Hi, I’m looking for some advice as to how to prepare the upstairs floor of my mountain home for hardwood. The carpet is removed and the current floor consist of tongue and groove cedar 2x6's nailed to 4x12 floor joists on 4 foot centers. To eliminate the springiness of the floor and the squeaks, I was going to sheet the floor with 5/8" plywood before installing 1/2' engineered oak over the top. I plan to nail the plywood with ring shank nails and the staple down the hardwood. Do I need a moisture barrier, if so, where? I have ¾” solid oak on the floor below which is nailed directly to the 2x6s and it's doing fine after 5 years. I need the extra 5/8'" upstairs for my transitions and jams. Is what I'm proposing sound correct? THANKS

Sounds like a good plan. I'd make sure those 2 x 6's are nailed down tight first and go with 3/4 ply/

THANKS Where should the moisture barrier go? Between the 2x6s and the plywood, or between the plywood and the hardwood?