We're installing a new 3/4" hardwood flooring in our 16 year old house. The sub-floor will require some flattening (leveling), but all in all it's something we can deal with. When looking at the joists across the whole house, we noted that the two portions of the space in which we would like to install the flooring have joists that are 90 degrees to each other. I've read that hardwood flooring should be installed perpendicular to the joists, and we'd rather not have the flooring change direction between rooms.
Is it a major issue to install flooring parallel to the joists, or should we consider reinforcing the sub-floor with another layer of plywood?
Thanks for any help! Ryan and Helen, Yukon Canada

How thick is the subfloor, and is it a single layer or double layer? If a single layer does it have a T&G?


The guidelines say for a single layer , less than an 1" thick, to either ....

Add a plywood underlayment over the existing subfloor, or
Install 2x blocking from underneath spaced 16" - 20" apart, or
Run the flooring on a diagonal

HI there, Thanks for the response. Our floor is single layer 3/4" OSB, not T&G. I'm thinking we're going to have to choose the smaller of the 2 rooms and reinforce that floor with plywood, or 2x blocking with the joists. The other section is built over an apartment so using 2X blocking in this sections will likely be much more of a challenge.
Thanks again! -r