Q. I live on the third floor of a triple-decker and when I do my laundry the floors shake during the spin cycle. The house was built in 1890 and the floors are original. The planks are nailed in and have been refinished a few times so they are very soft. The floors also shake when walking through the unit, so I know it is not an issue with an unbalanced washer. If I were to replace the subflooring, screw it into the joists real tight, and maybe even sister a few of them up, would it help ?
— Ross Botelho, by e-mail