The first half-buried house I noticed on purpose was on the road between Tintagel and Boscastle, in west Cornwall. I had been walking for an hour without seeing one and then, suddenly, I had been walking past one for several minutes without realising. It announced itself only by a chimney and a slate path. The roof was a slope of grass, thirty degrees off the hill behind it, and the windows turned away from the road and out toward the sea. From a hundred metres back the cottage was indistinguishable from a fold in the field. From three metres away it was a house — small, deliberate, mostly stone — that had decided not to argue with the weather.
That feeling, of a building that has chosen not to declare itself, is what I want to write about. The half-buried cottage is the residential type that interests me most at the moment, and not for the reasons the magazines tend to cite. It is not, primarily, about energy performance. It is not, primarily, about being off-grid or passive — although, almost as a matter of accident, these houses tend to be both. It is about a particular ethic of presence: a willingness to be smaller than the landscape.
§ I.What the earth does for free.
The structural physics of a bermed house are, in fact, embarrassingly simple. Soil at one metre below grade sits, in most of the temperate world, somewhere between eight and twelve degrees Celsius for the entire year. It does not care that it is January or July. If your back wall is in direct contact with that soil — through a properly drained, properly waterproofed concrete or rammed-earth skin — you have, before you have hung a single radiator, halved the thermal load of the room. The earth is doing the work that, in a conventional house, the boiler is asked to do twice a day.
We tend to dramatise this. We build glass-fronted, off-grid retreats and put them on the cover of Dezeen and call them radical. I am not against the glass front; some of my favourite houses have them. But the actual radicalism of the bermed cottage is older than any contemporary movement. The Dartmoor longhouse, the Welsh crog-loft, the Faroese turf-roofed farm, the Icelandic torfbær, the prairie sod-house — all of them are versions of the same idea, which is that the easiest way to keep a small building warm is to put part of it underground and let the planet regulate the rest.
§ II.Privacy is not retreat.
A client, last year, asked us to design him a retreat. He used the word four times in the first meeting. He wanted, he said, somewhere he could disappear. We took him to see a bermed house an hour north of the studio, built into a slope above the Hudson by an architect we admire, and afterwards he was quieter. On the drive back he said, accurately I think: that's not a retreat. That's a house that knows where it is.
The half-buried cottage is, for me, the type that draws the cleanest line between privacy and retreat. A retreat hides. A private house just declines to broadcast. The bermed house does the second of these without ever pretending to do the first. From the road you see slate, grass, possibly a chimney. From the inside you see, almost always, a long horizontal opening calibrated to a single view — the valley, the sea, the line of trees at the boundary of the meadow. The privacy is incidental to the orientation. The orientation is the point.
A building that hides is performing. A building that has decided not to be the loudest thing in the room is just paying attention.
There is, I think, a quiet political content in this. We are at a moment in residential architecture in which detached single-family houses, particularly in beautiful landscapes, have to answer for themselves. They have to answer to the planning authorities, to the watershed, to the neighbours who can see them from a mile away. The half-buried cottage answers all three of these honestly. It cannot dominate the ridgeline because it is not on the ridgeline. It cannot drink up the heating budget because it has already given most of that budget to the soil.
§ III.Detail notes for the studio.
We have one bermed scheme on the boards at the moment — a small weekend house, two bedrooms, on a sloped meadow above the Beaverkill in the Catskills. It is not yet at the stage where I am ready to publish it, but the construction logic is worth saying out loud, because most of the failures in bermed houses come from the same three places.
The first is drainage. Earth-contact concrete does not fail because it cannot bear a load; it fails because somebody let groundwater pool against it for ten years. A bermed house is a drainage detail with a roof. The geotextile, the French drain, the gravel apron, the slope of the soil away from the wall — these are the drawings I review three times before a single bag of cement is opened.
The second is the roof line. A grass roof that meets a stone wall in a sharp horizontal joint will fail at that joint, every time. The vernacular knows this; the vernacular runs the soil up over the wall in a continuous fold. A contemporary bermed house has to either commit to that detail honestly or use a contrasting cap-flashing — a slate course, a copper drip — that makes the change of material legible. Faking continuity with sealants is a five-year solution.
The third is the front face. The half of the house that is not in the ground has to do all of the architectural work of the house — light, view, ventilation, the symbolic business of where you put the door. We have, I think, a tendency to over-glaze it, because we are anxious about the dimness of the rear rooms. This is misdiagnosed. The rear rooms in a bermed house should be dim. They are sleeping rooms, study rooms, places the body wants in a thunderstorm. Light them with the slot clerestory and the single deep window, not with a continuous wall of glass.
§ IV.What it teaches us about the rest.
The reason I keep coming back to the half-buried cottage — even when the studio is working on a brownstone in Cobble Hill, or a retail interior on the Lower East Side — is that it teaches a habit of orientation toward the existing that transfers. The same instinct that makes you set a Cornish cottage against the prevailing wind makes you set a Brooklyn parlour floor against its own one good window. The same instinct that makes you let the soil do the heating makes you let the nineteenth-century plaster do the acoustic work it has already been doing for a century.
Most architecture, most of the time, is the act of deciding what not to add. The half-buried cottage just makes that decision very legible. It is, in its way, an essay on restraint that has been written, slowly, by the weather, for several thousand years. We are still trying to read it.