We are presently restoring a 1,250 sq. ft. log home built in the early '70s, sited on a spot without a leaf of shade over the roof. The pitch of the original roof (built of trusses) is approximately 1:4 which strikes us as being pretty low even for the southern Missouri Ozarks where there is now and again a fair amount of snow come winter, and the avg. yearly precip. is
43.6 inches.The structure was built of oak logs from 6 to 10 inches in diameter and raised in three stages--leaving a central, original structure of 28 x 22 with later log additions either side 25 x 14. Standing in front of the place you're looking at an overall log-built broadside of 50 feet with north & south additions indented by three feet at the front, but forming an even exterior at the back. The roofs over the north and south additions are approx. one foot lower than that of the original central building.
We want to frame one roof (at an increased pitch) over the entire building, leaving the original roofing in place. We would superimpose new ridge beams and rafters from either side of the stone masonry chimney to both gable ends about two feet higher than what's there now, to leave at the peak that much ventilated air-space covered by Ondura corrugated asphalt impregnated fiberglass--with no plywood sheathing, but a framework of planks over rafters (16" on center) spaced about 8 inches--wider if feasible.
This would be ventilated from both gable ends and at the soffits, and further so by fans installed at gable vents.
In short, we want to build a condition of shade over the original roof. Can this be done, or are we just dreaming like the pair of amateurs we are? If otherwise it seems a sensible plan, we'd want to remove those three layers of baked, crumbling shingles from the original roof surface and put down some form of rigid insulating material, such as the commonly available foil-faced sheathing or whatever would stand up to the heat--there would be at least 6 inches of ventilated air space at the new soffits between the corrugated roofing and the insulation sheathed original roof.
Can this work?
-- Mackie