Planking the roof
Radial planking
Planking the roof of the cone poses interesting problems. You can plank a cone radially, and every plank is straight. My rafters run radially, but that doesn't have to be a problem; I could put short purlins between the rafters to fasten radial planks to. I can even envisage some rather pretty joinery for those purlins. It isn't impossible.
But every plank would have to be cut longitudinally — identically, so I could make a jig and it wouldn't be a big deal, but it's a significant job. More significantly, radial planking also would not strengthen and stiffen the roof, and I'm still concerned by my friend Pete's comment that the roof could be floppy in strong winds. The tensile bracing which Pete suggested and which I've shown in the last drawings will help, but...
Transport
One of the things I need to consider about the croft is moving around. Not moving me around, my feet or a bicycle do that. And for getting my groceries home, well, a bike or my feet or at worst a wheelbarrow will work. But while building my house I'm going to need to get a fair bit of building materials in, and once it's build I'm still going to need occasionally to move heavy or bulky stuff around.
The planners, of course, will not want a house which cannot be reached by road. But the planners are not me, and I do. At present, you can get a normal car over the hill to the croft... in dry weather. In normal weather, you can't — not because it will sink in, but because you can't get traction. The hill is too steep and you can't get grip.
So what are my options?
Longeaves
In my last essay I wrote of some unresolved issues in the singlespace design. In summary
- In a single space, a lavatory poses a problem;
- In my design as it stood, there was no external storage, for bicycles and firewood;
- The roof was potentially floppy, and thus vulnerable to damage in strong winds;
- Drainage on the north, uphill side, is problematic;
- The cone is an unnatural shape in the landscape, and half of it drains north, aggravating the drainage problem.
I've tried to address these issues in a new variant of the design, longeaves.
Shapes in the landscape, and aerodynamics
I've now discussed the singlespace design with a lot of people, and got useful feedback.
Several people have queried having the loo in the singlespace. Actually, that was never the plan. The plan is to have a cludgie about 50 metres away in the wood. However, this is a house to grow old in, and while it's one thing to go fifty metres into the wood on a warm summers day at fifty five, it may be a different thing on a cold winters night in twenty years time. So the design has to have an account of where an indoor water closet will go. And just at present it doesn't.
Another friend asked where I would put my bikes. Again, a very good question which this design really doesn't address. And it does need to. There's no point in having a dwelling which is almost invisible in the landscape if it's surrounded with ugly sheds.
Singlespace joinery detail
If the 'singlespace' design is to be built it has to be built quickly, and largely with my labour. Therefore there is not time (and not skill, either, really) for fine carpentry or elegant carving. Yet the structure is going to be exposed and needs to look good. What I'm considering in this essay is how simple carpentry can result in an elegant structure.
In my initial sketch of the structure I discovered that in order to avoid complex joins at the pillar heads, each pillar/ring beam assembly has to be rotated about the axis of the building by an odd multiple of the rafter spacing angle of the 'upstream' assembly. The rafter spacing of the inner ring is 15 degrees, and in both this drawing and its predecessor the second ring is offset by 15 degrees. The rafter spacing of the outer ring is 7.5 degrees; however, if you offset the outer ring by just 7.5 degrees it just looks odd and so in this drawing I've offset by 22.5 degrees.
Every pillar has exactly one rafter running through it, and the pillar is slotted to take the rafter. A single treenail positively locates the rafter to the pillar. Every pillar stands at the junction between two ring beam components. The ring beam components are joined with a mortice and tenon, and are then checked back into the pillar. Finally, they are lashed together round the back of the pillar, enabling a strong characterful joint. The ring beam components are notched slightly on upper and lower edges to positively locate the lashing. Each of the braces is checked into the pillar and fastened to it with two treenails. The brace is checked to accommodate the ring beam component it supports and fastened with two treenails; the joint might be a little more sophisticated than the one shown in this drawing, but I don't think it needs be.