Q: I live in Alberta, and have had solid maple hardwood flooring installed over a new sub floor of 5/8″ plywood on my main floor. The strips were nailed securely and tightly by a carpenter friend who has done this before, and his floors always looked great for years after, so I know that he is doing it correctly. By the way, this flooring was reclaimed from a 55 year old house about to be demolished. The flooring was acclimatized in my house for a period of approximately six weeks before being installed.
I did bring in a professional hardwood floor sander/refinisher to finish the floor. It was only after the sanding and two coats of oil-based urethane were applied that I noticed and became concerned about the gaps between hardwood strips. I obviously had not checked closely before the refinishing began, so my mistake. I can only guess that being in this part of the province during the heating season, the humidity level was so low that the hardwood shrank appreciably.
My new furnace is equipped with a Generalaire by-pass humidifier, but unfortunately it was not connected during this whole process.
So, now I have halted the final finish coat on the floor, and have the humidifier working at a maximum setting.
It has now been three weeks with the humidifier working at a high setting, and I’ve been hoping that I would see a reduction in the gaps between some of the hardwood strips, but my close inspection reveals no change whatsoever.
I expect that the person I contracted to sand and finish my floor should have asked me prior to starting the job about humidity, but all he asked was whether the material had spent some time in the new environment before being nailed down, which of course it had.
What is my best strategy for getting this flooring to swell back to what it was when laid? My understanding is that finished and sealed solid hardwood floors will swell and contract with humidity changes, so is it not reasonable to expect that raising my relative humidity level will have this effect on the wood? Or should I just have the gaps filled, more urethane applied, and then hope that it will not expand later and cause me grief with the filler material breaking up?
I have considered getting a hygrometer to see what my humidity level is, and try to ensure that is 40% to 50%, but have not done so yet. I would very much appreciate any advice or thoughts you may have on this situation.
A: Interesting situation. First, I really don’t think you can blame the floor sanding company. They really have nothing to do with the gapping. If anything, applying a polyurethane coating to a floor would slow moisture movement from beneath the floor and cause the floor to expand if there was to much moisture, for example, coming from the basement. I do not think we can keep the humidity levels at 50% in the colder parts of Canada in winter without having moisture problems all over the house. You might want to check the environment below the floor to see what the readings are there.