Hello,
Can some one help me to straight out the "stability" question in general and on Cumaru (Brazilian Teak, Dipteryx Odorata) specifically. I've done extensive search on the net and came to completely opposite statements about Cumaru, some sides saying it less stable then red oak some - more stable.
On parent site of this forum http://www.hardwoodinstaller.com/hardwoodinstaller/species_brazteak.htm it stated that Cumaru is below average where red oak is average, and some other sites has same statements.
BUT
Here is what NWFA has:

Brazilian Teak
http://www.woodfloors.org/consumer/whyTypesSpeciesDetail.aspx?id=43
Dimensional Stability: Average (7.6; 12% more stable than red oak).

Red Oak
http://www.woodfloors.org/consumer/whyTypesSpeciesDetail.aspx?id=15
Dimensional Stability: Northern: average (8.6). Southern: below average (11.3; 31% less stable than Northern red oak)

for comparison Mohogony (Santos)
Dimensional Stability: Above average (6.2; 28% more stable than red oak).

and other sites has these:
Cumaru
Radial Shrinkage 5%
Tangential Shrinkage 7.6%
Volumetric Shrinkage 12%

Red Oak
Radial Shrinkage (G->OD) 4 %
Tangential Shrink. (G->OD) 8.6 %
Volumetric Shrink. (G->OD) 13 %
Average - Change Coefficient .00369
Northern: average (8.6)

and this as well:
http://www.woodbin.com/ref/wood/shrink_table.htm

Just logically thinking if wood has less shrinkage percent then that wood is more stable, so according to numbers cumaru is more stable then red oak.
I am sure i have some missing data/information that will complete the "stability" picture in my head and make Cumaru less stable then red oak but I can not figure it out what is it.
Just want to make one assumption: may be cumaru considered less stable then red because it's requires longer acclimatization then other wood and as a result more movement in the floor when it's installed in average acclimatization time?
Thank you in advance.

We worked with some cumara solid 2-1/4 a couple years back we did not install, owner installed. Wood was acclimated for about two months all reading on our meter read low 5% or less before install. The owner installed and finished the floor( they did an adequate job). First time the heat came on during next winter the entire floor gapped about dime sized cracks, There was no evidence of any severe changes in m/c or job site conditions. My thought is the exotics probably are not as stable around here as they are in the rain forests. We have looked at several different species and the majority of themn seem to be less stable than the domestics.

Thank you Mickey. Very interesting practical example. I am just curious, do you know if the owner had a humid meter in the house and if yes what was the reading at time of installation/acclimatization, what month it was installed and what state/city?

It helps to have more info. Moisture content of substrate/underlayment, time of year...dry season vs wet season. Need to humidify prior to install so in dry season it does not gap and all that . Five percent seems kinda low, like in my zone. I can hardly see wood gapping when the heat was turned on at 5% MC.

Sub floor was 5.5 -7m/c floor installed in Feb or March. Do not recall r/h but I am certain it was around 20%. I do not believe they ever installed a humidifier either. Was just glad that I was not the one who installed it. Gapping occurred the following heating season, could not find any evidence of excess moisture or humidity.

Very interesting, so all facts saying it should not shrink but it did. The only i can guess from my minimum to none hardwood floor experience that the owner did not shared some information and simply tried to blame the wood
I guess i don't want to play the "Russian roulette" any more with wood picking and going to install unfinished Rift or Q/R Northern Red Oak which always was my second/backup plan.
Now the question is: what type? Engineered or solid, i have no problem with engineered, don't have that mind "it's plastic" (even got samples from Owens - very impressed with quality). We leave in NJ where climate is not that stable. Thanks to this forum (learned a lot) i installed remote thermo/humid meter in every room (WS-9029U-IT-CBP - great device, installed two sensors outside on opposite sides of the house, synchronized all 4 stations with these two sensors and now can see temperature outside in every room as well ). Last two weeks was really bad here, outside humid was 80-90% but in the house it never went over 50% so for two months it's being 40 - 46%. Don't know how it will be in winter, but with forced air heating probably it will drop to 20% or even less. I do have plans to install humidifier but not sure that can do it before winter (some other more important plans). So knowing this two facts: Summer humid 45%, winter - 20% what type should i install: engineered or solid?

P.S.
Just want to share this link maybe some one find it useful
Wood Shrinkage Calculator
http://www.woodweb.com/cgi-bin/calculators/calc.pl?calculator=shrinkage

cumaru is pretty unstable in my book. I refuse to sell solid cumaru anymore due to the problems that followed every stinking job we sold. After the first problem we were very carefull on future jobs and still ended up with shrinkage. On the other hand we sold a 3k foot job last year after I refused to warranty and tried my best to change their minds that has been ok so far. The floor sat in the house for almost 3 months acclimating and it was glued and nailed down. Also has a high tech hvac that keeps rh in check. It can be done but too me is still too risky to promote. It took three months to drop 3 points in mc thats probally the biggest reason it fails, its hard to get that much acclimation time and not have people get ancy and want to go ahead and install before they should.

Thank you Kevin, you just nailed last nail into Cumaru casket, Red Oak it is. In reference to my previous post what type? Engineered or Solid?