Monday 29 November 2010

Site specific low cost housing for a windy site

Part of the issue of building housing on the site we're considering is the wind speed, which is high. I imagine we're all going to want homes which don't take a lot of energy to heat, and the wind-chill effect on exposed walls is going to be considerable. The parts of the site which are most exposed to the wind are also the sunniest – the southern and western slopes. Of course, one can insulate, and straw bales are worth considering.
However the alternative, given that we have reasonably steep slopes, is to get down out of the wind. And if you do that you also lessen the landscape impact of the dwelling dramatically.
We all need structures which are low cost and simple to erect (since we're likely to be using mostly our own labour).
My suggested response to this set of problems is to dig into the hillside, build structure, and backfill over it. The modules I'm suggesting are hexagonal, simply because I like the shapes sculpturally – cross vaults might be more practical, because you'd get a rectangular floor plan, but you'd also end up with straight lines on the hillside which would be more visually intrusive. One advantage of the hexagonal module is that you can put the modules together to follow the contour in a more flexible way. The approximate size of the module is 2.4 metres per side, or 4.8 metres diameter. This gives a floor area of 15 square metres (about 150 square feet) per module.
Note that I'm guessing that this structure would be low cost – I haven't had it costed by anyone remotely qualified to do so.


This proposal is mainly concrete. I would have preferred timber but am not confident I can design in timber in a way that would be durable and maintainable under ground. As such there's a substantial energy cost in making the cement. There's also embodied energy in vermiculite used as filler. Overall, though, it isn't hugely much concrete – probably not as much per living unit as in a conventional block of flats. Because there's no wind exposure, and all the exposed sides are oriented towards the sun, it should have adequate passive heating even in winter; any supplementary space heating needed, water heating and cooking can be provided by a stove burning fuelwood grown on site. Large opening windows allow for cooling in summer.

Visual impact

One of the main objectives of this design is to minimise visual impact on the landscape. Because the terrace retaining wall is half the height of exposed sides of the structure, and because the slope above the structure matches the slope below the structure, from upslope or downslope there will be very little to see until you're very close.
From further away there will be a horizontal visible feature in the slope, but because all the curves are organic it shouldn't look too visually intrusive or artificial.


The building is constructed of four different concrete elements, as follows:

Dome segment

Obviously, six dome segments are needed for each dome. These will be the heaviest elements, and most difficult to move; it would be preferable to cast them in place, by erecting the pillars first and then erecting the former where the dome segment is to be located. Even if the segments are cast in place, however, they probably need to be separate segments rather than a single monolithic dome because of expansion issues. The cross section of the dome is probably a catenary, rather than an arc.


One pillar at each corner of each dome, obviously. Hollow pillars – even if they do not contain drains – will be lighter and easier to install without being substantially weaker, so the core of the pillar element might be a spun concrete pipe section. The pillars need only be two metres tall because the natural shape of the edge of the dome will in any case form a slight arch.

Flying Buttress

Domes have thrust: they want to fall down, and in doing so they push out radially at their base. This thrust has to be resolved. In the unexposed edges of the dome (which, when building into the hillside, is most of them) that thrust is resolved simply by backfilling the soil. On the exposed edges – which we want, because we want light an air into the dwelling – the nature of hexagonal cells is that some corners are convex, and some are concave. How many of which you have depends on the shape of the site. On each convex corner you need something to take the thrust of the dome, and my choice it to have a flying buttress. This would span a terrace in front of the building and transfer load to its retaining wall.


The eve element is essentially just cosmetic; it joins adjacent flying buttress or eve elements into a continuous organic curve, again helping to reduce straight lines in the landscape. The eve units are designed so that although they show a fair curve on the outside they have a horizontal on the inside, so that ordinary standard patio door double glazed units can be used in all the exposed sides.

Building method

Again, this needs to be run past people with more experience than I have. Preventing damp ingress into the dwelling needs to be thought about carefully.

Dig back into the hillside

Strip off the turf and retain it. With a mechanical digger, dig back into the hillside; obviously, choose a site with contours which minimise the amount of digging that needs to be done. Reserve the soil removed, we'll need it later. Reserve topsoil separately from subsoil. The rock on site is part of the Kirkcudbright Shales and is probably soft enough to break up with a digger, is actual rock needs to be removed.

