Gaps between hardwood planks

Q: I had my 30 year old oak floors redone. There were some areas were we had removed a fireplace mantle where the wood was put in new. They sanded and applied 3 coats of the Glista (scary after reading about it on your site, and to boot, they used no respirators!) I just noticed today that there are small cracks between the planks where the has now separated, gaps between hardwood planks.

Can this be repaired by reapplication? Will they have to redo the floor completely? The old coating sure didn’t show separation before so what’s up with it pulling apart now? Was it the flooring guys not knowing what they were doing?

A: I think you need to add some moisture to your home climate. That is why the repaired areas are shrinking.

Follow-up Q: Would that be true for the boards that weren’t replaced? We are in Hawaii, so I didn’t think about the moisture..

A: I may have misunderstood your comments. I hope not. I thought you were saying the entire floor was developing gaps. Am I correct to assume it is just the new wood which was used for repairs? If that is the case, the guys should have checked it’s moisture content before using it to be sure it was close to that of your existing floor. If it was above normal, 7-9% it would shrink as it starts to shed the excess moisture.

Second follow-up Q: Well, yes it is by where it was repaired, but then it is in places where the floor wasn’t repaired too.. that’s why I thought it was weird. It’s just some places in the middle of the floor away from the repairs. It has been somewhat dry, so do I just wait for the expansion to fill the hole or do I need to reseal?

A: I would try to increase the humidity a bit but not apply more finish. That really won’t solve anything. Come to think of it, I need to get a humidifier myself. My hygrometer has been showing me readings of less that 30% RH, even down to 27%. Far too dry.

Related Q: We purchased an 8 year old waterfront home in April 2012. It had approximately 1000 sq ft of hardwood floors, which were cupping in places, finish worn off or thin in others. There were some spaces/cracks between some boards in the worn areas. We live in an area of high humidity in the winter. In the fall, just before the rains started, we had the floors sanded and finished with three coats of Swedish finish. During the last month, there have been increasing loud snapping or popping noises from the floor (we think), like someone dropping a number of heavy magazines or large books flat on the floor. In addition, large cracks (less than a dime width?) are appearing between a number of the boards. The noises appear to be more at night. We have the HVAC set at 70 during the day and 68 at night. We assume this is a humidity problem, but too little humidity in the middle of rainy season is curious? We have no humidifiers or dehumidifiers. Is there anything we could do?

A: Being a waterfront home, my guess is the floor cupped because it wasn’t properly acclimated before installation. It does sound to me like the popping sounds are from the boards shrinking during periods of low humidity. Swedish finish is a very hard coating. I don’t know how much it stretches but likely some of it has seeped between boards and dried on top of the tongue. If the boards shrink (a gap as thick as a dime would be considered normal, not large) something has to give and I think it is the sound of the finish breaking it’s bond between 2 boards.

I would suggest buying a hygrometer to monitor the humidity levels in the home. They are fairly inexpensive. Other than trying to control humidity levels within a range, I think you really are just looking at time to solve the issue unless cupping returns. In that case you are looking at another problem and another cause.

Follow-up: No cupping evident since we had them refinished two months ago. We will watch the cracks expand and shrink for a year and then decide what to do! We will learn to sleep through the pops I am sure! Humidity hovers around 40% + or – depending on outside temp and the furnace activity.