One-room earth house
Sun-dried earth blocks on a stone plinth under a thatched roof, 4.0 × 3.6 m inside — the worked example for the building guide, from pegs in the ground to the first winter.
Build
Tier 1 · Neolithic
Shelter
Hard — heavy, slow, and every stage has to wait for the one before to dry
≈ 150–250 person-days over one dry season
Crew 4–6
Home: Dwellings, Level 1 · Foothold, level 1 of 5 in its track. Serves 1 step.
Every build on this site has hazards that injure or kill — quicklime, carbon monoxide, molten metal, collapsing ground. Read the safety notice before starting, and read this build's own failure modes below.
What it is and why this shape
A one-room house of sun-dried earth blocks (adobe) on a stone plinth, tied together at the top by a timber ring beam and covered with thatch. 4.00 × 3.60 m inside: 14.4 m² of floor, which is the Sphere humanitarian minimum for four people in a warm climate (3.5 m² each) and for three in a cold one (4.5–5.5 m² each). Build it as drawn once. The rules it follows are what you scale up from.
Every dimension answers one of three threats:
- Water from above. A 45° thatch with a 0.60 m overhang, so rain runs off before it soaks in and the drips land on gravel, not on the wall.
- Water from below. A stone footing, a plinth 0.40 m high with a slate damp-proof course, a floor 0.15 m above the outside ground, and ground graded away from the house. Earth walls fail at the base far more often than anywhere else.
- Earthquakes. The proportions come from the EERI/IAEE adobe tutorial (Blondet, Villa García, Brzev and Rubiños, 2nd edition, 2011), which draws on shake-table tests at the Catholic University of Peru. Walls at least 0.40 m thick, no taller than 6× their thickness (and never over 3.5 m), and no longer than 10× their thickness between corners or cross-walls. Openings no wider than 1.2 m, together no more than a third of any wall, and at least 1.2 m from corners and from each other. One storey, a light roof, and a continuous ring beam tying every wall top together.
The long walls sit exactly at the 10× limit. A longer room needs a cross-wall, not longer walls.
What is engineered and what is not. The earth-wall proportions follow the tutorial. The roof timber sizes are illustrative: what vernacular builders use to span 4 m under light thatch, not a calculated design. Where snow lies on roofs for weeks, or where you use a heavier covering than thatch, have the rafters and ties checked by calculation or by a builder who has seen the local roofs that failed. Do not build this on a floodplain, on made ground, or on a slope that has slipped before.
Cross-section, south to north
Fig 1
Earth / subsoilMasonry / brickTimberLoose fill / grainGravel / aggregateVoid / air
Plan
Fig 2
Earth / subsoilGravel / aggregateVoid / air
Wall base: where earth buildings fail
Fig 3
Earth / subsoilMasonry / brickGravel / aggregate
Ring beam at a corner
Fig 4
Earth / subsoilTimber
Keyed parts
| 1 | Thatch, 0.30 m thick, 45° pitch | Reed, straw or grass. The steep pitch sheds water before it soaks in. Thatch is also light, and a light roof is an earthquake rule. |
| 2 | Ridge pole, 120 mm | Runs 0.60 m past each gable so the thatch overhangs the gable walls too. |
| 3 | Rafters, 100 mm poles at 0.60 m | 18 × 4.0 m, paired into 9 couples. Sizes are illustrative for a 4 m span under thatch. |
| 4 | Tie beam, one per couple | Closes each couple into a triangle so the roof cannot spread and push the wall tops outward. Pegged or lashed to the ring beam. |
| 5 | Ring beam: two 75 × 75 mm rails | A ladder of two rails with cross pieces every 0.40 m, continuous round all four walls. It turns four walls into one box. |
| 6 | Adobe wall, 0.40 m | 40 × 40 × 10 cm blocks in running bond, with half-blocks at the ends. 2.20 m high above the plinth. |
| 7 | Lintel, bearing ≥ 0.30 m | Seasoned timber or stone, the full wall width, over every opening. |
| 8 | Mud plaster, two coats | Same soil as the blocks, with more sand and straw. It stops at the damp-proof course. |
| 9 | Damp-proof course | Two layers of slate, flat stone or tile, joints staggered, across the whole plinth top. |
| 10 | Stone plinth, 0.40 m above ground | Takes the rain splash and ground damp that would otherwise wash out the earth. |