Lay drains

Lay drains under the site from uphill to downhill; these will later be joined to lateral collectors on the uphill side to reduce water pressure uphill. Rainwater drains can simply discharge downslope – they're only carrying water which would naturally drain down the slope anyway. A separate soil drain needs to lead to some suitable treatment.

Level platform

Level roughly with hardcore; finish with sand.

Pour slab

Taking one hexagonal module at a time, lay a waterproof membrane on the sand with at least 2.5 metres overlap on the uphill side, shutter the hexagon, and pour a self-levelling concrete. I need advice on the thickness of the slab. It almost certainly needs to be thicker under the pillars.

Erect pillars

It's possible that the pillars should be hollow with a drain down the centre of each one, linked into the under-slab drains, to move water from over the structure to under it. However, there's an issue about how to achieve a watertight seal at the top of these, so unless someone else can solve it that isn't part of the plan. In any case Pete suggests that the pillars should be founded on concrete piles going down to bedrock.

Erect uphill walls

Between each pair of pillars on sides which will be backfilled, erect a breeze block wall.

Erect terrace retaining wall

In front of the structure along edges that are to be exposed, erect a dry-stane dyke about a metre high and about two to three metres away from the structure, with footings in the right places for the flying buttresses. The exact width of the terrace at any point should be chosen so that when the structure is complete and backfilled, the slope above the building should continue as a fair curve in the slope below the building.

Part-backfill the uphill side

Bring the excess waterproof membrane laid down when pouring the slab up the sides of the newly erected uphill walls. Backfill, installing lateral drains as you go. At this stage, backfill to about 50cm below the tops of the walls.

Erect flying buttresses, eves and (possibly) lintel arches

In order to resolve the thrust on the domes, the flying buttresses and eves must be in place before the domes are cast – otherwise they'll just fall down as soon as the armature is removed. However, not all the pillars are supported against thrust in all the necessary directions until all the domes are up – to some extent, once completed the domes will support one another. One solution to this would be to cast lintels between each pair of adjacent pillars. If this solution is chosen, they must be installed at this stage. Alternative solutions are
  • Embed a tensile steel reinforcing belt as low as possible in each dome;
  • Construct separate armatures for each dome and leave them in place until all domes are cast and cured.

Erect domes

For each dome that is erected, a wooden armature needs to be erected to support the segments until all are in place. This armature needs to be supported on wedges so that when the dome is complete, the wedges can be driven out and the armature disassembled and moved to the next dome. Before the armature is removed, the flying buttress and eve elements which support the exposed edges of the structure must be installed.
Because of the steepness of the lower slopes of the dome, some though is needed on how to prevent the concrete from slumping before it is cured. Some upper surface shuttering may be required, and thought needs to be given to how to secure this. Also, it will probably be necessary to erect some sort of gantry or scaffold in order to apply and smooth concrete over the centres of the dome – because certainly that will be out of reach from the edges while the concrete is not set.

Fit chimney outer

Cut hole(s) for the chimney(s) in the appropriate place(s) in the domes (or, preferably, leave them when casting). Install vertical concrete pipe over the hole to the final ground level.

Fill valleys between the domes

On a settled, dry day, or better still on the first day of a run of settled dry days, fill the valleys between the domes with a lightweight inorganic filler material such as vermiculite. The object of this exercise is simply so that from every point on the structure, when the upper membrane is in place water will naturally drain to one edge and will not pool; the valleys do not have to be completely filled by any means. This doesn't need to be done if a watertight means of joining the upper membrane to drains running down internal pillars can be found.

Lay upper membrane

Lay a waterproof membrane over the whole structure, overlapping the uphill sides by half a metre. Fold this overlap down over the overlap of the lower membrane. Sealing around the chimney and any internal pillar drains is an issue I haven't solved, but I imagine suitable mastics may be available.


Backfill over the whole structure, first with subsoil, then with topsoil. Contour the backfill to form a natural slope. Turf over. Similarly backfill against the retaining wall on the downslope side.

Install glazing

Ordinary standard double glazed 'patio door' units are installed into the exposed sides.

