Army grunt
Platinum Member
Build it with a gambrel roof This will give yo open vaulted look. Its easy an its been used for many years.
Army Grunt
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Army Grunt
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Oh boy, these threads are fun. I think I'll throw in my 2 cents, get a beer and sit back.
My recollection of the building code is that collar ties, rafter ties and ceiling joists are three distinctly different things. Collar ties, as noted are in the top 1/3 of the peak, prevent uplift splitting of the roof, and are not intended to prevent wall spreading. rafter ties are usually about 1/2 way up or less and are qualified to prevent spreading of the walls. Ceiling joists can function as rafter ties if required. Depending on the loading conditions, rafter ties can be allowed as much as 4 foot spacing.
If proper ties are used, the ridge pole sizing is immaterial, since it only stabilizes the rafter spacing. Using a large beam on the ridge will allow you to do away with ties completely if you can prevent wall spreading. I know a structural engineer who put a peaked ceiling on a 30 x 30 room by designing a steel belt to wrap the top of the walls.
Given the problem originally stated, I still think rafter ties and no ceiling joists are way to go. Maybe collar ties are now required by some codes, but they didn't used to be. I've built some good sized roofs with just rafter ties on every other rafter and they passed inspection.
Update- I stopped into my local (non-box) building supplier, and discovered that 20 ft dimension lumber is as common as dirt. Problem solved. In my forestry work my mind is set to think in 16-ft increments , and any logs greater than 16 ft are rare and special-ordered.