Saturday 26 March 2011

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.

Which brings us to my objection: the isolated geometric cone, even if covered with turf, isn't a natural shape. Granted, as an architect friend has pointed out, there's nowhere you can see the cone against the sky - it will never be skylined, because of the rising ground behind it. But it still isn't a natural shape.

Also, significantly, rain which falls on the north half of the roof drains north. Of course there needs to be thoughtful drainage around the north half of the building, but still adding more water to the problem isn't helpful. From that point of view, building a gable from the apex of the roof north-east into the hillside would both make a (somewhat) more natural land shape and reduce the drainage problem.

However, you end up with an unlovely bastard structure, and this in a building in which the structure is necessarily exposed. I'm still somewhat in love with my twisted cone roof. And my architect friend feels that the flat planes of the gable roof will look as unnatural or more unnatural in the landscape than the cone.

So there are a series of unresolved problems with the design.

However, the worst of the problems is one which should have been obvious to me. That conical roof is going to generate a huge amount or aerodynamic lift, and mine is an exceptionally windy site. My architect friend, who pointed this out, said also that as I've designed it it is also floppy and will move in the wind. This isn't a crisis. He pointed out that I could brace the roof with tensile members, like a bicycle wheel. This resolves the floppyness - instead of moving like a jellyfish, it will move as a single rigid thing.


But, it will still lift. That lift has to be contained. Which means the pillars have to act as tensile members, and must transmit lift to the floor. Which means that footing pieces for the pillars have to be cast into the concrete slab foundation, in exactly the right places. So I have to get the exact positions right before I pour the slab, and I can't shift things even by a single centimetre once it's poured.

All these things are design problems. All of them have to be resolved. But none of them makes this design unusable. I shall continue to think.

Monday 21 March 2011

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.

The remaining rafters are laid on the ring beams and are checked in sufficiently to achieve a smooth,
fair, even cone to the roof. Because the rafters cross the ring beams at a range of angles each needs to be checked in individually on site - I don't think it would be wise to do this in the workshop and hope to get it right! the rafters obviously cross two ring beams, one at the upper end and one at the lower. At the upper end, the rafter is checked (although the sing beam might also be checked slightly); at the lower end, only the ring beam is checked.

Both ends of all the rafters are tapered upwards. The ends of the ring beam components are extended to a degree which is more than that strictly required for joint stability and again tapered. Exposed edges of rafters and ring beam components might be moulded with a router is there's time.

My intention at this stage is still to use plain ordinary manufactured patio door units for the front wall. Obviously these aren't designed to be fitted into this sort of structure, but they will save a great deal of complicated joinery and will just work, so I think it's worth using them and doing the necessary joinery to make them fit (and look reasonably good). I plan to put them immediately between the front pillars, inside the braces of the ring beam components, rather than either outside the pillars or inside the pillars. Obviously, between the tops of the patio door units and the roof there will be a series of complicated-shaped holes which will need to be made good with 60mm closed cell foam board faced with T&G boarding inside and out.

Finally - while this isn't strictly a joinery detail - both yesterday's drawing and todays show a polygonal wall for the back and sides of the structure. This isn't simply unnecessary - it will actually make fitting the waterproof membrane harder, because of the corners. So I now think a smooth circular wall with no corners would be preferable, and not greatly harder to build.

Sunday 20 March 2011


I'm revisiting the design of my proposed home yet again. Yes, I know this gets boring. But it's probably the biggest decision I'll make in the next ten years - I need to get it right.

I do like the four dome design - the design I've called 'sousterrain' - I've been working on over the past six months. It's scupltural and elegant. I think it would have elegant internal spaces. Because it's modular, you can add on modules; you can build only part of what you intend in the first phase, and live in that while you build more. Which I would need to do, since I can't afford to build it all in one phase, either in money or (probably) in time.

It's also very challenging for the policy driven, risk averse, conventional planning authorities; but frankly anything I design or want to live in will be, so that's almost a non-issue.

Food miles

However, there are a number of arguments against the sousterrain design. The first is 'food miles'.

I came up with two possible constructions, one of which was engineered plywood, the other of which was concrete elements cast in engineered plywood moulds. Plywood is a wonderful engineering material from which you can make elegant, strong, light structures. But it is mostly made from rainforest timber and one really has no assurance that the forest is sustainably managed. And it's been shipped half way round the world. It's also quite an expensive material - the four dome design in plywood came out at £20,000 for the shell structure alone, which probably makes it unaffordable to me. It's because it's an exotic, highly processed material that it's expensive.

Building the four dome design in concrete is much cheaper, despite the fact that a great deal of plywood would still be required for the moulds. Concrete is an amazingly cheap material, in financial terms. But it isn't cheap in energy terms. Making the cement for concrete embodies a huge amount of energy, with a very real carbon cost. And, in any case, it isn't made locally - from the point of view of Galloway it is again an exotic material, one which is shipped in.

