I'm looking to finish my attic in the near future and there's one big question that I need to figure out in order to proceed. The joists are the proper sizes for a 40psf live load but depending on the span some areas used 2x8s and other areas used 2x10s. What is the cheapest way to make this so I can install 3/4" subflooring over the top so that it can be one continuous flat subfloor. In other words, how can I bring up the 2x8 areas 2 inches so that they match the height of the 2x10s? I know I could sister all of the 2x8s to new 2x10s but I'm figuring that isn't the most economical solution as 60% of the area I'd like to finish used 2x8s.

 

Put sleepers on top of the 2x8s.

 

Thank you, I couldn't come up with the term for what I wanted to do. Would I run the 2" sleepers parallel or perpendicular to the existing joists? If perpendicular which distance o.c. should I be using.

 

On top of the 2x8s... meaning right on top of them. parallel, if that males more sense to you.