Your observation is correct. The reason is because you want the finish floor and the subfloor you're fastening it to to have roughly the same moisture content so they'll expand/shrink together. The expansion/contraction may be tiny... less than 1/4" over a large room... but it's powerful enough to loosen nails and split the tongues.
That's also why the finish floor should be acclimatized in the same room, or at least the same level of the house, where it will be laid.
Good thinking. Unfortunately, during my house renovation I've got too many war stories about buying cheap and paying for it heavily at the other end.
The worst was a Jacuzzi I bought online and tile I got cheap at a contractors' salvage yard. That story is here:
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And just to demonstrate that I don't learn from my own lessons, another one was just yesterday. I needed some wallpaper to finish off the guest room I'm building. I spent an afternoon hitting local wallcovering stores and the Borgs looking for something I liked which was also in stock. Nothing. I found a yellow pages ad for a store in Boro Park which claimed to have a million rolls in stock. As soon as I walked in the funky place, warning bells should have gone off. There were disorganized boxes of wallpaper all over, none of it with so much as a manufacturer's label. There was also a large pool of water on the floor in back from a leaky roof. The owner said it always happens after a heavy rain.
After an hour, I found some prepasted stuff which was acceptable, feeling victorious about saving $5 over what I would have paid elsewhere. I hung it last night.
This morning, it was curling up and falling off the wall. It's not like I haven't successfully hung a lot of wallpaper in my life. This stuff was damaged goods. I tested a piece and found that the paste was almost useless. In a side light you could see where some of it was dusting off. Then I thought about that pool of water and what the recurring humidity may have done to it.
One of these days I'll learn the wisdom of "Cry Once", I hope.
Not so. There's no way that a plywood subfloor is going to expand and contract like solid wood. The wood strip floor slides on top of the subfloor.
This site has very complete information on the effect of moisture, strip size, way the wood was cut, etc.
The rest of the house and the subfloor should shrink and expand at the same rate as the wood floor. That is why you acclimate the wood flooring before you install it. If everything expands and contracts at the same rate, you should not have any problems.
Everything expands and contracts at different rates, both based on temperature and on humidity. The same species of wood can have markedly different coefficients of expansion depending on whether the wood was flat or quarter sawn.
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The plywood subfloor and finish flooring will not react to the changes in humidity in the same way at all. That's one of the major benefits of plywood - the cross grain limits the expansion and contraction.
R
Plywood is cross grain for each layer it wont contract-expand the same as plank, plank length will not shrink it is the width that shrinks . Floor instalers need a moisture meter to check the condition of the floor to the home as storage -shipping is where it will meet high humidity or wet conditions. It is also a matter of it being the proper moisture for a closed house during new construction and what it will be when heated and cooled. Without a moisture meter and tables it is a guess likely to fail.
I have a similar story to tell. I have had shoulder pain for the last couple of weeks. A few trips to a massage therapist didn't improve the situation much.
One day I finally realized what was wrong with my shoulders. I've been painting my whole house in anticipation of new hardwood and carpet. My shoulder pain was the direct result of me hand sanding the walls.
I had though about buying a $20 sander but thought I could save the $20 by hand sanding.
So I finally broke down and bought a $20 electrical sander and the paint job went much faster and the shoulder pain disappeared.
Even though my insurance covered my $200 massages but I still had to endure the pain and suffering for a few weeks.
If you've got a long-running house renovation in progress, it probably won't be the first time you'll visit shoulder pain. I had it for months after building a pair of fences in 2001:
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Even though I used a framing nailer, the gun's still quite heavy. After driving several thousand nails the kickback gets to you, plus digging a few dozen post holes by hand didn't help. Fortunately, the neighbor who got the second fence is a chiropractor.
I re-injured it last year after tripping over one of those BigBoxStore toilet paper packages in my shop and landing on the cement floor. That stopped work cold for six weeks.
Yeah, that'll kill your shoulder, especially sanding ceilings. I still prefer to do this mostly by hand with a sanding block because of the dust that a power sander kicks up. What makes it worse is that my walls are old, neglected plaster so I elected to skim coat many of them after patching the cracks/holes. The finish work for that generates an unbelievable amount of dust.
My local rental place has a power sander coupled to a shopvac-like device but I've never tried it.
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