| 11 | Stone footing, 0.60 m wide | In a trench 0.60 m deep, reaching firm subsoil and going below frost depth where frost reaches deeper. |
| 12 | Floor: rammed earth on gravel | Two 5 cm rammed layers on 0.15 m of clean gravel. The finished floor sits 0.15 m above the outside ground. |
| 13 | Gravel drip strip, 0.80 m | Under the eaves all round. Drips land on stone, not on mud that splashes the wall. |
| 14 | Cut-off drain, uphill side | A gravel-filled trench, 0.30 m wide, falling at least 1% to an outlet downhill. It catches water running toward the house. |
Specifications
| Floor area inside | 4.00 × 3.60 m = 14.4 m² | Sphere minimum: 3.5 m² a person in a warm climate, 4.5–5.5 m² in a cold one |
| External plan | 4.80 × 4.40 m | Long axis east–west |
| Wall thickness | 0.40 m | The earthquake minimum. One 40 × 40 cm block wide |
| Adobe height above plinth | 2.20 m | 5.5× the thickness. The limits are 6× and 3.5 m |
| Longest wall between corners | 4.00 m clear | Exactly 10× the thickness, the limit. A longer wall needs a cross-wall |
| Door | 0.90 × 1.90 m | East gable wall, 1.35 m from each corner |
| Window | 0.80 × 0.80 m | South wall, sill 1.15 m above the floor. In the southern hemisphere put it in the north wall |
| Vent | 0.40 × 0.40 m | High in the north wall, for cross-draught with the window |
| Footing | 0.60 wide × 0.60 m deep | Deeper to reach firm subsoil, and below the local frost depth |
| Plinth above ground | 0.40 m | Stone. The usual minimum is 0.30 m; this gives margin |
| Floor above outside ground | 0.15 m | On 0.15 m of clean gravel |
| Ring beam | 2 × 75 × 75 mm rails | Cross pieces every 0.40 m. Or 100–120 mm poles |
| Roof pitch | 45° | The minimum for thatch. 50° lasts longer |
| Eaves and verge overhang | 0.60 m | All four sides. 0.90 m or more in the wet tropics |
| Eaves height | ≈ 2.0 m | This is why the door is in the gable end |
| Ridge height | ≈ 5.3 m | To the top of the thatch |
| Ground fall away from walls | ≥ 5% for 3 m | 15 cm of fall in the first 3 m, all round |
Bill of materials
| Material | Quantity | Notes and substitutes |
|---|---|---|
| Subsoil, tested | ≈ 20–25 m³ dug | For the blocks, mortar, plaster and floor: about 35–40 t moved by hand, the biggest single job. Never topsoil. |
| Coarse sand, 0.5–5 mm | as the tests set | 0–3 parts of sand to 1 of soil in the mortar, per the sandwich test. The blocks often need less. |
| Straw, chopped 5–10 cm | ≈ 250–350 kg | Roughly 1% of the soil's weight. The real limit: as much as still lets the mix fill the mould corners. |
| Water | ≈ 6–8 m³ | About 1 L to every 4–5 kg of soil for moulding, plus curing and plaster. Sort out the supply before starting. |
| Adobe blocks, 40 × 40 × 10 cm | ≈ 800 | ≈ 720 laid plus 10% for breakage and tests. About 27 kg each. You make these. See step 1. |
| Half-blocks, 40 × 20 × 10 cm | ≈ 120 | For the bond at corners and beside openings. |
| Stone, footing and plinth | ≈ 7 m³ (≈ 18 t) | Flat-bedded pieces for faces and corners, rubble for the core. Makes ≈ 9.5 m³ of masonry. |
| Slate, flat stone or fired tile | ≈ 14 m² | Two layers over the 6.7 m² plinth top. Substitute: a salvaged bitumen or heavy plastic sheet. |
| Clean gravel or broken stone, 10–40 mm | ≈ 7 m³ | Floor 2.2 m³, drip strip 2.6 m³, drain 1.8 m³. No fines: fine material carries water upward. |
| Ring-beam rails, 75 × 75 mm | ≈ 38 m | Or 100–120 mm poles. Durable heartwood, bark off, seasoned. |
| Ring-beam cross pieces | ≈ 42 × 0.40 m | One every 0.40 m round the walls. |
| Lintels | 3: 1.50, 1.40, 1.00 m | The full wall width. For example, three 100 × 100 mm pieces side by side. Seasoned timber or stone. |
| Tie beams, 100–120 mm poles | 9 × 4.6 m | One per rafter couple. |
| Rafters, 100 mm poles | 18 × 4.0 m | At 0.60 m centres, 45°. |
| Ridge pole, 120 mm | 1 × 6.0 m | Overhangs each gable by 0.60 m. |
| Battens, 25–40 mm rods or split poles | ≈ 30 × 6.0 m | Across the rafters at the spacing your thatch needs, typically 0.20–0.30 m. |
| Thatch: water reed, straw or grass | ≈ 48 m² at 0.30 m | About 15 m³ laid and compressed. Gather more than that. |
| Gable infill | 2 × ≈ 4.8 m² | A light stud frame with wattle and daub or boards. Never adobe above the ring beam. |
| Cord, withies or wire | several hundred m | For fixing the thatch and for lashings. |
| Pegs / trenails | ≈ 150 | Dry hardwood, driven into slightly undersized holes. |
