Conical roof

[robbshowe]

I am designing a round summerhouse for a client and have come up with the design for the main wall frame.  I was wondering if anyone else had done something similar and designed a conical roof frame to finish it off?  I didn't want to re-invent the wheel if someone had already solved this problem.  I am happy to share my design thus far with anyone interested although it may be wiser to wait until I make it and can send photos as well.  Its small - only 10' in diameter with a shingle roof.

[moonhill]

How steep is the roof?  It will be interesting to see what you come up with.  I first think of yurt roofs and tention cables.

Tim

[underdog]

Alot of waste material in that design.
Look at grain silo's

[beenthere]

Get into Arky's (Arkansawyer) posts about his "round" structures. He showed some pics that would be a good look-see for you, I think.

[robbshowe]

I've tried to find photos of any Arkansawyers stuff  in the photo albums but with no joy.  Please advise how I can access any of his work on round structures.

[witterbound]

Here is the thread...

https://forestryforum.com/board/index.php/topic,26121.0.html

[Thehardway]

Thomas-in-Kentucky did a conical roof on his turret,  I'm sure he would be glad to share.  Do you want this free-span or is a central post permissable?  Most of the free-span designs for polygonal structures utilize a tension ring design. 

Two companies that specialize in these types of designs are Deltec (free-span) and Topsider (central post)  you might get some good ideas from their websites.

I originally planned to build an octagonal home based on the early designs of Fowler.  They were a precursor to ICF using a formed in place wall system.  I abandoned this idea because 1) no one would finance it and 2) there was too much wasted plywood and roof material.

Books on carpentry from the late 1800's and early 1900's usually have a chapter or two on framing polygonal structures.

For a 10' diameter structure I would probably mill a rather large octagonal pendant style kingpost and spline in some ties.

[shinnlinger]

For something that small I would try to get a silo roof...Takes all the fun out of it but very effective and no post.  There was one here in the paper a few years ago that the guy only wanted $100 for.  It was there for a while and I was pretty tempted, even the wife thought it wasn't a terrible idea.

[robbshowe]

I have come up with an octagonal  design for the main frame with intermediate vertical nailers on the walls.  I will use 1/2" thick wany edged cladding slipped behind 4" wide vertical cover plates which in turn are fixed to the main posts through a spacer.  The cladding be cut to fit between two posts and over one nailer only to limit the amount of curvature required.  The vertical cover plates serve two purposes, to hide the joints and also to eliminate the need for fixings near the end of the cladding boards which would tend to split.  The roof will have a short central, octagonal post to house, eight rafters. Thanks to the guy who confirmed this as a practical option!  I will fit curved tile battens at 71/2" centres to which I will fit progressively narrower 2' deep shingles to.  I hope to use 1/2" thick flexi ply for the battens.  Careful layout using Autocad has meant I should only require two full sheets of this expensive material! Well I am off to make my usual 1/10 scale model to confirm my design is feasible.  For those who are interested I'll keep you  posted on my progress.

[Rooster]

Hey there,

I saw your post on the conical roof....I wanted to share my experience when I built a 10-sided cupola with a conical roof that was almost 14ft. wide, on top of a 60ft. diameter round barn.  Please take a look at my photos on the project. 









(Photos Posted by Jim Rogers)
I agree that the center post for the top of the rafters is key....the other trick is to build a laminated top-plate/ring to handle the bottom of the rafters attaching to the top of the outer walls.

If you have any questions please feel to call me.

Good luck,
Rooster
920-728-0353
saveabarn@yahoo.com

[Jim_Rogers]

photos added....

[SwingOak]

There was a round barn near the Pequest Trout Hatchery, just of Rt. 46 here in NJ. I've been driving by it for years when I went up there pheasant hunting, hoping the State would do something to preserve it - it's the only one I'd ever seen (I did ask once and was told there was no funding for it). It was a bank barn, about 40' in diameter, and had a definite lean to one side - it look like a slinky pushed sideways. I had hoped to poke my head in there last fall to see how it was framed and maybe take a few pictures, but as of October it had collapsed.

However it was built, I doubt is was more than 100 years old.

[ARKANSAWYER]

 








  This is an octagon roof.  I did a dome onetime (no photos) by taking long 1x4's and bending them.  To keep it from spreading we put a 3/8 steel cable around the top of the wall that ended up in the soffiett.   Have made domed trusses by gluing up short, over lapped 1x10's then cutting them round on top and bottom.  Could do a few timbers like the arch in a Burr Arch bridge.