We are looking to install 3/4" x 3 1/4" hardwood flooring parallel to the floor joists, the subflooring is 1/2 plywood over engineered joists, the home is 10 years old and we have not noticed any problems with the current carpeted floor.

The reason for parallel is we are meeting an existing 3/4" floor which we do not want to match with the same flooring; we are also meeting a tile floor.

What problems may I encounter.

With running in the same direction as the joists your biggest problem will come from movement in the subfloor and no stability for your new hardwood flooring.

A solution to this is having supports installed. The way this is done, is by cutting 2" x (whatever your joists depths are) and install them on the same center the joists are installed on. For example if there 16" o.c. Then you will install the supports 16" o.c. When your finished your subfloor should look like a grind.

Thats my solution that a manufactor would O.K.

Martin