| Door, shutter and frames | 1 + 1 + 3 frames | The frames are built into the wall as it rises, anchored with pegged timbers bedded in the joints. |
Tools: Spade, mattock and crowbar · Wheelbarrow or carrying baskets · Buckets and a 5 mm sieve · Bottomless block moulds, 40 × 40 × 10 and 40 × 20 × 10 cm · Batter boards, pegs and string · 12 m knotted cord (3-4-5 triangle) · Water level: 10+ m of clear tube · Plumb bob and 2 m straightedge · Mason's trowel and wooden float · Hand rammer · Axe, adze, saw, auger · Ladders and trestles · Thatching tools: leggett, spars, shearing hook
Construction
Make the blocks first — they need weeks to dry
Blocks must be dry right through before they carry a wall. That takes 2–4 weeks in warm, dry weather, and longer in cool or humid weather, so start moulding before you dig anything. Test the soil first (the three tests are in the building guide). Soak the soil for a day before mixing. The tutorial calls this "sleeping" the mud, and it gets water to every clay particle. Tread in chopped straw. On a flat yard strewn with sand, wet the mould, pack the mix hard into the corners, strike it off level and lift the mould straight up. Dry the blocks in shade for the first few days, because hot sun cracks the faces, then turn them on edge. Make ≈ 800 full blocks and ≈ 120 half-blocks. That is 10% more than the wall needs, because some break and some go into tests.
✓ Check: A dry block dropped from 1 m onto a corner loses the corner and nothing more. A broken block is the same colour right through; a darker core is still wet.
Site it and set out the plan
Choose high ground that drains on every side, clear of any flood mark. Keep it 10 m from other thatched buildings and 20 m from any forge or kiln, which must also be downwind of it (see Permanent shelter). Run the long axis east–west, with the window wall toward the winter sun and the door on the side away from the prevailing weather. Set batter boards (a horizontal board on two pegs) 1 m outside each corner, and stretch strings between them for the wall faces and the trench edges. The boards survive the digging; corner pegs do not. Square the first corner with a 3-4-5 triangle: a 12 m loop of cord knotted at 3 m and 7 m, pulled tight with a peg at each knot.
✓ Check: Both diagonals of the outside rectangle are equal within 10 mm. For 4.80 × 4.40 m, each is 6.51 m.
Dig the trench and lay the footing
Dig a trench 0.60 m wide, centred on the wall line. Go through the topsoil to firm, undisturbed subsoil and at least 0.60 m below finished ground. Go deeper wherever frost reaches deeper, because freezing ground heaves a footing. On a slope, step the trench bottom level rather than letting it slope. Lay the largest flat stones first, bedded in mud mortar with their long sides across the trench, and pack every gap with smaller stone. Every metre, place one stone that reaches right across the trench. Stop 0.10 m below ground level.
✓ Check: Your heel leaves no print in the trench floor, and a steel bar will not push into it by hand. The top of the footing is level to ±10 mm, checked with the water level.
Build the plinth to 0.40 m above ground
Build in stone laid in mud mortar, or lime mortar once you have lime. Make it the full 0.40 m wall width, with the faces set to the strings and the largest bonded stones at the corners. Point the outside joints hard: this face takes rain splash for the life of the house. Leave the doorway open down to floor level for a stone threshold. Then level the top with the water level all round, because every course of adobe above will inherit its error.
✓ Check: Water-level readings at the four corners and at mid-wall are all within ±10 mm, and the plinth top is at least 0.40 m above the ground everywhere.
Lay the damp-proof course
Lay two layers of slate, flat stone or fired tile in mortar across the full width of the plinth top. Place the second layer so its joints fall over the middles of the pieces below. A salvaged bitumen or heavy plastic sheet also works. This course stops damp rising from the stone into the earth. It must be continuous: one gap wicks water into the wall above it.
✓ Check: Sighting along the plinth, you can find no gap anywhere in the layer, and nothing but the plinth below it touches soil.
