Reciprocal Frame roofs have only been around for about 20 years They were received as inspiration by somebody called Graham Brown from Findhorn and Jack Everick started them off in Britain I built a house from one about 15 years ago and now a lot of people like them because you can put them on a roundhouse an amoeba-shaped house You don’t even need level walls to put them on And the poles all rest on each other. So you start off with a support pole, holding one rafter up. You then put all the other rafters on that rafter. The you take away the support pole, or Charlie, as we call it. So you’ll see that in this video. So these will be rafters. And they’ll be arranged on to this henge round here. And we’re at present simulating where each rafter will go relative to each pole So that we can see how high the Charlie stick – – which is the scissors that hold the first pole – how high that should be. How high that notch should be above the ground. We’re going to measure from there to the height of here and then we’ll add that to the height of the henge add about 30cm for luck and that will be the height of our Charlie At present, we’re marking all these rafters as they come in and we’re taking account of the fact that some rafters are quite smooth and easy to manipulate because there are no particular land marks on them. Others have got knots and bumps so we have to take account of where they will sit on the rafter underneath. In this case, it’s a fairly straightforward rafter. It’s long so we’re not worries about enough overhang. So we can just take a fairly standard 60cm – we make a cross here. We measure another 24cm down to here. And we make a diagonal line there, which we will then cut out as a slight groove for the next rafter to sit on. So the cutting out will be done after we’ve done this simulation. Why 24cm? Well, we’ve determined that we want a hole about a metre across. See, that’s a metre. So it will be about a metre across. And how we measure the distance between that is we take the circumference which will be a metre x Pi (3.142) and then we divide it by the number of rafters. So we’ve got 3.142 x 1 m, which 3142, divided by 13, which tends to be 24cm! And this is what I call a “Rummy” Which is the distance between where one pole sits and the next pole sits. So if that is 24 in each case. We hopefully will end up with quite a nice tidy round circle. Ok, the next pole please. Next rafter. We’ve so far got 1,2,3,4,5,6,7,8,9 up… So it’s another 4 to go. Last one! So this is to ascertain what angle this cut should be at. We won’t have it through this plane, of course. We’ll only have it through that plane. Are we talking awesome? But you could move it anywhere! What’s determining where this end goes? That’s irrelevant. It is. It’s irrelevant. We’re looking at that angle there. But this could go here! No, it’s got to go over where the mark is. How many of these have I done? 15? Something like that. Now we’re starting to think about how high the tripod should be. I would say that you want to stand on the top rung or second to top rung. Sticking up this much so you can tie knots bang a nail in. Okay, so what we’re doing now is we’re trying to find the right height for the tripod. And we’re putting the tripod in which will be basically a working skeleton to climb up on. And then we’ll also be putting the Charlie, which will hold the first rafter. I’m Sarah Pugh and myself and Laura run Shift Bristol. We do a one year course which covers anything we think is important to sustainability on a practical level. So gardening and building and energy. Lots of group stuff. All based around permaculture with the idea being to give people an idea of holistic thinking about the practicalities of sustainability. Me and Aster are doing the Practical Sustainability course. And this is our roundhouse building practical lesson. Which we are obviously very much involved in. These are ex-battery hens. We need to turn it right around because here’s the first one so we’ve got the wrong angle. We’re making notches or grooves the next rafter will fit. Thus. Simon’s attaching it to one of the poles of the tripod. In theory you measure from that bit of string to the cross on the first rafter. And then tie it when it’s half of the distance we want. So we went for a metre. so it’s 50cm, yes? Welcome Rafter! Angels of green building be with us. If you look at the gap between the last one and the first one now. You can see already that it’s going to be handle-able I think, because that first one is already higher than number 9 and we’ve got 4 more to go and we’ve got space to get them in so as long as this tripod here isn’t too much in the way or the Charlie stick itself I think we should get away with it. I think it’s working out ok. We’ve got the last one in. Now we can let down the first one onto the last one. And that involves a bit of dodgyness. The most likely thing that goes wrong at this stage is as they pull against the string he’s tied one of the pieces of string snaps and the whole thing goes a bit out of kilter. But he’s got nails there, and everything else is tied, so it’s not actually a serious danger in my opinion. We’ve got plenty of overlap. And so we’re going to let down the Charlie, bit by bit. And hope that the notch in the first one will meet the last one. If we’re lucky, we’ll get a nice circle out of it. He’s putting a nail there in advance to try and contain it. Yay! Tie the first to the last. and also the last to that one again. So it is now free-standing. So you can remove the Charlie now. You can take him to bits. Well done. Totally on the case. 3D. You need good 3D sense for that. You have to tune into it. Well done. Thank you all for a really groovy day. See you in the morning. Thanks to the Angels for being with us and for this to be up. Great!. Well done.