I own a 2 1/2 story home built in the 20s. We bought it as a fixer-upper and have done quite a bit of work already. The attic has two sides with windows, and the usable space is basically a T-shape. Someday we would like to finish the space and make it a bonus room. Currently, there is no insulation at all, and the attic floor and the roof are both framed with 2x4s. We thought about just blowing insulation in there for now, but don't want to waste the money and effort to pull all that back out. We were told that the 2x4s wouldn't be sufficient support if we ever wanted that to be usable space. So, we added a couple beams on the floors below where we were able, but that didn't fix all the areas.

I'm trying to come up with ideas on how to make the floor stronger. If I rip up the floor and put 2x6s or 2x8s alongside the 2x4s and nailed them into place, making sure they were over the walls below, would that create enough support just because the boards are thicker? And if so, would 2x6s be sufficient? Or should I go up to 2x8s? Then, can I insulate that new floor before putting down the sub-floor? Someday I need to insulate the roof too, but we don't really have much for ventilation up there yet, so I need to do that before insulating the roof. At this point, I want to get it at least somewhat insulated before winter, while not doing unnecessary work that will cause wasted money and more work later. And I want to make the floor stronger so we can use it for storage.

use 2x8 for new floor joist. This size is relative to span of beams.

If going to make it a room in near future, would recommend insulating rafters not floor.
Unless u will be wanting to deaden sound from new room or old room.

Chuck

We don't plan on actually doing the finish for a few years, so we were thinking we would insulate the floor so that we have some sort of insulation in the attic. It shouldn't hurt to have the floor insulated once we finish it right? I guess 2x8s it is! :)

U should be fine

Chuck