Wooden vaulted roofs

DT91

New member
#1
Hi.
I rarely seen vaulted ceiling used on wooden structures.
For a long and narrow structure, the easiest way I assume should be placing the boards parallel to the longer side, like a series of ridge boards, so to remove the need to curve them.

I only found documentation for stone archways, but I don’t know if for wood would be the exact same.

- If you manage to interlock the boards to themselves and to the shorter-side walls, couldn't the vault be considered more like a single piece instead of composed of different quoins? In that case there would be less or no need for lateral reinforcement like buttresses and tie-beams, and the weight would distribute also in shorter-side walls.
Would there still be the need for tie beams and posts depending on length between shorter-side walls and the vault angle? For example, for a lowered arch, if I’m not wrong, there should be less need for posts since the shear forces and moments between quoins are smaller, but if the ceiling couldn't be considered as a single piece there would be definitely the needs for tie-beams or buttresses since the lateral forces would be stronger than on higher arches.
What about others type of reinforcement there could be the needs for?

- Depending on the length between the shorter-side walls I assume the boards could be thinner than the ridge beam of normal triangular roofs (since they just have to sustain themselves), but of course much thicker than the normal sheeting planks. I wander what the weight proportion between those designs could be relative to the thickness of sheeting. Actually I looked at this design boot because I like it and because I would prefer a thicker roof for sound insulation against planes that often pass over here.

Does someone has schemes or experience for something like that?
 

Sacajawea

Bobcat Woman
Silver Subscriber
#2
The issue would be curving the boards (crosswise; instead of lengthwise) that become the roof at the correct angle. That's going to vary as to which board (to the top) it is. As for posts and supporting weight, there's the materials used - and snow/wind load if any.

Might be easier to calculate if there were a series of angles, instead. That math is beyond me.
I can "see" the problem; can't solve it with math.

But I would never try to support any roof, without posts every 8 feet; 10 max. And I couldn't exactly be confident in 10 ft. Just my gut feel on the problem.
 

The Branch Manager

Orange Man sofa king bad
Gold Subscriber
#3
I was "forced" (too lazy to do it the way I originally designed) to redesign the bunker. It's basically a stacked log structure now with narrower (12 feet instead of 16' roof beams) and 40' long walls. Old was 20x20. I could have continued, but I'd have needed a center truss with poles underneath and I wanted no poles. I'm building it above ground then covering with dirt. I'm going to mock it up this time with Lincoln logs and balsa, my corner construction might interest you. I'll try to update this later tonight with a pic. It might help you visualize your problem.
 

240Geezer

Well-known member
Brass Subscriber
#4
Have you tried searching the web for what you’re looking at. I know there’s a bunch of different calculators and web sites for such.
At least images most likely post and beam.
I’ve never seen the inside bones of an arched roof but I always imagined that the structure was made from multiple lap joints.
 

Sacajawea

Bobcat Woman
Silver Subscriber
#5
Timber framing, will sometimes use an arched roof; check out traditional norweigan styles & techniques. Based on 8 ft squares - beams were used to support various kinds of posts that supported the roof and transferred snow load stresses, wind, etc down through the multiple heavy posts. There are some basic rules about how heavy the first floor frame posts are; and of course, the foundation. I don't have those to hand, but it should be easy enough to find.

At various times, timber framing has been "fashionable" again. I'm living in a modern version now. The beams/posts are all joined by about 1/4" steel plates and lag bolts.
 

The Branch Manager

Orange Man sofa king bad
Gold Subscriber
#8
I'm fairly certain this is a very regional thing because I have not seen it outside of Southern Louisiana, but there are a bunch of pre 1900 buildings down here that have what I would call four-cornered Bell Arch type of room.

Basically I'm going to have to go eat lunch at this restaurant close to me or see if they've got pictures online so I can share this with you.

Basically what They are is one by sixes formed into an arch. Looks like they started on the inside and work their way to the outside to where they ended up with a square corner. Very hard to explain I'm going to have to go get some pictures of this place.