By sheer chance, I found this YouTube video in which several builders remove the ‘charlie stick’, or temporary support for a reciprocal roof frame. It looks like it is perhaps Tony Wrench’s account, but unfortunately he has no other videos about the building process. But this is indeed helpful! It gives me clues about the construction process:
- The charlie stick does not seem to be buried at all, which makes me think that they simply braced it (making it easier to remove later)
- The whole structure does settle once the post is removed, but not much, so the pitch is indeed “what you get”
- The top of the rafters look to be left untrimmed to their final size, which I assume gives the builder some wiggle room
The past few days, I have been dwelling quite heavily on the roof design for my cob house. I will be constructing what is called a reciprocal roof, a self-supporting structure composed of pin oak and black locust poles. Reciprocal roofs are round and spiral-y, perfect for round structures. They require no center post and are apparently “simple” to construct, requiring no experience. Plus, they look great, too.
The only downside to building a reciprocal roof is the apparent lack of really comprehensive information out there on how to actually do it. Running a Google search for reciprocal roofs results in a few decent hits, but still, there seems to be a dearth of hard information on how to go about making a reciprocal roof from start to finish.
The best resource I have found thus far is Tony Wrench’s book, How To Build a Low-Impact Roundhouse. You can see some photos of his design here. Wrench has some good sketches and a decent amount of how-to information in his book (which, by the way, is pretty hard to find), but I’m still craving more. Perhaps because my case is pretty different from his and I want to be reassured that this thing is going to work.
The main difference being that my walls are load-bearing, with the reciprocal roof rafters resting directly on the cob walls. Oh, and my house is also not totally circular… That makes a big difference, too.
But anyway, here are a few other sources of images and information for the prospective reciprocal roofer:
The LessPress Snail Cabin has a reciprocal roof made with dimensional lumber. Also, be sure to check out their Excel spreadsheet for calculating beam lengths and positions for both circular buildings and otherwise
Zone5 has a brief description with some images of a Tony Wrench-style reciprocal roof construction for a roundhouse here and here
Check out a scale reciprocal roof model and design using dimensional lumber at Casa de Baro
Cae Mabon in Snowdonia of North Wales features several buildings with reciprocal roofs. Images here
Simon Dale’s ‘low impact woodland home‘ has a gorgeous reciprocal roof with gnarly rafters and beautiful slab decking
For math nerds, visit The Pavilion for a very technical description of how reciprocal roofs function
Design Forward has a very brief snippet about the history of the reciprocal roof design, which was invented by Graham Brown, who says: “The structure demonstrates a principle that is fundamental to life on this planet - a simple natural principle: All life is connected.” (Unfortunately, Brown’s website is down…)
This is mostly what I have been reading and looking at for inspiration. I guess the only way to determine if my own reciprocal roof design works is actually making this thing. Soon enough, I will know!
Hullo. I am Brian, but I am also called Ziggy. I'm a 24-year-old currently living at Dancing Rabbit Ecovillage, learning to fulfill my desires to live more sustainably and self-sufficiently. There's a growing need to help shape a more eco-conscious, less destructive, and healthy culture, and I hope to share some of my experiences living in a community that values these qualities on this here blog.
