As a PS instead I am about a third of the way through boarding out our main attic. I'm laying a combination of 2x4s and 2x6s at right angles across the joists that hold the upstairs ceilings up to level things out (our roof seems to have been built by the descendants of "Little Bill" from the Clint Eastwood move "Unforgiven"), and then laying the boards on top of those. I'm taking the opportunity to put an extra 6 inches of insulation on top of the 10-12 inches the builders put in. I'm also adding another 6 inches under the sloping roof and putting an extra layer of radiant heat barrier (rip-stop aluminized plastic sheet) over that. That'll probably save me at least $50 a month anyway, and give me a shedload more room for her Majesty's collection of "stuff".