Lay the walls — about 1 m a day
Dip each block in water for about 5 seconds before laying it. A dry block sucks the water out of the mortar, and the joint never bonds. The mortar is the block soil with coarse sand added as the sandwich test says. Joints are 10–20 mm, and both the horizontal and the vertical joints must be completely filled. Lay in running bond, so every block crosses the joint below it by half a block. At each corner, alternate which wall runs through, so the corners are woven together rather than butted. Set each course to a string line and check it with a plumb bob. Stop each day at about 1 m of new height (published guidance ranges from 1 to 1.5 m). Fresh mortar squeezes out under too much new wall, and the wall leans. Build the door and window frames in as you go, anchored with pegged timbers bedded in the joints.
✓ Check: The wall is plumb within 10 mm over its height, every course is level to the string, and no vertical joint runs straight through two courses.
Set the lintels
At the head of each opening, lay a lintel of seasoned timber or stone, the full wall width, bearing at least 0.30 m into solid wall at each end. That makes them 1.50 m long for the door, 1.40 m for the window and 1.00 m for the vent. Green timber shrinks and twists as it dries and cracks the wall above it, so use wood that was felled and split at least a season earlier. Two more courses of adobe go on above the lintels to reach the ring-beam level.
✓ Check: Every lintel measures ≥ 0.30 m of bearing at both ends and does not rock when pushed.
Build the ring beam
On the last course, run two rails of 75 × 75 mm timber (or 100–120 mm poles) along the inner and outer faces of every wall. Join them with cross pieces every 0.40 m, so they form a ladder. At the corners, the rails of the two walls cross over each other, halved into each other and pegged. Use nails and wire when you have them. Bed the whole beam in mud mortar and fill between the rails with mud and broken block. It must make one continuous belt round all four walls. In an earthquake, it is what stops the walls separating at the corners and falling outward.
✓ Check: Walking the whole ring, you find no break anywhere and a peg in every crossing, and a hard push on a rail moves nothing.
Raise the roof frame
Assemble each couple on the ground: two 4.0 m rafters at 45°, their feet notched over the ends of a 4.6 m tie beam and pegged or lashed. The tie is what stops the roof spreading. Rafters alone push the wall tops outward, and adobe cannot resist a push. Stand the nine couples on the ring beam at 0.60 m centres, and peg or lash each tie to the ring beam. Lay the ridge pole in the crotch at the top, and brace diagonally from end to end until the battens are on. The battens run horizontally across the rafters. The ridge pole and battens both run 0.60 m past each gable to carry the overhang there. Close the gable triangles with a light timber frame and wattle and daub or boards, never heavy earth above the ring beam.
✓ Check: Sighted along from one end, the ridge is straight and the couples stand in one plane, and the frame does not rack when pushed at the ridge.
Thatch it
Start at the eaves and work upward in overlapping courses. Lay each bundle butt-down, fix it to the battens and beat it up tight, to about 0.30 m thick at 45° or steeper. The eaves project 0.60 m beyond the wall. The ridge is the most exposed part of the roof: cap it with a bent-over course of the most flexible material you have, pinned down. A season beside a working thatcher teaches more than any page. The building guide lists where to learn.
✓ Check: Looking up from inside on a bright day, you see no daylight through the roof, the thatch measures 0.30 m at the eaves, and the first heavy rain leaves the inside dry.
Lay the floor
Strip the topsoil inside the walls and ram the subsoil. Spread 0.15 m of clean gravel as a capillary break: it must have no fines, because fine material carries water upward. On it, lay two 5 cm layers of damp earth, each rammed until the rammer rings. Let the floor dry and crack, fill the cracks with a thin clay slurry, then seal it with linseed oil if you have any, or with repeated coats of clay-and-dung wash. The finished floor sits 0.15 m above the outside ground.
✓ Check: Once it is dry, your heel leaves no dent, and the floor is at least 0.15 m above the ground outside the door.
Plaster the walls
Wait until the walls are dry, which takes weeks, not days. Plaster with the same soil as the blocks, with more sand and plenty of chopped straw. Damp the wall, then throw on the first coat hard so it keys into the joints, about 15 mm thick, and let it firm. Follow with a second, finer coat of 5–10 mm. Stop the outside plaster at the damp-proof course with a clean edge, so it cannot carry water from the plinth up into the wall. Never render earth with cement. Put limewash or lime plaster over the mud once you have lime.
✓ Check: Tapped with a knuckle, the plaster sounds solid everywhere, with no hollow patches. Drying cracks are hairline and are filled before winter.
Make the water go away
Grade the ground to fall at least 5% over the first 3 m all round, which is 15 cm of fall in 3 m. Lay a 0.80 m wide, 0.15 m deep strip of gravel under the eaves, so drips cannot splash mud onto the plinth. On the uphill side, about 1.2 m out from the wall, dig a cut-off drain 0.30 m wide and as deep as the footing. Fill it with gravel and run it round the house at a fall of at least 1% to an outlet downhill.