I've been reading a lot of books about dwellings written by hippies lately. Mystics. People who feel that there is inherent merit in building in the stuff of the landscape in which they build - in wood and stone from the site itself. It's a romantic idea. But, beyond that, it's how most houses were built prior to our parents' generation; and, in all likelihood, how most houses will be built after our childrens'. In actuality, I could build with the materials of my own croft - obviously I could, people have been building dwellings in Galloway for four thousand years. But I am, although a hippie, a pragmatist, I hope, not a mystic. I could take the timber to build from my own wood. There is (easily) enough timber there - even for an all-timber structure.

Next, I could build the masonry parts of my building from field stone, as the people of Galloway have since the bronze age. On Standingstone farm, Auchencairn, I'm not short of stone. Now that really is practical - the embodied energy is significantly lower than building in concrete, and the stone costs me nothing except labour. I really could do it. Of course, I would still have to use cement or lime mortar, so the masonry isn't 'free' either in financial or energy terms, but it could be done and it would be better.


The problem with using my own timber is that would take a year to season, and that means either I would be living in something temporary for the winter, or else burning my building money renting winter accommodation. And it would take milling, which would mean that either I would need to buy a mill (not cheap) or hire one of my friends who have mills to mill it for me. In practice I can buy timber of similar species and quality to my own timber for little more than the cost of using my own, and, provided I get planning permission, can build this year. But note - this is timber, not plywood. Plywood I don't have the ability to make.

The problem with using my own stone... The problem with using my own stone is that an underground or earth-sheltered dwelling in Galloway has to be very waterproof. Very. Of course, waterproof membranes are not native to Galloway, which is why Galloway people have historically not built earth sheltered dwellings. Traditional houses in Galloway did have high quality insulation in the form of thatch; and it's possible to insulate houses with wool, which also is produced in Galloway. But I do plan to use waterproof membranes, and the waterproof membranes I know how to use are designed to be stuck on smooth, flat surfaces. So I'm inclined just to use conventional concrete blockwork for my walls. Yes, it's embodied energy and it's an exotic material. But it's a heck of a lot quicker and easier and I end up with a reasonably smooth flat surface to which I can stick membranes which I know how to use. Outside that surface I'll use sheets of extruded (closed cell) polystyrene foam - another exotic material embodying energy - both as insulation and to protect the membrane from the soil. I'd already decided both those points when working on the four dome 'sousterrain' design. I don't need to revisit them.

After all, in the front of my dwelling I plan to use glass. It, too, is an exotic material, embodying a lot of energy, but I don't see many people too purist to use it!

The Single Space

OK, so, plywood I can't afford. Using a lot of concrete niggles at my eco-wannabe soul. And the costs of my designs - while not high, by the standards of modern housing - are hard to square with my budget. I need to rethink.

The shape which encloses the most area for the least edge - wall - is a circle. A circle is also the easiest shape to heat. And that takes me to yurts, about which I've been thinking a lot lately. Yurts are very simple and elegant structures. I've already decided that if I absolutely cannot get planning permission, a yurt is the way to go. Having slept in a yurt, I'm confident I could be comfortable in one. But it would be cramped. Even a large yurt of six metres diameter is only thirty square metres. Going up beyond about six metres you have a problem with the span of the rafters.

One American architect in one of the hippie books or websites I've read recently (I'm afraid I don't recall which one) solves this problem by arranging concentric yurt structures, with, essentially, intermediate tension rings supported by pillars. This is actually very similar to the design of round houses used by some native peoples of the south-eastern United States, and similar also to what has been inferred from post-hole evidence as the structure of a typical iron age dwelling in Britain.

A single circular space with the floor area of my four-dome structure - sixty square metres - would be slightly less than ten metres in diameter, or slightly less than five metres in radius. Which means two 2.5 metre rafters would span it with one intermediate tension ring.

A Subtle Twist

When I started thinking about this structure, I thought, as a western educated person, that naturally you'd run the two rafter sections coaxially, one in line with the other. But actually if you do that you get an incredibly complicated joint at the top of each pillar - a joint which it would be hard to make and harder to make strong. But if you offset the rings slightly, so that while each rafter is still radial to the structure it is no longer coaxial with the rafter up-roof from it, the whole structure becomes a lot easier to make, and also gains a subtle twist to the geometry which is elegant in a very unwestern way.

