Last night, I wrote up a blog entry for Green Building Elements about building a reciprocal roof frame. I wrote a little bit about the concept of the design, the history, and my own experience building a reciprocal roof. I was inspired to write this due to an overall lack of information out there about the concept.
If you’re interested, check out the full article here: The Reciprocal Roof: Beauty, Strength, and Simplicity in a Roof Frame
(P.S. That’s Liat on my roof!)
Recently, with the help of Traci, I finished raising the last of the secondary rafters for my reciprocal frame roof for a grand total of 28 poles.
They are affixed to the primary rafters with a big spike nail for now. Today, I finished bracing them with small two foot long pieces of roundwood. I slipped this roundwood underneath the rafters to help spread their weight more evenly through the cob. In addition to each rafter, this wood is pepper nailed, and the two are tied together with strong steel wire. It looks pretty messy (see below), but it will all get buried in the topmost layer of cob. Hopefully this is sufficient to keep everything steady and locked in place.
The weather has been grand lately, with only a small amount of rain the other night. Today was quite breezy and it truly felt like fall. Within another day or so, I’ll be able to begin decking the roof with my new work exchanger, Jeff.
P.S. More photos of the reciprocal roof raising, including a rundown of the process is coming soon… I promise.
Ok, I’m still waiting on receiving some of the many photos that were taken during the reciprocal roof-raising the other day, so I’ll wait on the ultimate rundown of the details of that day and the frame itself.
Though I will say that things are now progressing again. I am using the original poles as secondary rafters, one between each main pair. That means I will have a total of 28 trees sitting on my cob walls! Yikes.
That makes me wonder how much wood goes into a traditional gable roof. Granted these are very small trees, and you would hardly get but a couple of 2x4s from each were they to be milled, but still…. 28 trees sounds like a heck of a lot wood. It’s weird to translate pole wood to milled lumber construction.
Also, I want to say I am now a big fan of black locust. It is an incredibly hard wood and very rot-resitant. It is something of a “weed tree” (farmers usually like to get rid of it), and it grows quickly and easily. The bark is very thick but incredibly easy to peel off, and because black locust oftentimes has few knots, the peeling is just that much easier, too. Black locust is solid. Also, it smells almost like green beans when you strip the bark.
Here is the only video footage that I had captured of the second reciprocal roof frame construction. This is the final step, after removing the support braces from the ‘charlie stick’ (or temporary post): knocking charlie out of its support position.
As you might be able to see, the roof did not drop at all, since the construction was very tight. We actually had to pry the last rafter into position, which pretty much guaranteed that the frame would not settle once the charlie stick was removed.
Here’s the video clip (be prepared to tilt your head!):
What an incredibly arduous past two days, but oh the excitement! Yesterday I made a mad dash to transport twelve new black locust poles for my roof to my building site, and then I spent the entire afternoon (and into the evening) stripping bark. My body was aching, to be sure.
This morning I finished stripping the last of the twelve poles. At 8:00 a.m., I began dis-assembling the original reciprocal roof frame with the help of Tony, Tamar, Mark, Apple, and Arrien. It was easy work – much easier than putting the thing together. We jammed the charlie stick (the support post) back under the first rafter, and worked backwards to slide each rafter out. It went quickly and smoothly.
Then we re-positioned Charlie and started lifting the newer (and much beefier!) black locust rafters into position, tying them together with wire at the top as we went along. They were a little slippery, and slid around a little bit once they were in position, but they couldn’t go too far with the wire at the top and some wire around the butts at the wall.
By the time we were ready for the last rafter, the inner ring of the frame was already tight, and we pried the last rafter in with a bit of leverage at the butt end. They slid right into place and the roof was done. We took out the charlie stick and the roof stayed put – it didn’t drop at all since the construction was already so tight.
(The reciprocal roof frame from afar [it looks like some sort of alien structure!])
Overall, it went great. The new rafters are much stronger than the old ones and I am very satisfied with the integrity of the structure.
I plan on writing at length about this process in the near future. In the meantime, enjoy these few pictures!
(Tony was brave enough to climb the frame for a little photo opportunity)
Last week, I managed to cut down a dozen more black locust poles for my reciprocal roof frame. I will switch out the current rafters for these newer, beefier ones, and the old ones will become secondary rafters. Recently, I have been working more slowly thanks to some killer rainfall lately – last week, we had nine inches dumped on us! This year is truly incredibly wet. (Figures that I decide to build a house out of dirt during the rainiest year on record, too…)
I transported the new trees to my property with the help of a few folks, and hopefully I’ll have enough energy to strip them all this afternoon to have them ready to hoist up tomorrow.
Here we go again!
Ok. The long-delayed and long-anticipated reciprocal roof raising finally happened over this weekend on Saturday. It went smoothly, despite a bump here or there. The whole thing was up within a few hours.
However. I am going to take it all down and do it again (!)
There are some imperfections. The peak of the roof, or the inner ring is not centrally located, making the span on the west side of the house significant longer than on the east. The skylight hole is not totally circular (see above), which is ok, but again: could be better. There are a couple other things that could be improved, too.
Sometime soon, the poles will be taken down, and then hoisted up again, and it will be even better. More balanced.
I’ll wait to get into the nitty gritty of reciprocal roof raising until then.
Stay tuned.
Today, I found some red oak borer larvae living in some of my pin oak rafter poles. At least one of my roundwood rafters has been lying in the grass (on some pretty measly sticks of wood to keep it off the ground) with all of its bark intact since perhaps April.
Needless to say, I wasn’t happy to encounter them tunneling through the wood. I’m not sure how serious this issue is (thankfully, the wood wasn’t completely riddled). I cursed their existence generally. But I think the pole is still good to go for the reciprocal roof construction.
This whole roof business has been a bit like walking blindly down an alley for me, since I have never worked with pole wood or built a roof (or even helped to build one). I have been quite uncertain about the whole process thus far: whether or not my poles are strong enough, whether or not they are long enough, whether or not they are seasoned enough (this I know is not the case: most of my poles were only cut in March, but I’m going for it anyway), etc.
Well, I guess I’ll know at least some of these answers on Wednesday when I have a roof raising party and get the reciprocal roof assembly built!
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:
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!
(Image from Zone5.org)
Hi there, I’m Ziggy. In 2008, I launched The Year of Mud while building my first natural home. This blog is a collection of personal stories and experiences building with clay, straw, and wood over the past 15+ years. A few of the things that get me fired up are natural plasters, timber framing, & Japanese architecture. Since 2012, we’ve been hosting Natural Building Workshops so you can learn essential skills to build your own natural home.