Fit out interior

To taste.

Rough costings

The following costings are preliminary, and are based on concrete costs only, with no allowance for levelling the platform, fitting drains, services, labour and so on; it's mainly to cost the bits of the structure I don't have a good feel for. This looks startlingly low – as if I've got something wrong by a factor of ten. I hope not!

Sousterran: quantities and mass

Concrete option




Unit Price per sq m
Mass of 1 cubic metre of concrete 2400 Kg

Bituthene 3000

20 metre roll £163 £9.03
Mass of 1 cubic metre of soil 1700 Kg

Styrodur 3035CS, 30mm

14 sheets at 1250x600mm £70 £6.67
Price of 1 cubic metre of concrete 100 Pounds sterling

Styrodur 3035CS, 60mm

7 sheets at 1250x600mm £70 £13.33
Price of 1 8x4 sheet 15mm exterior ply 40 Pounds sterling

Total, with 30mm

Price of 1 sq metre concrete blockwork 10 Pounds sterling

Total, with 60mm

Dome radius (long axis) 2.4 metres

Area of dome floor 14.98 square metres

Area of dome surface 36.19 square metres

Number of wall panels 11 at 4.8 sq metres

Elements Area sq m Thickness m Volume cu m Mass tons Concrete Cost Cladding cost Number of Total cost Total mass Shuttering sheets Shuttering cost
Floor 104.83 0.1 10.48 25.16 £1,048 £399 1 £1,448 25.16 1 £40
Dome 36.19 0.1 3.62 8.69 £362 £809 4 £4,685 34.74 42 £1,680
Dome segment 6.03 0.1 0.6 1.45 £60
34.74 7


0.5 1.2 £50
17 £850 20.4 6 £240

1 2.4 £100
5 £500 12 4 £160
Flying buttress

2 4.8 £200
4 £800 19.2 6 £240
Wall 4.8 0.1 0.48 1.15 £48 £75 11 £1,357 12.67 0

Overburden 104.83 0.2 20.97 35.64 £0
1 £0 35.64 0 £0


50 £9,639 194.56
Total, cost


Thursday 18 November 2010

Practicalities of 'affordable' housing

This document attempts to address how in practice we would implement an affordable housing policy if we choose to do so.

The company – that is to say us together as a corporate entity – will buy the farm and resell the land to each of us; in reselling the land it can add a burden. But that would be a burden on the land, not on the dwellings, and I don't think that's what we want. We could probably sell the land with a condition of sale that any dwellings built on it would be subject to the burden, but I'm not certain exactly how we're do this – we need to check with a lawyer.

Rural housing burden

A particular form of burden that is available to us is the 'rural housing burden', established in section 43 of the Title Conditions (Scotland) Act 20031. To use this we'd have either to apply for the company to be registered as a 'rural housing body' or to work with an organisation already designated as a 'rural housing body'. It would be better if at all possible if we were registered.

The rural housing burden gives the 'rural housing body' – that is, the Standing Stone company – a right of pre-emption; which means, as I understand it, that the company has 42 days from the day you decide to sell to decide whether it will buy. Remember that the company is essentially just ourselves, taking decisions on a one member one vote basis; we could give the company in its constitution (memorandum and articles) a clause which says that a decision to buy a dwelling requires a general meeting, not just a decision by directors.

Under section 84 of the act, if the company does not decide to buy within 42 days, the 'rural housing burden' is automatically extinguished, and you can sell your dwelling on the open market.

I'm not clear from my reading of the act whether the company would have the right to pre-empt at a particular price (the 'just price' or 'affordable price' as discussed in my previous document); we might need an additional legal agreement to assert this – if that's what we want to do.

To what should the burden apply?

We've discussed in meetings the undesirability of people building a dwelling on a holding, then selling the dwelling and land separately, allowing someone to build a new dwelling on the remainder of the land, and so on, until we have a housing estate.

There are clearly two options:
  1. The burden could apply to the dwelling and curtilage only
  2. The burden could apply to the holding
But we need to be aware that people may want to sell parcels of land rather than their whole holding, and, within the context of company, we almost certainly want to allow that. If we don't apply the burden to the whole holding, we can't prevent people selling parcels of land to surrounding landowners, and we might want strongly not to allow that!

