I am planning to install prefinished solid 3 1/4" wide by 3/4" thick ash hardwood in my home using 2" cleats. I live in Canada, so the average indoor humidity difference between winter and summer is quite high, maybe 50%. I don't use air-con in the summer. It is early December now, so I expect each board to expand in width by approximately .01" between now and summer.
Is there any reason why I should not put small gaps of .01" between each board (using a removable shim) as I nail them down? I still plan to leave a 1/2" gap around the entire room, just in case.
I ask this because I don't understand how a tightly-fitted floor is supposed to expand at all. What happens to the nails around the periphery if the whole floor moves by a good fraction of an inch? Are they simply ripped or bent out of place? By 1/2 an inch?? Or does the 45 degree angle of the nails force each board (and progressively the whole floor) to rise up by the same amount as the expansion? And when they shrink back down what pulls them back into place? People walking on the floor?
In removing my old maple floors I saw no such evidence of major movement. So I ask, quite literally, what gives?
Best Answer
Do NOT install expansion spaces between each board. You want a very tight fit between each board and then leave an expansion space around the perimeter of each room.
First you’ll need to acclimate the wood to your house. This may vary by location and season, but generally the manufacturers recommend about 10 days.
Second, seal the floor (again, according to the manufacturer’s recommendation).
Third, lay the “sleepers” out according to the size of your flooring and the allowable span. Sleepers are NOT fastened to the floor. They are designed to “float” or slide depending on expansion of the flooring.
Next lay out the flooring (loosely). This will give you an idea of color, etc., but will also help acclimate the finish flooring. Gaps at the perimeter is based on the size of the room. When we do gymnasiums, we leave a 2” gap and cover with an appropriate base. In homes, we generally leave a 1” gap.
See MFMA recommendations for acclimation and installation: https://www.maplefloor.org/ForArchitects/Installation.aspx
Btw, to test your finish flooring, hold a piece vertically and insert another piece into the T&G edge. If it fits tight, it’s okay. If not, you’ll have problems with the T&G edges when you walk on them. They’ll snap and pop and drive you nuts. If it’s not tight (and supports the other piece of wood when held vertically,) then I’d send it back. (See MFMA guidelines.) https://www.maplefloor.org/Home.aspx
Btw, yes, I know it’s the Maple FlooringManufacturing Association, but is consistent with ash, etc. too.