Thanks for taking the time to read my question.

We just moved into our 1st house this July. It was built in 1971, 2 1/4 white oak flooring throughout except for foyer and kitchen. Hated the tile so replaced with common #1 white oak and refinish the rest of floors while we were at it with 1 coat of bona traffic and 2 coats bona demo. For a 50 year old 2 story house it had some cracks between the boards but I thought overall it was great for the age. It's now winter in the north east and I noticed we are getting quite a few new 1/8 gaps in the original floors. Some hairline in the new section. I thought for sure given the age of the floors any shrinkage would have occurred by now. I work in work working so I'm familiar with wood movment but flooring and seasonal changes is sonsomething different. Can someone me understand why many more gaps are appearing? And is there anything I can do?

Some addition info if it helps:
Basement is unfinished,
Seems like it's worse on the 1st floor.
Don't have a humidity meter but will get one.

Thanks, merry Christmas

SL

the wood will expand and contract with each season as the humidity changes. your best bet is to run a humidifier during the dry winter months and try to maintain a consistent humidity reading throughout the year.

The boards will continue to expand this much after 50 years? Before we refinished the floors in the summer it looked pretty good for the age.

Did we do something wrong or not do something we should've when refinish the floors that would cause the this many more gaps to appear?

Yes. Listen to Jeff.
Age of wood does not matter.
Most likely it was more humid when the floor was tight. Now the Rh is lower.

Thanks for both responses.

They were refinished in summer, so I guess humidity at install time is key. That being summer was probably peak.

I take it that even though the floors were literally unfinished for 1 weekend they could absorb moisture really fast?

Will the gaps get smaller after winter?

Any suggestions other that filler for the large 1/8 gaps?

Thanks
SL

It would have been nice to have the moisture content when installed. Not all flooring gets installed after being in a climate controlled warehouse after being delivered to a distributor. This will affect the quality of the installation. Slack times will mean more time for changes in moisture content between when the flooring is delivered from the mill and then later installation. A gap of even close to an eighth inch for two and a quarter width strips mean a very large change in moisture content which can sometimes occur, but would be unacceptable in a kitchen. The mechanic needs to install with moisture content in a mid range between moist and dry seasons to mitigate cupping or wide gaps. The distributor of the flooring plays an important role to provide a consistent product for the contractor to deliver a quality installation.
If you measure the width of 10 boards, which would be 22.5 inches if the flooring was laid tight to what you get on your floor, you can extrapolate the moisture content that existed when your flooring was laid. A wider measurement would mean more moisture content. You can compare new flooring to older installations which do not have so wide of gaps.

Thanks Pete for the reply.

But the problem seems to affecting the old refinished floors which is the majority of the sqft. Only the kitchen and foyer was new install.

Also it seems to be more so on the 1st floor.

Could it have something to with the unfinished basement?

The old floor as laid when it had a high moisture content.