I am trying to come up with hip roof designs or construction methods which would eliminate the need for collar ties, spanning beams, etc. I have some ideas but would like any input. Thanks.
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You gotta give us more detail than what you did.
But here is a simple answer. Locate your interior walls below so you can post-support all ridge members. Post-supporting structural ridges eliminates the need for collar ties.
Gene,
I apologize for the lack of detail. Trying to get out the door for an appoitment is not a good time for research. My main issue is that this is an open floorplan (sun porch addition) with no interior walls. I have been thinking about some sort of structural top plate/header combo which would not allow lateral spreading. A steel plate running the full length of the top plate has also come to mind. The size of the addition is not great (16'x16'), but the engineering challenge still exists. Thanks for your input.
If you want a vaulted ceiling under a hipped roof, a good truss manufacturer can show you how he can do a roof structure with scissors and sloped-bottom monotrusses to yield an inside hipped shape under a topside hip.
It'll be a whole lot easier.
Don't think plating a wall with LVLs will structurally solve the pushout you get from rafters coming off an unsupported ridge. That top plate isn't trying so much to bend. Pushout against a nice rigid top plate will cause the wall when it bends out, to be nice and straight. Nice and straight, but still bent out.
Sorry Gene, have to disagree with you. We're talking about a small addition, only 16x16, so the rafters are only spanning 8'. An LVL top plate is just a horizontal beam. The engineering on it would be relatively simple, with the forces comparable to a structural ridge beam. The flatter the pitch, of course, the more lateral force there is. I think this would be easier and look better than getting into scissor trusses (no offense Boss Hog!).
"no offense Boss Hog!"
No offense taken.
The first post didn't mention the span or vaulted ceiling. I probably wouldn't mess with trusses on something that small either.
You are such a good friend that if we were on a sinking ship and there was only one life jacket....
I'd miss you a lot and think of you often.
Hoss, Gene's idea is good, but if you want an open floor plan I've seen hips and mansards built/retrofitted with LVL's for top plates. This would have to have an engineer's stamp. The ones I saw were something like 3 1/2" x 12" or 14", with custom steel connectors at the corners.
Mike,
Great idea; something similar had come to mind. I have seen an article in which a builder used steel angle brackets on the top plate to receive the hip and tie the corner all together. My main concern is where the end king common and side king common rafters intersect the top plate of the walls and keeping the walls from deflecting outward due to the ridge wanting to drop. Maybe LVL at the top plate in combination with steel plate would be adequate. Thanks for your input and any additional would be welcome.
Another alternative to your question might be a continuous plywood box beam framed around the interior encompassing the top plate and the 1st 18" to 24" of the rafters.I tore the collar ties out of an attached garage glued and screwed a box beam on the 3 free walls & converted it to family /great room. The beam added to the room providing a soffit for wall wash / indirect lighting. I certainly would consult an engineer before attempting this on any free standing building of any size.
Roof trusses?
Or is that too obvious?
A: When a nymphomaniac tells you: "Let's just be friends."
Roof trusses?
My memory is feeling like it came out of a reject 286 today--I seem to recall a neat truss form/shape that spanned the diagonals of a hip, the remaining trusses bein more 'normal' from that starting point.
Or am I having one of those flashbacks Bubba* warned us about ?
*"We Are the People Our Parents Warned Us About" off of A1A, I thinkOccupational hazard of my occupation not being around (sorry Bubba)