in california for materials and labor, above that could be a fine and all that good stuff if caught without a license.