Hi to all! Great forum here! I'm a new homeowner with a 1950-era cape cod. Am getting ready to have 3/4" reclaimed white oak floors installed in a recent addition to the house, which is about 12-1/2 x 17-1/2'. The room is on a crawl space with a cement floor (maybe 3' clearance.) I pulled out the carpet and base molding already. The subfloor looks like 3/4" plywood on 16" joists. There are a couple of water stained areas on the subfloor--looks like windows were left open and that there was a roof/gutter leak that has since been repaired. I think the plywood is still solid, but am having my installer take a look.

I'm in VA, where it can be extremely humid over the summer, and my house is in an area with a high water table. (I've got a sump pump in the crawl space under the main part of the house, but I've never seen water in the crawl space under the proposed hwf installation.)

This is my first time with these installers and my first time having wood floors installed in general. So my concerns are: It's late January now, and dry. What should I do to help insure that I have no problems later with wood swelling and cupping? Do I insist that they take moisture readings? (They didn't think this was necessary.) Ask for a week+ acclimatization time? (They thought a couple of days would be enough.) What would be the best material to put between the subfloor and the hwf? A flooring company recommended Aquabar to me--any thoughts on this?

I hate micro-managing contractors (especially when all I know about flooring is what I read) but after reading all the posts about humidity/cupping problems, I want to try to make sure it's done right the first time. Any advice on how to manage this would very appreciated!

Acclimation is not really a time thing, you can acclimate wood for a month, but if the house isn't where it should be it is just a waste of time

the hardwood and subfloor moisture content should be within 2% of each other, you will need a moisture meter to check this

The relative humidity inside your home is a big factor, you can have the wood installed with the MC being within 2% of each other, but if the R/H in your home is 20% now (because it is winter and you're running the heat) then this summer when the humility comes and the inside of your house reaches 50% that's quite a swing, and the wood will grow, then when winter comes next year you will have gaps

You need to find what the average R/H for your area is (ours in Illinois is 20 in winter, 60 in summer) if we run the ac during the summer we can get it down close to 40%, with a dehumidifier running we can get to 40% as well, if both are running we can get around 30-35 in the summer.
If we run the humidifier during the winter we can go from 20% to 40ish (once we get around 45% in the winter the windows fog up, so I have people keep it close to 38-40% in the winter)

I would suggest getting a hygrometer (it measures R/H) they aren't expensive, I would check the R/H in the room, find the average R/H for your area, then get a humidifier (because its winter now) and get the R/H up in the room to the average for your area, wait a couple weeks, then have the wood delivered and wait for it to acclimate.
Have it installed, then this summer run the AC/dehumidifier and keep it close to the R/H that you had it installed at, and viola your floor will never move.

my house is from the 50s, over a crawl space, subfloor is 1x6's where i can see the dirt below through the cracks in the boards. I installed 6mil plastic in the crawl space, taped to the foundation, used 15# roofing felt as underlayment for the flooring, have 2 large humidifiers inside during the winter, and 2 dehumidifiers in the crawl space and one more inside during the summer. They aren't the best looking things, but they have allowed me to keep my R/H within 5% year round even with the windows open, best of all my floor doesn't move enough for me to notice

Thanks for your reply--lots of good info. I took your advice and purchased some temp & rH meters, and also an inexpensive wood moisture meter. (Lets hope it works.)

You know, I can't help but wonder... people have been building homes with hard wood floors for centuries, before there were vapor barriers, humidifiers, dehumidifiers, or central air... How did they manage it? Did they just space the boards for the highest humidity expected and live with gaps between boards in the winter?

I'm assuming that the installers today should place the boards snugly together, regardless of the season/temp/humidity? You never space boards closer or further apart to counteract humidity changes?

Does the fact that the wood to be installed in my house is reclaimed make a difference? Would 60+ year old oak be more dimensionally stable than newly purchased wood?

Thanks!

older wood is more stable IMO the floors that we refinish that were installed in the late 1800s and early 1900s were installed before things like central air, they preformed well, but they also have 3/8th gaps between every board now.

Sometime on winter installs people will install washer rows, where every x amount of rows they will install a row with a gap in it, some people use washers, some use fishing line. This method works if you calculate how much the wood will move correctly. If you don't some of the gaps you left for movement may never close up. It is much better to adjust the r/h and keep it constant, plus its actually more comfortable during the winter if your house isn't super dry