If acclimation readings were taken, and I bet they were not....there isnt really a lot you can do. They will narrow considerably. Credit card thickness gaps are considered acceptable. 4 inch solids are going to be climate finicky and will move quite a lot. The movement between a 4 inch and 2 1/4 will normally be twice as noticeable almost. Acclimation is meaningless without moisture readings,is meaningless. Other than a redo, there is nowhere to go with this. Are you maintaining humidity levels at 35% minimum? If hot air heat and humidity is dropping below that number...there it is and you will need a humidifier to put the moisture in the air.

Well at least your wood acclimated for 10 days. We have run into the exact same problem with 4 inch flooring. We had the wood milled for us and then installed by a company not in the normal circle of the mill. The installer **should** have taken moisture readings but didn't. The GC **should** have overseen the process but didn't. The manufacturer **should** have checked the moisture readings upon providing the material and given a stern warning to acclimate the wood but didn't. As a result we are looking at a re-install of about 1000 ft. of reclaimed oak flooring and associated cost of between $6 and $7K. Nobody is offering to help us out on this cost as of yet. I bought a moisture meter (Delmhorst) and measured the gaps with a micrometer and estimated that our flooring upon installation was around 16% MC; and now it is around 9%. Our gaps are around 1/16"--the size of a nickel.

We have looked into filling with putty but have been advised that we should not treat putty as grout. We have looked into filling with slivers of wood, but have been advised that they will work their way free eventually and may become a hazard.

We could leave the flooring as is in a couple lesser-used areas (closets) but I'm concerned with all the dirt that will fill the gaps.

Good luck in your resolution!

There is a very good reason, you don't see wide plank flooring in New England.

You are seeing why in the dry winter, shrinking months.

A 4" plank has the shrink and swell of 2, 2" strips.

Where the 2" strips get some gapping, say a finer 1/32, the 4" is going to have wider 1/16 gaps.

Get some humidity back into the residence, without creating dripping window panes.

A thermo-hygrometer is very helpful. Keep your rH around 40% if you can.

I don't think it's true that "you don't see wide plank flooring in New England." We have some of the oldest houses in the country with wide plank flooring! However I agree that moisture control is of great importance. My 4 year old floors are up to 11" wide and haven't moved at all. If the product is appropriately dried before milling, and humidity levels are controlled in the house and checked properly before installation, there shouldn't be any problems.

In the complaints I see here, egregious errors caused the floors to move. The manufacturer "used wet wood" (why on earth wasn't the wood kiln dried before milling?) or the installer didn't acclimate or meter the flooring and subfloor (installation 101). And in real life I've seen DIYers put down flooring over new concrete (which continues to release moisture) or store it on the building site before mechanicals are installed. The manufacturer has little control over what happens after delivery, aside from refusing to deliver it to those circumstances.

The wider the board, the more **potential** of instability. Good installers are hesitant to install any exotic wood > 3" wide (exotics 'tend' to be more unstable)..