Roundhouse build: making a Reciprocal Roof

| Building, Natural Building | comments | Author :

1307 reciprocal roof - 01

Reciprocal roof frames are self-supporting structures that date back to the 12th Century. They are used in Chinese and Japanese architecture, as well as being something that Leonardo Da Vinci explored in detail.

The interlocking nature of the separate members creates a complimentary tension that, ultimately, results in an extremely strong, self-supporting roof.

The theory of it is surprisingly easy to follow, once you understand what’s going on. And so a reciprocal roof seemed the perfect choice for our recent experimental strawbale roundhouse that we built at Milkwood Farm… 

Shane, Nick and Floyd practicing making our reciprocal roof on the ground... to check we had everything right.
Shane, Nick and Floyd practicing making our reciprocal roof on the ground first… to check we had everything right.
It all seems to be working...
It all seems to be working (we were a bit overcautious on the ropes)…
And it's weight bearing and performing as it should! Huzzah!
And it’s weight bearing and performing as it should! Huzzah! Now take it apart again until we do it for real…

One of the advantages of a reciprocal roof frame is that you can use roundwood timbers to make it. This can be a big advantage if you have acces to young trees (or bamboo) for polewood, but no access to milled timber.

The theory of how to build a reciprocal roof is fairly straight forward. To learn what we needed to know, we prettymuch just watched videos of Tony Wrench, who is both very experienced and eloquent in the ways of describing how the heck to build there things.

The video which helped us most was this one:

If you can, it’s a good idea to practice with some lightweight material (we used bamboo) if you want to understand this process before doing it for real…

sam reciprocal


And with that demonstration from Sam Vivers, we were off to do the real thing, using green eucalypt ‘bush poles’…

Nick finishing off the tripod that will support the first number of beams until they become self-supporting
Nick finishing off the tripod that will support the first number of beams until they become self-supporting
And off we go...
And off we go…

1307 reciprocal roof - 15

1307 reciprocal roof - 16

Sam Vivas 'persuading' all the beams into their rightful and relative places...
Sam Vivers ‘persuading’ all the beams into their rightful and relative places…
Last one goes into place... heave ho.
Last one goes into place… heave ho.
The frame is up! The two extra long beams that come down to ground level are to create a undercover 'lean to' at the back of the building
The frame is up! The two extra long beams that come down to ground level are to create a undercover ‘lean to’ at the back of the building

We attached these poles to each other with rope firstly, and a chain around the whole thing to be extra safe. Once everything was in place, the timbers were secured with bolts.

1307 reciprocal roof - 20

1307 reciprocal roof - 21

Next up, time for cladding. This will eventually be a living roof with a meadow growing on it, But there’s a bit of work between here and there. We clad the frame with hardwood floorboard offcuts, which will then form the internal ceiling.

Above that will go insulation, waterproof membrane, soil and plants. All resting on a very strong, self supporting, roundwood reciprocal roof…

See here for the building history of this roundhouse to date.

Floyd oversees the beginning of the ceiling cladding
Floyd oversees the beginning of the ceiling cladding
The hardwood cladding, that provides the base for the living roof on top, and the ceiling beneath…
Nick and Floyd take a breather
Nick and Floyd take a breather
Shane finishing off the cladding
Shane finishing off the fiddly bits..
Seems almost a shame to overlay this beautiful wooden form with other things... but the living roof will be worth it.
Seems almost a shame to overlay this beautiful wooden form… but the living roof will be worth it.


Our next Natural Building workshop is coming up soon…

It’s an intensive, hands-on four day workshop for anyone who is dreaming of building their own earth friendly home. Learn how to build with a variety of natural building techniques: light earth, strawbale, cobb, roundwood timbers, reciprocal roofs, lime and mud renders and more.

>> More posts about Natural Building here…

Big cheers and thanks to Sam Vivers and to all who contributed their energy to this build, and to Floyd for most of the photos above.

See the comments

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8 responses to “Roundhouse build: making a Reciprocal Roof

  1. Excellent! A beautiful solution for the roofing of this great project – on a similar note and piggy backing on the previous comment – you can use this principle with a circle of people – standing in a fairly tight circle and all facing the same direction, in unison, slowly start to sit down in the lap of the person behind you and amazingly, the whole circle can sit without any support other than one another – yes, there’s plenty of fun to be had falling over and it usually takes a few tries but when the group is communicating and coordinated, it’s a remarkable moment when we all sit and feel comfortably seated (reasonably comfortable that is) and providing support for one another – it’s a team building/group communication exercise with many obvious metaphors to be drawn from the activity – thanks for sharing this excellent project! great to see it coming together with with such rustic elegance –

  2. Reblogged this on Blueberry Girls MIRACLE and commented:
    If you don’t already follow Milkwood, ohmigosh you totally should! In this post they describe self-supporting reciprocal roofs, which are not only sturdy, but gorgeous.

    Funny how so many incredibly sustainable things just happen to be gorgeous, isn’t it? Huzzah!

    They’re a huge inspiration for us, and a fabulous example of many of the things we’ll be doing. Here’s to more and more people exploring sustainability and general awesomeness!

  3. Do you have any information on how people have gone about getting council permision for various alternate building methods in Australia, particularly if you intend to live in the structure? I am very sensitive to many modern building materials and the assortment of acommadation options I have tried have ranged from unsatisfactory to downright horrible in terms of health outcomes and or general living conditions. If we manage to scrape together the money to buy a parcel of land, is a leagal small economical dwelling constructed out of natural materials a realistic dream, or are structures like this one and the earthbag dome etc. just some nice farm outbuildings?

    1. Hi there El,

      Depending where you are in Australia, there are standards for development that must be adhered to in order to obtain consent. These are usually the Australian Standards – you can purchase and sometimes view them free online.

      Most exempt development (development not requiring consent from Council) is required to comply with Australian Standards, especially if you are going to live in it. In NSW in order to live in a structure you need permission and this ensures you can get insurance if you wish to do so, etc.

      However, in many cases these innovative forms of development don’t comply with Australian Standards – this is because these standards are usually based on very common, cookie-cutter-type developments. In these cases if you wish to get consent to live in a structure you would need to consult an engineer and pay them to examine the structure and provide their stamp of consent (and their insurance).

      This is all in regard to obtaining permission for development. If you want to simply build a structure that is exempt (generally not for living in), or if you want to build without permission and live in it without Council knowledge (you won’t be able to be insured and could be issued penalties if they ever find out) you wouldn’t need to go about doing any of these things. I would still consult with engineering experts and / or builders in order to make sure that your structure is safe enough to withstand whatever the wind rating is in your area (you don’t want the roof to blow away!), the span and load bearing capacity of the building and the suitability of the materials used.

      In an ideal world, this would be the only reason why Councils and the government regulate your build, and in many ways they do still. The bureaucracy gets a bit stifling though!

      Good luck!!

      (Urban and Regional Planner)

  4. RE: EI,

    I work for a planning district in the Province of Manitoba in Canada. Our zoning rules do not require a permit for structures less than 120 square feet in most cases. Some rural areas in the United States do not require permits at all. Check with your authorities. Otherwise, you will probably need to find a structural engineer to design this in order to obtain permission to build. However, finding a structural engineer who is willing and knowledgeable enough to do this kind of alternative work may be a challenge.

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