I was the general contractor for my home located in south eastern PA. Aside from the bathrooms, the flooring on the first floor is all 200 year old resawn/reclaimed wood from local barns made of 3",4", and 5" oak. The wood was piled in the house in April and acclamated for about one week. For about 3 days after the floor was installed, the A/C was not on and the inside was hot and humid.

Three weeks after installation, the floor started to cup - at first it wasn't too bad and I was hoping that with dryer/cooler conditions the floor would return to normal. Instead it got significantly worse. I had hired another installer to apply the final coat of poly but he refused the work since the light sanding job could rip the high part of the wood. He said that the floor was likely installed improperly not allowing for exapnsion spaces nor the 1/4" space under the baseboard. He suggested that while cupping is caused by moisture, he did not see any evidence that such cupping was the result of what he described as fairly normal conditions. There are no leaks in the basement and it had been 9 months from the time the concrete walls were poured and the floor installed. The original contractor who hired an outside installer came twice to look at the floor. The initial moisture reading which occured around labor daw was 61% with 14 reading in the wood. This was after it had rained 4 days straight. I bought a de-humidified and a moisture reader. The moisture levels were higher inside when it rained. The flooring contractor suggested to wait one month and see if the dryer air would reduce the cupping and pushing. I told him a week later this was unacceptable so he came again with his equipment. This time the moisture level was lower about 56%. It rained later that day.

They hired an independent inspector. His report did not put fault on anyone but did say that if the floor was installed improperly the wood was buckle and not cup. To me I would think a floor would need to cup and then buckle. The second installer came back resanded and finished the floor. It looks tons better! When he removed the shoe molding, you could see the line where the wood was pushing against the wall.

I believe (as does the second installer) that there were no expansion space placed (there aren't any in the second floor hallway -suggesting there may not have been any on the first) and not enough space was allowed under the shoe molding. If the inspector is right than I question if the installer should have layed the floor down at all because moisture was too high or the subfloor too humid and is liable from a lack of professionalism standpoint. I offered to split the cost in half but was refused. Only option is to go to small claims court.
As the general contractor for my own home am I at fault or is the installer at fault for a poor job? Thanks

Unless otherwise noted, a subcontractor is responsible for the work he performs. He may not be responsible for the performance of the material if he did not supply the material. The installer/subcontractor is responsible for testing the product and checking the environment to ensure a successful installation. If the installer requested that you, as the general contractor, have the HVAC up and operational and you did not do it, then he should have not laid the floor OR obtained a release of liabilty/waiver from you.

I think, under the circumstances, this is a fair compromise. The only thing I would have added was you should have allowed the first contractor the opportunity to make the repairs. By hiring the work out to another, you may have voided the first contractor's liability. I'm no attorney so either speak with one or go the small claims route and let a judge decide. And BTW, you're meter #'s don't make sense.

Is that 61% a relative humidity reading and the 14% a moisture content reading? Both are TOO high unless you live in the swamps of Louisiana.

WRONG. Wood cups from absorbing more moisture on one side than another. Cupping is very common. It usually occurs when a subfloor, or the space below a subfloor, is at a higher moisture content than the wood. NOFMA recommends there should not be greater than 2% between plank flooring and subfloor MC. Cupping can occur over basements, crawl spaces, concrete slabs with engineered flooring, etc. Moisture testing is imperative to ensure a successful installation. Expansion space, while required, is not the CAUSE of cupping. It will not remedy it either. Excessive moisture is ALWAY the cause of cupping. Basically, in your case, the flooring was improperly acclimated (because no HVAC was on) and it does not appear any pre-installation moisture testing was done, as typically required for a successful installation.

What does this apply to,
"Excessive moisture is usually indicated when the average moisture content of the underfloor materials (checked in several places) is more than 4% higher than the average expected EMC (equilibrium moisture content) for the area."
http://www.nofma.org/CertificationGrading/ComplaintsandComplaintInspections/NOFMAFAQsGeneral/FAQsProblems/tabid/117/ItemId/25/Default.aspx

4% for strip flooring and 2% for plank and dimensionally unstable spiecies in strip flooring, like Maple and BC.

What dimension is considered a plank,my new floor to install is 3 1/4"?

So taking a moisture reading of the subfloor by itself is not appropriate. The installer recorded a MC of 16 in the morning and a few hours later told me that the MC had reduced to an acceptable level.
Two thoughts:
1) How is it possible to have the MC reduce that dramatically in the span over a few hours?
2) The hardwood is very old barn beams that the second installer described as brittle. It absorbed a great deal of stain due to its dryness.
It is likely that this wood has a lower MC than other hardwoods. I am thinking that even if the subfloor was able to get to an acceptable level for standard hardwood, it may not have been low enough for this wood.

Good question!
According to NOFMA, strip sizes are 1&1/2", 2&1/4" and 3&1/4". This is for 3/4" thick flooring. And it refers to UNFINISHED flooring. Plus the strip sizes for other thicknesses such as 5/16", 3/8" and 1/2". NOFMA says plank sizes start at 4" (for 3/4" flooring) and go up from there, usually in 1" increments.
So, you're 3&1/4" flooring could be considered plank or strip, depending on whether it is unfinished or prefinished. Also, plank graded flooring is typically longer in lengths than strip flooring. Prefinished manufacturers typically consider 3&1/4" flooring to be plank flooring.
http://www.nofma.org/Portals/0/Publicat ... Floors.pdf
See pg. 6
One further note. In this NOFMA nailing guide, it says plank sizes start at 4". However, I've installed many floors that were random width plank that included 3" widths and those 3" boards were sold as planks by NOFMA mills and by the distributor.

Answer.
1) Doubtful that it did. If you did not see the measurement, then how do you know? Are you relying on what someone told you? If a subfloor measured 16% moisture content in the AM then a lot less, later on, say 2PM same day, then the meter was off or the person was using it incorrectly.
2)Typically, hardwood flooring is kiln dried down to quite a low MC. Then moisture is re-introduced to bring the flooring up to the norm of the area in which it is to be used. In most parts of the US and Canada, the AVERAGE MC at end of manufacture is between 6 and 8%. It should be a little higher for the gulf states and areas of higher humidity year round. If your flooring was milled by a local mill, they may not have "conditioned" it to the area properly and sent it out with a very low MC. That is why ACCURATE moisture content readings are to be taken of the flooring and the subflooring PRIOR to installation. And in your case, prolonged acclimation would have probably allowed the flooring to achieve an equilibrium with the environment and subfloors. But that didn't happen. Seen it many times. Kiln dried flooring brought into a damp house, no heat, high MC of subfloors, little to no acclimation, floors immediately installed and the result? A month later, the floors are cupped big time. Has nothing to do with expansion spacing. The equation is simply this. Dry flooring+ damp subfloors+no heat= failed floors.

3" width are planks. I don't understand Gary's post.

Specifically, what don't you understand? If you click on the NOFMA link, it will take you to a page in the NOFMA installation manuel that specifies nailing schedules. On that specification page, NOFMA states planks are 4" or wider.
And that 3&1/4" flooring is considered "strip" flooring. However, I do know that many manufacturers of PREFINISHED 3&1/4" flooring call it "plank" to differenciate it from their 2&1/4" "strip" flooring. Bruce does this, as does Hartco and many others. So, personally, I think as you do, that anything 3" or wider is really plank flooring, regardless of whether it is prefinished or unfinished, and nail it accordingly.