I have a new project involving a Hip roof. I must admit that this is an area which I have never ventured.
The structure is 24 x 24 with one corner cut off where the entrance will be. The roof pitch will be 6:12 and equal on all sides. The client prefers that there are no posts in the floor area.
If anyone has a concept they may want to share or a picture of something they came across it would be appreciated. I have not seen any good examples from which a concept could be adapted.

Thanks in advance for any help.
Thane

What do you mean by:

Corner cut off? Does the roof still cover this area, but it is 'exterior' space?

No posts in the floor area? Does that mean 24' clear span from wall to wall?


Initially - without knowing snow, wind, live loading - I picture 2 king post trusses along the hip lines. 1 truss can be 'complete' and flown in as such. The other fits into the sides of the first truss, tying through the king post. Or you can do 4 triangles that meet in the middle...

Or one could do 'drag on' beams, or maybe a boss pin and tension ring top plates...

from a building in montreal that i visited:



random images linked from the web
small:




large:

Um, there is some good food for thought.

"Or one could do 'drag on' beams, or maybe a boss pin"

I like that idea. With a square wall plan and an equal slope around you are building a "pyramid" on top of the walls.

I think Mike's second picture(with the addition of more jack rafters of course) would be the way to go.

Mike, good looking roofs.

Those are awesome pics Mike.
I will propose a plan with a full roof but missing a corner post.

Pic #3 looks very suspicious, I like the next one though, nice direct joints in tension, heavy splines to take the remarkably high horizontal forces resulting from a low pitch roof.

I've never been a big fan of curved timbers in bending or tension, not natural. They are pretty but I lean toward simplicity, form follows function. However the second to the last is very sweet! The reverse shoulder cut on the "spring loaded" curved ties...that's nice... the only reason not to like that one is I didn't think of it!

I always have to ask myself "Why, Why do they have to take the corner post out?" Or in many other examples I find myself asking why over and over for other reasons. Yeah, there is likely a solution to the corner post being removed, but don't we have enough complication in our normal life.

I don't see any examples of tie's at the plate level running from the corners, this puts a timber at 34', not all that bad. The king pin comes all the way to the tie, forming the truss. Most of the pictures look like smaller structures, with the exception of #3, suspicious to say the least. Also the roof slopes appear to be steeper than the proposed 6/12.

Tim

Folks, FYI, I with the exception of 1 and 2 I snagged those from the web.

#3 is from Trillium Dell, a respected group of framers. It is a barn restoration.

Here is more information:
http://www.trilliumdell.com/barn-restoration-barns-for-sale

i'm sure i'd break something if we analyzed it for snow / wind... but its a start.

Handsome!

However, my intuition tells me there will be a LOT of tension in those crossing collars.

You could reduce this somewhat by adding a post or strut between the dragon beam and the hip, as far inboard as you can get it.

What have you got for analysis tools? This discussion could turn into a very interesting 'process' article for Timber Framing.

Mike, that frame looks a lot like the frame in Rick Collins & Co.s barn in Pic #3, the one I described as suspicious. It's not entirely clear (to me) how the horizontal forces are resolved... apparently echoed by our fearless leader. Of course much of the worry can be relieved if you locate the barn somewhere that it never snows... of course a little steel can go a long way...