THE PLAN:
Install 800 sqft of 3/4" prefinished maple in a house that is not completely built yet. It gets A/C August 10th, I will run it until the install date of early September. We close on the house October 1. I will make sure with a hygrometer the subfloor is within 4% of the wood. The 3/4" T&G OSB subfloor is on the 1st floor and it has a full basement level underneath.

THE QUESTION:
The local wood supplier told me since the house is currently the wetest it will ever be, not to acclimate the wood before the install. He said he would only acclimate it on an existing house. Does this sound right?

If the interior relative humidity is high due to painting, tile work, green lumber, whatever, then bringing in a kiln dried floor at that time will only cause problems. Bring the flooring in when the relative humidity is stable at around 40 to 50 %. Sometimes, one needs to acclimate the flooring off site in an environment that will duplicate the home. BTW, maple is not that stable of a wood. I would shoot for no greater than 2% moisture content difference between subfloor and the flooring. So, in a way, your local supplier is correct.

A hygrometer is not the tool to use to measure subfloor moisture content. A hygrometer measures temperature & humidity. Use the numbers the hygrometer reads, to determine, what the woods moisture content should be, at that given hygrometer reading.
Your going to need a pin type wood moisture meter that is calibrated.

Gary is dead on... For an unstable species as Maple, you don't want the flooring to be no more the 2% difference in moisture content then the subfloor, or the Maple will gain or loose moisture and either buckle or gap serverly.


Your wood supplier is not educated about wood, especially a species as Maple. It is funny how these guys get jobs like that, and be so clueless about wood science.

My mistake, I will be using whatever the meter is called to measure the moisture in the wood. Guess it's not called a hygrometer.

I think I need to measure the floor after the A/C runs for a week or two to see exactly where I stand (acheiving 40-50% rh with the A/C running should not take long). If it is too wet, then I will wait. I'll try to go by the 2% difference you guys mention between the subfloor and flooring. What moisture content should the flooring itself have?

If I were in this situation I Would run the air for 30 days bring the wood in after the 30 then let it sit for a week prior to install take your readings and hopefully you will be ready to go.

I doubt the conditions where your flooring is currently being stored are consistant with your home, so to those who say acclamation is not a good idea I would have to disagree. Your flooring guy is partially right, it's not a good idea to acclamate to a wet enviroment if your house is not always going to stay that way.

Kevin

That is close to what I plan to do, run the A/C from Aug 10-Sept 10 then acclimate for at least a couple days.

If the subfloor is real wet I can use a dehumidifier too if needed.

The tool you need besides a hygrometer, because your going to need one of those too, is called a pin type wood moisture meter.


I would stick the subfloor the day before the AC is activated, to get a baseline starting point. Then after a week or two stick it again to see where it has changed(write these readings down, to document your findings, for later reference.

I would also stick the flooring, the day it is brought into the home for acclimation, to get a baseline starting point for it. Don't stack the cartons of flooring to acclimate.

What the moisture content of your flooring should be, is going to be determined by your hygrometer readings(temperature & humidity)

I think www.NOFMA.org has the conversion chart, used to figure MC at a certain Temp & rH


Acclimation is not a time thing at all, it is a moisture content thing. I have had to let wood acclimate for 2 months to bring it down to equilibrium. Had I installed it after a 2 week acclimation, I would have a homeowner screaming at me now for gaps all over their investment.