The Wood Flooring Manufacturers Association (NOFMA) recommends that when 3/4" solid hardwood flooring is installed parallel to the joists, that the joists have blocking installed installed at a maximum spacing of every 24 inches between all joists under the hardwood system IF the subfloor is properly-installed plywood and below a thickness of one and one-eighth inches OR if the subflooring is properly-installed Oriented Strand Board (OSB) and is below a thickness of one and one-quarter inches.

If the properly-installed subfloor panels is at or above the above thickness(es), then no blocking is required).

Particle board is not a suitable subfloor material for nail down hardwood flooring.

More information can be found in: NOFMA Nail-Down hardwood Installation Information Tip-Sheet:

http://www.nofma.org/Portals/0/Publications/Moore%2009_03.pdf

_____________________________________________

There are two ways to do any job.

The right way and the wrong way.

Do it right everytime.

_____________________________________________

http://flooringworld.org/

_____________________________________________