Background: 3,000 fl carbonized engineered bamboo installed Sept '08 on old and new concrete slab using Titebond 821. Bamboo left in garage (San Diego) to "acclimatize" for 3 weeks, but kept in original box. Floor cupping in multiple locations (e.g., master bedroom closet, hallway, part of family room/kitchen). Sample cut out of floor for analysis, by inspector (Titebond paid). Result, "cupping due to topical nature", not through the moisture barrier". Titebond's "independent" inspector reported wood moisture content varied between 7-14%. Two dehumidifiers running 24/7 for the past month, but no change in cupping patterns observed.

Questions:
1) I would like to obtain a second opinion from a truly independent floor inspector. Is there an association I can contact for names of inspector in my area? Is it worth the expense to get a second opinion?
2) Floor installer's resolution is to sand the entire floor. I'm a little worried about crowning not to mention the mess and disruption to the family. Are there other solutions to consider to reduce the cupping?
3) Contractor soaked the old concrete slab to facilitate the removal of old hardwood floor. Who's accountable if this is a cause of the problem? The Titebond analysis would indicate that the slab is not the source of the moisture and that their adhesive has created a good barrier between the slab and the wood.

Please help, this has been an ongoing, very frustrating experience for my wife and I.

try: http://www.woodfloors.org
This is the consumer side of the NWFA website. You may find some recommendations there on inspectors in your area (not sure)
Did I read you correctly that you acclimatized the floor to the garage conditions? Not too sure that was a great idea.
Also, it seems as though the floor is cupping only in specific areas. What is the common denominator for these areas in relation to the rest of the space?

yes, the boxes of flooring were stored in the garage by the contractor.
We've tried to identify the common denominator for the cupping areas, but are not able to come up with a plausible explanation. The areas are separate from each other, in different parts of the house. They are all on the old part of the concrete slab.

Thank you for the woodfloors.org link.

This maybe the common denominator. New concrete has a vapor barrier under it and the old slab does not. Just thinking out loud.

[quote="evorg"]
They are all on the old part of the concrete slab.


Thinking out loud myself... Is it possible old plumbing runs under the slab in the older section ?

Yes the plumbing runs under the slab (old and new (but new plumbing under the new concrete)). But the wood sample analyzed from the closet passed their adhesive barrier testing and they concluded that there's an adequate moisture barrier between the slab and the bamboo floor boards.

If the moisture is actually coming from air, how long does it take for the dehumidifiers to reverse the cupping? The dehumidifier in the bedroom closet has been running 24/7 for a month and there's been no change in the floor boards.

It's so tough without seeing the floor. Topical just doesnt make sense to me. Topical is usually uniform over the floor,(not just in areas, in the older area).

If I may throw a few thing around....

You mentioned the installers soaked the older slab to facilitate removal. I am assuming the removal was tile and thinset morter. I have heard of a few guys using this procedure for removal( the thinset is a bear to take up). But I would never use water on a slab getting a wood floor . Did the installers do moisture tests? Especially between wetting the slab, and laying the floor?

With that said...

I am not familiar with Titebond and their combination adhesive/barrier. But, the barriers that I install ( Bostik & Mapei ) claim to REDUCE moisture emissions.
I'm also not familiar exactly what the "testing" of the adhesive concludes , pertaining to the barrier portion of the adhesive. I would assume that it will conclude that it is intact as a barrier (ie. The installer used the correct notched trowell to result in an intacked barrier). But, I question if this particular test will tell the percentage of moisture that can , or is, possibly penetrating the barrier, since the barrier "reduces".

Or, as Gary said about the barrier under the older slab. It could still penetrate the Titebond.

Yes, I agree.

You have, isolated areas, that are random.

Our general contractor (house renovation) did use water to facilitate removal of the previous wood floors. I am not aware if the installers performed moisture tests. I don't think they were made aware the slab had been soaked to remove the previous floor. I wasn't even aware if this fact until I was informed by my neighbor who was told by the general when he was commenting to them on how hard it was to remove the wooden floors.

Do you experts think I have a systemic problem here?
What resolution avenues are available?
And what can we do about the cupping?

Well there are still a number of unanswered questions here.
How long between removal (and watering of concrete) of the old floor, and the installation of the new?
Are there no records at all of moisture testing?
There must be some link between the areas that are cupped. You should investigate that avenue completely before doing any corrective measures to the floor.
It may be that the floor will respond, but since you have been running dehumidifier(s) constantly for over a month with no change to the cupped appearance of these areas, there must be an on-going but concealed issue here.
Invest in a moisture metre (non-destructive) and take readings. Since there aree so many different species of bamboo being used, you wont get accurate readings. But what you will get, is comparative readings from area to area and day to day. Start a spreadsheet type log of the readings and read the same spots each time.

Thank you for those suggestions. I will look into buying a moisture meter and logging moisture readings from various areas. Any suggestions on modestly priced moisture meter brands you'd suggest to get my research started?

btw; the approximate time between slab soaking and new floor installation was probably about 2 months (July/August).
No there are no records of moisture testings. I will ask my floor installer if he did any tests and if so, how often and what were the readings (unlikely in my opinion that even if they were done there would be any records of the readings, but I'll ask).

Wagner Electronics make a variety of metres that will work for you. Since you wont need this on an on-going basis, I would recommend their L-609 as being adequate for the job. Again, I want to advise you that you wont be getting accurate readings; but that is not important. What you need in this case is comparative readings between the flat areas and the cupped areas, and any effect that the dehumidifier is having on the problem.

Wagner L-609 on order. Thank you.

First of all like the guys said....accliamation in garage is a big no no. Second no moisture testing another big no no see http://www.titebond.com/ProductLineTB.a ... prodcat=13

Next the soaking of the slab, could take months for the water to leave and be in an acceptable limit (under 3lbs) depending on the rh in the home and again, no moisture testing.

The adhesive manufacture will not take responsibility either way due to no moisture testing, period. Even though it sounds to me like there is more moisture coming through the slab than it can handle, keyword "mositure resistant" and it is not a mositure retarder per se. As they make a specific mositure retarder for that.

Plus, I bet the HVAC was not running at time of install (see link). The AC and or de-humidifiers are doing their job taking out moisture from the top, while the bottom is still wet. I doubt you will see the cupping go away any time soon.

I'd want a do over myself.

The OP says the cupping is only happening where the old concrete slab is. I suspect that that slab does not have a vapor barrier under it. It was not code for many years until more recently, late 80's/early 90's. The old slab is wicking up ground moisture. Either that, or there's a plumbing leak in that area. The concrete should have been tested, especially since bamboo was being laid.