I'm not clear from the act whether a 'rural housing burden' can apply to a whole croft, or only to the dwelling; that's another thing we need to clarify.

Can we use other burdens?

The whole purpose of the 2003 act seems to be to limit the burdens that can be placed on housing. Very few are allowed. There is a form of burden called a 'community burden', but its purpose seems to be limited to the appointment of a managing agent, for example for a block of flats. A community burden does not appear to give the right to pre-empt a sale. So it seems to me that the rural housing burden is the only burden we can use.

Alternative price cap models

I can envisage four mechanisms for establishing a price at which the company can pre-empt a sale.


It does not seem to me that it makes sense to apply a cap to the price of the land part of the holding. All land is to some extent subject to speculative pricing, and in particular the price of agricultural land is artificially inflated by public subsidies to farming, but there's little we can do about that: land has a commercial value, and an incoming holder can in principal try to make a commercial return on it – if they choose. So it seems sensible simply for the company to have the land valued as commercial agricultural land, and then pay that amount for the land element of the holding.

The existing farmhouse

It isn't reasonable to apply any price cap formula with the possible exception the 'just price' to the existing farmhouse. Ruth and Gav will have to pay the open market rate for the house (unless we jointly decide to subsidise her, which is possible but hasn't been discussed); having paid the open marked rate, it isn't fair to expect her to resell at a capped rate.

If we were to bring Ruth and Gav into the capped rate scheme, we would have to lower the price they pay for the farmhouse to £105,000 – which means that the ten other holdings would each have to put £3,500 into subsidising Ruth and Gav. That isn't impossible and would make things feel fairer in the long run, since everyone would then be subject to the same cap – but it adds complexity and is yet another thing to discuss and get right, and we have limited time.

The remainder of this discussion applies to the dwelling part of the holding, for new build dwellings.

Match price

The first model would be that the seller seeks a buyer on the open market and agrees a price; the company then has the right to match that price. I can see no advantage to the company in this; it would effectively mean allowing the price to rip with the speculative rise in house prices generally, and the company would in effect only be able to purchase properties if it could attract wealthy new members. I don't believe this is what we want.

'Affordable' price

The affordable price model uses a function simply based on local average wages to establish the price of a dwelling, without taking into account the actual amount of effort that has gone into that dwelling, or how well designed, spacious or well built it is. Of course, the 'affordable price' would be literally a ceiling, but in practice I think it would be very hard for the company to offer less than the ceiling price to a member wishing to sell.

This means that a member who had worked very hard to create a really nice house would get exactly the same price as someone who had done the minimum to get past building warrant, which seems a little unfair; but it's worth bearing in mind that the 'affordable' price is still likely to be higher than the 'just' price, since we're none of us very rich and therefore the 'just' price is likely in almost all cases to end up below the affordable price.

'Just' price

As I outlined in my previous document, the 'just' price seeks to represent what has actually been invested – including sweat equity, investment of your own labour – with an adjustment for inflation, so you can always get out the inflation-adjusted amount you put in. This is my preferred model, because it seems to me fairer – but it has a number of problems, and, essentially, it's only fairer if we're all honest. If a person claims a lot more 'sweat equity' hours than he or she has actually put in, the 'just' price is inflated. Also, keeping an accounting of what has been truly been invested in bought materials is also an issue, and could be manipulated.

'Reasonable cost' price

The 'reasonable cost' price is the price I described in 'just price revisited' in my previous document. It uses a formula based on the floor area of the dwelling in square metres, multiplied by an arbitrary assumed cost per square metre for which a dwelling could be built. This means that if you use marble staircases and solid gold taps, the 'reasonable cost' price will be lower than the 'just' price, and you may not recover your costs.

But, provided we agree a reasonable assumed cost – £1,200 seems a commonly cited value – then the 'reasonable cost' price will for most of us be about the same as or higher than the 'just' price.

