arched framing

[busted knuckles]

How are these framed? I really like the arch, looked at the arched cabins website, but would like to stay away from steel.

[busted knuckles]

Is it possible to curve 2x4? Ho would i talk to about that? Another example

[MushCreek]

It looks like an upside-down boat, so the same principles apply. In boats, they either used bent ribs, or sawn frames. To make sawn frames, you would have to piece together a number of shorter pieces of framing, and then figure out a way to hold it all together, such as glued plywood gussets. My preference, being an old boatbuilder, would be bent ribs. I would make a form out of multiple layers of plywood, then steam bend thin strips of wood and clamp them into the form. Once dry, you would disassemble all of the layers, apply glue, and then clamp them back into the form. This would make a very strong rib, and be a LOT of work! The wood for the layers would have to be good bending stock- straight grain white oak- no knots! 1X stock would easily make the bend if steamed.

Made heavy enough, you wouldn't need that many ribs, and they would look really cool partially exposed on the inside, all sanded smooth and varnished. If you have building codes where you plan to build, good luck convincing an inspector that it was a valid building method.

[busted knuckles]

Hmmm. It sounds like it would take a while. No building codes to worry about.  How about bent steel 2x3's but on the inside, to avoid thermal bridging?

[Don_P]

The most common way in wood nowadays is to use glulams custom made for the job.  Those exposed fascias on the double cabin pic are gonna rot and lead water back in from the looks of it. There is a similar curved batchelor cabin nearby that did something similar, the roof is a roll up door like the ones on mini U stor it garages spanning over the 2 endwalls with no interior ribs. Using something like structural pandeck you could probably work out loads/spans on such a thing. Old gothic arched dairy barn rafters were either sections of wide lumber with a curve sawn on the ouside, built up with staggered joints and lots of nails, or strips of 1x for top and bottom chord with spacer blocks between. Going older, a cruck frame is made by finding leaning trees with a curve and using them.

If you can wrap a steel strap around the tension side of the bend and firmly affix it so that it cannot slip, you can seriously bend a piece of wood

[JRR]

This might be a good application for a steel-reinforced concrete detail.  It would require a bit of study, but once the design is completed and the re-usable form(s) built ... a person could build several matching ribs (or even "half-ribs") that could lead to a successful project.  Insert-nuts could be designed into the ribs so that attaching wood strips or sheathing and inner walls could be simple.

[Don_P]

 That would be neat. I've always liked gothic window tracery details, they'd fit in the gables.

[busted knuckles]

The concrete is an interesting idea.

[UK4X4]

Whilst searching something else....came across this design of arched building, each frame member a straw bale apart.....looks like a smart design to me !

http://www.strawbalehouse.co.uk/index.html

[John Raabe]

Very unique structure. Elegant too.

[stricsm]

Here is another example using a Stimson Bow Truss (Stimson Marine Plans):

http://www.permies.com/t/35419/natural-building/Hoop-quonset-hut-type-building