Internal Layout

I'm still - or, indeed, still more - resistant to the idea of internal partitions. I see this design as essentially a single space; I think its geometry demands that. But it's obvious that the stove needs to be at the centre, to provide even warmth. And it makes sense to put a (large) hot water tank also in the centre - since the hot water tank also forms part of the thermal mass which keeps the dwelling warm. A traditional yurt has two pillars supporting the ring into which the inner ends of the rafters fit; I've designed a triangle of three pillars. This triangle defines the 'warm core'; it contains the stove (facing south, towards the sun, and therefore the day side of the dwelling) and the water tank (behind it, to the north, in the night side). North of the warm core is the most shaded and most private space, so it makes sense to put the bed there.

It will be most welcoming if the floor between the entrance - the south, glass, wall - and the stove is largely clear. Kitchen preparation area is obviously needed near the stove, and should form one edge of this clear space. A dining area should also be near the stove and forms the other. Further back, the bath area needs a certain degree of privacy - not a great deal, since there are no near neighbours, but some. It makes sense to put this to the west, as there is some shelter from people approaching from the east. A work area needs protection from direct sunlight, which is hard on the eyes - but, at the same time, it's nice if there's a view. So it needs to be further back in the dwelling, and it makes sense to put it on the east.

What Doesn't Change

This is still a design to be built into the hollow I had already identified as the sousterrain site. It's still a design which will be earth sheltered - have earth covering the entire height of the north, east, and west sites; whose roof will be covered with turf; which will have 'patio door' sliding windows in its south wall, rather than a door as such. It's still a design which is intended to be inconspicuous in the landscape - although the low cone of the roof will be more obviously unnatural than the shapes you'd get from the four domes.

The Bottom Line

I started drawing this structure really as an experiment in exploring alternatives. What's startling, though, is how inexpensive it is. The materials cost of the shell works out at £6,020 - as against £11,999 for the four dome design in concrete, or £20,180.68 for the four dome design in plywood. Furthermore, while making the domes or the moulds for the four-dome design would need extremely careful finely detailed joinery, the 'singlespace' design is all simple carpentry. Unskilled people could actually help in building this. And, because it's simple, it could be built quickly - getting the shell completed in one summer season does not seem unreasonable. I'm now thinking of this design as my probable structure. Of course the verdammt planners won't like it any more than they would like the four dome design, so planning permission is still a major headache - but I don't think it's a worse headache, just something that has to be tackled.

Thursday 10 March 2011

The Plan

Julie asks, what's the plan?

The plan, above all else, is to continue to live in the hinterland of Auchencairn, without having the money it now takes to buy somewhere here. That applies to all of us. The first stage of the plan has been to group together and buy a farm. That's completed; we've done it. Ruth has been the animateur of this stage of the plan, and as her share of the deal, she's got the farmhouse. So she doesn't need to build anything.

For the rest of us, we do. We don't, at this stage, have planning permission with which to do it. We're a mixed group, but usefully mixed. Boy Alex is a tree surgeon and feller, and intends to establish a saw mill. He's (naturally) thinking about a timber framed house, with Alice, who is a multi-media artist mainly working with film. James is an electrical engineer with a special interest in wind generation; if I'm up to date with his plans he's planning something like an earthship for himself and Vicky, and their young family. Justine and Si run a business providing up-market accommodation - mostly in yurts which they make themselves - at music festivals; their plans are slightly longer term but they have been talking about a straw bale or cob house to live in; they will use their land as a campsite and perhaps run yoga courses. Finn is a blacksmith, and doesn't actually plan to live up at the farm; but he is planning to move his workshop. Godfrey is a shoemaker; his plan is for a craft workshop and gallery, and perhaps a cafe, in the existing byre building. He also plans to establish a market garden, although in the end it might be someone else who does that.

And then there's me. I don't really have any special skills, but I'm good at learning stuff and good at making things happen. I'm planning to build an earth-sheltered structure, mostly because I want to. The details, and the thinking about it, are in other essays on my blog. For the rest, I've bought seven acres of pasture and three of spruce plantation; I'm planning to plant some of my pasture with mixed native tree species to provide shelter (it's an extremely exposed, windy site). If I can get enough other people to share in the work I might keep a couple of milch cows on my pasture to provide milk for the farm; otherwise I'll probably buy a few weaner stirks each spring, and slaughter them in the autumn for beef. I'll also have a vegetable garden, although how good I'll be at making that work we'll see.

I'll need to generate my own electricity, because my croft is too far from the powerline for me to be able to afford to use mains; but fortunately there is no shortage of wind. We do fortunately have mains water, but if we didn't there are springs we could make use of - this is Galloway, after all!

My existing plantation should provide sufficient fuelwood indefinitely for my home, and I will progressively replant it with native species as I extract. But in addition, I share with everyone else in the 'commons', the land which we haven't allocated to anyone individually, and that includes 15 acres of woodland - mostly spruce - which will provide some construction timber and probably provides sufficient fuelwood indefinitely for everyone.

No-one's plan is to live exclusively off their land. We none of us have enough land for that. And we won't be operating the farm as a strictly commercial farm, more as a collection of crofts.