Hybrid schemes

Note, of course, that to get the political support I believe we need in order to get planning permission, it will be greatly to our advantage to be able to talk about 'affordable price'. To do this, we could simply accept the 'affordable' price – which is likely to allow us all to make a significant profit. Or we could chose to use a hybrid scheme which said, for example, that the company will buy at either the 'affordable' price of the 'reasonable cost' price, whichever is the lower.

The 42 day rule

The 42 day rule is in the legislation and we can't vary it. Given that if the company fails to agree to buy within 42 days of being notified that the holding is for sale the burden ceases, we need to make an effort to ensure the company can buy – which means, we need to keep a register of people who are seriously interested in becoming members (and whom we would welcome as members).
What should never happen – and we should write a clause into the memorandum and articles to prevent this happening – is that the company buy someone's holding at the capped value and then sell it at the open market value. The company must resell for the amount for which it bought, with some allowance for fees. Obviously, in most cases it will probably be best for the company to allow the seller to sell to the new member directly, but at the price at which the company could pre-empt.

Wednesday 17 November 2010

A Just Price for housing

Standing Stone: reasons for adopting a 'just price' for housing

We live in a late capitalist society in which democratic politicians have deliberately stoked a speculative bubble in housing prices, because most voters are property owners and spiralling house prices mean that those who are already on the housing ladder feel richer. The consequence of this is that, over the country as a whole, house prices are already beyond the reach of many folk on ordinary wages. Along the Solway coast, the pretty villages have a price premium because they are attractive and pleasant places to live, but local wages are depressed. This means that folk working in the local economy cannot buy houses locally – unless they have inherited wealth.

So begins a process of clearance which is just as socially corrosive as the clearances of the eighteenth century, when the landowners enclosed land which had traditionally been common. The reaction, then, here in Galloway, was of a violent revolt by the country folk, throwing down the walls of the new enclosures and burning barns. Now, here in Auchencairn, I think the Caldows and Helen Sankey are the only people born in the village who still live on the main street (Geordie Milligan lives on Spout Row). Every other house is owned by incomers, and the native population has been effectively cleared across the burn into the bantustan of social housing. We have a very nearly complete ethnic segregation, with those who live in the old village now overwhelmingly rich and English, and the Crescent overwhelmingly poor and Scots.

It wasn't always like this. The three houses across the street for me, when last sold in the 1950s, were bought for less than two hundred and fifty pounds for all three. When I bought my first flat in the village, I paid four thousand pounds. Now, the only property for sale in the village under a hundred thousand pounds is Monty's flat – which is tiny.

Unless ordinary people without inherited wealth are able to afford to own houses in this area on wages earned in this area, the social dislocation and, effectively, ethnic cleansing is only going to get worse. Ultimately, that must lead to unrest.

Applying this to Standing Stone

None of this is the fault of anyone in the Standing Stone project. It is a consequence of political and economic forces which are far bigger than us.

However, if we do get planning permission to build new dwellings on the Standing Stone site, the market value of those dwellings when they are complete will be very much greater than what they cost to build. If we don't cap the resale price, then we are effectively giving one another a speculators' charter, and we risk the site rapidly developing into yet another rich incomers' enclave. We risk this both because the speculative opportunity will suck in spivs, and because your actual people – the sort of folk we would choose to live among, that we think in developing the idea that we are choosing to live among – simply won't be able to afford to buy into it.

People have objected – very reasonably – that they need to be able to get their investment out again. And it is true that if the housing market continues to spiral madly out of control, then if we put a cap on resale prices of dwellings at Standing Stone then people may not be able to leave, because the capped price will not realise enough money to buy a replacement property on the open market. These are real and reasonable issues.

The just price

Clearly if we are to derive a formula for a 'just price' for a dwelling, that formula needs to represent the investment which has been put in – including investment as 'sweat equity', our own labour which we've expended in creating the dwelling.

Furthermore, we need to notionally detach the value of the land from the value of the dwelling. The 'croft' part of the holding – without planning permission – has a value as agricultural land. So the capped value of a holding, if we choose to adopt a 'just price' cap, is the market value of the agricultural land plus the capped value of the dwelling, and (irrespective of what DGSHT's policy says) clearly the 'just price' cannot be less than the total amount reasonably invested. If Ruth has invested a sum in the farmhouse, then she must be able to realise at least that sum if at some time in the future she needs to sell. To expect her to accept less is just unreasonable.

