I am working for a local ymca repairing the gym floor. Large sections have a rotted subfloor from an old heat system. We did one patch about 10' x 20' with all new framing and subfloor and there is more to do. Naturally, the new flooring didn't line up with the old so we didn't even try to tooth it in. It was exactly the same width, but the gaps between the existing boards vary quite a bit and it started misaligning after about 5 rows.

Several of the members have been told that it should have been toothed in because it will expand from it's current tight installation and may cause the adjacent areas to buckle. Is that true?

We can tooth it in, but there will be a bunch of gaps between the boards as they go into the old floor. I haven't toothed in a large area like this before. I guess we would have to leave a gap between all the new pieces all the way down. But is there any basis to the expansion idea? The new wood has the low moisture content we test for before installing. The gym itself is old and not heated and cooled as consitently as a modern facility, but seems "normal" for gyms I've been in.

Does anyone know of a wood floor council or some other authority who has printed any type of guidelines for repairs like this?

Thanks for your time,

Thom Huntington

When you say "toothed", are you referring to weaving in the new floor to the old by staggering the butt joints back to factory ends? It sounds as if that is what you mean and are have trouble doing. It was common practice in older gymnasium floors to gap the floor boards periodically so the floor would not warp and buckle when the humidity levels would rise. Gym floors are typically maple and maple is a mover. How often gaps were intentionally left would depend on the size of the floor and the geographical location. I would bet if you waited till summertime, when humidity levels are highest in most areas ( except desert climates ), the old floor will expand a bit and they will not be as large or have as many gaps. This is common in older gyms without modern climate control systems. Older ones usually just had a huge furnace hung from the ceiling. Most had no AC unless it was added later. They just had rows of windows near the ceiling for ventilation. These conditions, along with the great expanse of maple flooring, required expansion gaps built into the floors and very large expansion spaces at the perimeter with large, plastic like cove mouldings that had vents in them to allow the space under the floor to vent as well.

All that being said, you should make every effort to weave the new flooring into the old and keep the existing expansion gaps. Increasing the humidity to normal levels may help with the install. You may want to contact the MFMA ( http://www.maplefloor.org/index.htm ) and discuss this with them. They have a technical questions dept.

Hi Gary,

Thanks much for the reply. You have described the setup to a "T". There are large expansion joints on each side and rows of window near the top. We can weave the ends in no problem from a technical standpoint - just wanted to make sure it's worth the extra expense and as you point out maple being a mover, it certainly is.

Trying to help the YMCA out as much as possible as money is tight - like everywhere.

Thanks for the link - that's exactly what I was looking for.

I suppose we should take the last board out of our previous 10' x 20' patch and rip a bit for a looser fit to give room to expand. What do you think?

Thanks,
-Thom

Without seeing what you're doing or up against, I shouldn't give specific advice. Call the MFMA tech line.