The extent to which we'll work as a community is still very much fluid, and will develop organically. In the short run, we're all broke and will have to help one another out with things. In the longer run, I'm sure things will develop. We're all nervous about the amount of organisation, meetings and time that goes into running existing communes like Laurieston Hall, but inevitably there will be many things which it will just be sensible to do communally. For example, we're currently discussing whether we should buy a communal digger.

All of which is to say, there isn't really a plan, beyond some broad brush strokes. We have a farm - in a startlingly beautiful (if windy) location. We have a bunch of interesting, capable people. We are going to live there (although that may take some robust negotiation with the planners). Stuff will happen.

It's an adventure, and the second phase - settling in - starts now.

Tuesday 8 March 2011

Clutching at straws

In my last essay I discussed the possibility of using wool as insulation. After all, as I said, we have wool. The problem with using wool as insulation in the walls is that it has no structural strength and is not weatherproof; it must be packed into structural, weatherproof boxes. The wool is virtually free, but the boxes come expensive.

Well, OK, we do have wool. But we also have straw (and a square baler to bale it). This year we're growing three acres of barley on my croft, and thirteen acres across the farm as a whole; and no-one else is going to be bidding for the straw, except as horse bedding. Straw bales provide both structure and insulation. Indeed, the first straw bale houses, on the north american prairie, also had turf roofs, so there's no doubt whatever that they can sustain the compressive load. The insulation values - tested, again, over a century of prairie winters - are very good.

In straw bale construction, you need, of course the bales. In order to tie them strongly together, you need a certain amount of steel rod - about two or three metres for each square metre of wall. And you need a rodent-proof render on both inside and out. On top and bottom you also need something rodent-proof; boards are possible, but so is render. All this is cheap - as cheap as or cheaper than concrete blocks.

The bales must of course be used after the harvest - so September - and must be laid and rendered dry. Dry weather is not guaranteeable in Galloway autumns, so there would be benefit in having the roof up first. Furthermore if the roof isn't up first, there isn't a lot of time to get it up before winter closes in. Of course, if the roof is to be up first it must be supported on pillars. Of course, those pillars could be temporary - my proposed roof structure is after all, as Pete objected, floppy, and so will accommodate a slight movement as the pillars are removed (provided that it is slight!).

All this begins to look very like a plan. It is cheap - actually the cheapest structure I've so far costed. It's also extremely 'green' - low energy, low carbon cost. I continue to assert that the zero carbon house is impossible to achieve - this one will have some sort of plastic membrane on the roof, and will have glass windows; furthermore a certain amount of cement and quicklime will be needed for foundations and render. But this is probably as close as it is possible to get. And it makes use of materials - timber, straw, wool - which we produce on site. I think I have a plan.


My parents rented the top cottage on Nether Hazelfield in 1965, when I was ten, and from that time I've always seen Auchencairn as home. Although my parents bought a house in Kirkcudbright in 1969, I returned to Auchencairn in 1977 to set up a pottery in the old mill. That business lasted until 1981, when Mrs Thatcher had her first recession and eight of the thirteen potteries in Dumfries and Galloway ceased trading, including mine. In 1982 I went away to University, and after graduating, worked as an academic in Artificial Intelligence for three years before becoming chairman of a spin-out company, attempting to market the products of our research. That company traded successfully until the recession of 1991, when it was wound up, and I returned to Auchencairn.

I've been here ever since. This is my home.

If I'm to stay here now, however, I need a home I can afford; and house prices in the village itself have become very silly, as more and more houses have become second homes or retirement homes for people who have not had to earn their living in Galloway's labour market. Consequently the Standingstone proposal has seemed to me a risk worth taking - it seems to be my best chance of staying in the valley. I appreciate that it is a risk.

If I'm to have a house here, it has to be small, cheap and simple. It has to be simple because I cannot afford to pay someone else to build it. It has to be cheap not only to build, but also to run, because the years in which I can continue to earn my living are limited. And, because it's a house to grow old in, it has to be durable enough not to need much maintenance in the next thirty years. All these things do not mean, however, that it shouldn't be well designed. On the contrary, each of them means that it should be well, and thoughtfully, designed. Building a house is something I'm almost certainly only ever going to do once; I want to get it right.

What I want is a house which vanishes into the landscape - one which, when natural planting has grown up around it for three or four years, a stranger can pass within fifty metres of and not know it's there. I want a house which is naturally warm, which doesn't take a lot of energy to heat. I want a house which is graceful and sculptural. I believe that this can all be done. More than that, I believe I can do it. I acknowledge that what I want isn't 'traditional' or 'vernacular' in Galloway, but it is nevertheless a designed repsonse to Galloway's particular geography and climate - and to my budget and needs.

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