But at the other end of the scale I'm expecting to spend less than £40,000 cash (and a lot of work) on structure. My dwelling, at the end of that, will have one bedroom, rather than the three or four that the farmhouse has, but as a modern designer structure with a nice view it's open market value isn't going to be a lot less. If I'm spending £55,000 on ten acres of land, then the pro-rata cost of the half-acre of that which forms the curtilage of the dwelling is about £2,500. For simplicity say I spend £7,500 on design fees and contractors, and value six months of my full-time equivalent labour at £10,000, then the investment cost of my dwelling is

Fees and contractors
Sweat equity

Should I be allowed to sell this dwelling which has cost me £60,000 for £120,000? Why? What justifies me making such a speculative profit?

The affordable price

The average annual wage in Dumfries and Galloway is around £20,000. This means that the cost price of my one bedroom dwelling is three times the income of a single wage earner – a multiplier which is certainly acceptable to mortgage lenders. Actually, DGSCHT consider a multiplier of 3.5 times average annual wage to be reasonable. And on a two bedroom dwelling, that's 3.5 times not the income of one wage earner, but the income of 1.5 wage earners – a household with one person working full time and one person working part time. So the affordable price of my one-bedroom dwelling would be £75,000, and the affordable price of a two or three bedroom dwelling would be £105,000.

Now, OK, in aiming for a £40,000 structure cost I'm aiming to build a structure which is affordable to me, so it has to be 'affordable' – I'm too old to take on new debt. But a cost of £1,200 per square metre seems a commonly quoted value these days, so (allowing the same figures for land value of the curtilage and for fees as in my example) you have £95,000 to spend on structure of two to three bedrooms (including sweat equity), which builds you 80 square metres of reasonable quality structure, which is equivalent to six rooms each 12 foot by 12 foot.

Thus it seems to me that it is possible to build new dwellings on the site such that the cost is lower than the 'affordable price'. Furthermore, knowing what I do of the group, all of us are going to have to build dwellings which cost less than the 'affordable price', simply because none of us are rich.

The just price revisited

This doesn't solve the Ruth conundrum, of course, because she's having to buy at full market rate and cannot be expected to take a hit to sell at an 'affordable price'.

So we need a formula which I think is something like this:
value of the land part of the holding
plus reasonable investment cost of dwelling
plus 2% per annum compound interest on the reasonable investment cost of the dwelling
value of the land is the agricultural value of the land as assessed by a qualified surveyor appointed by the Company
reasonable investment cost is for new builds and for the byre units an agreed multiple on the internal area of the dwelling in square metres, I'd suggest £1,200; for the existing dwelling, the price actually paid (including essential renovations).

This gives us a 'just price' which for all new units is likely to be lower than or equal to the 'affordable price' as seen by DGSCHT.

Non-idealistic argument for a just price formula

The arguments I advanced at the head of this document for a just price for housing are idealistic; they represent a rejection of the market in favour of enhancing social cohesion and abstract 'fairness'. I believe that most of us do have a degree of idealism, but I acknowledge that the exact degree varies.
However, bear in mind that getting planning permission for ten new dwellings on this site is a very big ask. It is precisely the 'sporadic development in the countryside' that the council has policy to prevent. We're going to have to do a lot of special pleading and special argument. If we fail to get planning permission, we're most of us going to have had a significant share of all our capital tied up for at least two years in land, with nowhere to live. And although it's probable that if it all goes pear shaped we can resell the land for the money invested, that isn't guaranteed.

So we need all the help we can get. We can get a certain amount of political if we're able to play the 'green' card, the 'low impact' card (but I'm not certain I can achieve low impact in my budget, and I suspect other people may be the same; concrete is cheap stuff). One card that we know we can play, though, is 'affordable housing'. And, we already know that if we play the affordable housing card, we will get not insignificant help from DGSCHT.

In summary, if we cap resale at an 'affordable' value, we will be able to recover the investment made in dwellings (provided we're don't built using solid gold taps and marble staircases), and we will get significant support which will significantly lower the risk involved in the project. That seems to me a substantial win for very little actual cost.

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