Carpentry and Woodworking - Applying 3/8 plywood on top of 3/4 wood planks??

My subfloor is made of 3/4" wood planks from back in the days. I want to place 3/8" plywood on top for a more solid floor and less creaking. This will give me a 1 1/8" thickness. What size nails should i use to nail down the plywood if I want it to reach the joists?

Thanx..

Some areas will take screws while others will be nailed down, wanting to know both sizes.. Thanx

I'd use 8 penny nails - 2.5" although a 2" screw would probably be long enough. I'm just a painter, the carpenters will likely chime in later:D

First, adding 3/8" plywood will not result in a floor that is much more substantial than what you currently have. 3/8" plywood has very little strength. Second, if the creaking is due to the nails in your existing 3/4" decking, the offending nails should be located and pulled. Driving a screw next to the existing nails may help.

Marksr is right about the 8d nail. If you choose to nail, use ring shank. If you screw, use a 2 1/2" deck screw.

Definitely "deck" screw, not sheetrock screw. I would opt for the torx head deck screws. Lotta screwing power without skipping.