✓ Check: In the first heavy rain, walk round the house. Water runs away from it everywhere, none stands within 3 m, and the drain outlet is running.
Keep fire out from under the thatch
An open fire indoors with no chimney fills the room with smoke. Household smoke kills an estimated 2.9 million people a year (WHO, 2021). A chimney through thatch has to rise 1.8 m above the thatch to keep sparks off it, which means a tall, heavy stack on an earth wall. So for this house, cook outside or in a separate kitchen at least 10 m away and downwind. An indoor hearth belongs to the cold-climate variant below.
✓ Check: There is no open flame inside under the thatch, and nothing that burns is stacked within 1 m of the kitchen fire.
Tolerances that matter
| Dimension | Target | Why it matters |
|---|---|---|
| Plinth top level | ±10 mm all round | Every adobe course inherits it, and the error ends up at the ring beam. |
| Outside diagonals | equal within 10 mm | 6.51 m each here. A plan out of square needs every roof couple cut to a different length. |
| Wall plumb | ±10 mm over 2.2 m | An earth wall that leans keeps leaning as it carries the roof. |
| Wall thickness | ≥ 0.40 m | The earthquake minimum in the adobe tutorial. |
| Wall height | ≤ 6 × thickness, ≤ 3.5 m | A taller, thinner wall falls outward in an earthquake. |
| Wall between corners | ≤ 10 × thickness, ≤ 7 m | A long unsupported wall bows out of plane and collapses. This plan is at the limit. |
| Opening width | ≤ 1.2 m; all ≤ ⅓ of the wall | Cracks start at the corners of openings. |
| Opening to corner, and between openings | ≥ 1.2 m | A narrow pier is the first part of the wall to fail. |
| Lintel bearing | ≥ 0.30 m each end | A short bearing crushes the earth under the lintel end and cracks the wall above. |
| Floor above outside ground | ≥ 0.15 m | Keeps surface water out and the floor dry. |
| Eaves overhang | ≥ 0.60 m | The cheapest wall protection there is. It costs rafter length, nothing else. |
| Ground fall | ≥ 5% for 3 m | Water pooling at the wall base is the commonest cause of earth-wall failure. |
| Block dryness | dry right through | A wet block shrinks in the wall, and the cracks it leaves cannot be repaired. |
How this fails
An earth wall built straight on the ground. Splash and ground damp soften the bottom 30 cm, it erodes back into a hollow, and the wall above loses its seat. The plinth and the drip strip exist to prevent this.
No ring beam, or one broken at a corner. In an earthquake the walls part at the corners and fall outward, and the roof comes down with them. This is how most adobe deaths happen. In Bam, Iran, in 2003, about 26,000 people died, overwhelmingly in collapsing adobe buildings.
Openings too wide, too many, or too near a corner. Cracks start at the corners of openings and run diagonally, and a pier narrower than 1.2 m fails first. The usual way this happens is someone enlarging a window years later.
Rafters without tie beams. The roof spreads under its own weight and the wind, pushing the wall tops apart. The first sign is a crack opening at the top of each corner.
A heavy roof. Earth or stone roofs on earth walls are what crush people in earthquakes. Keep the roof light: thatch, shingles, or tile on a proper frame. Never put a mud roof on this design.
Blocks laid before they are dry, or too much wall laid in one day. The wall either shrinks and cracks as it dries in place, or its fresh courses squeeze out and it leans. Neither can be fixed except by taking the wall down.
Cement render on earth. It traps water in the wall, which softens behind a sound-looking shell until a section falls away. Use mud or lime only.
Green timber. Lintels and rails that shrink as they season open cracks above every opening and loosen every peg.
Timber touching damp earth. Rot and termites start at the ring beam and at the lintel ends. Use heartwood with the bark off, keep the walls dry, and inspect the ends every year.
A fire under thatch. A thatch fire in a one-room house leaves no way out. Allow no open flame indoors without a proper chimney.
How you know it worked
VerificationThe house has come through a full wet season and a winter. The inside faces of the walls are dry to the touch, and the walls show no erosion at the base. No crack at a corner or an opening is wider than a hairline. No drip or daylight comes through the roof, and the floor is dry after the heaviest rain. Re-checked with the water level, the plinth is still level within ±10 mm.
Scaling and variants
More room: add rooms, not length. Each new room is its own box sharing a wall with the last, so every wall stays within 10× its thickness between cross-walls, and every opening rule still applies. Do not add a second storey in adobe.
Earthquake country: build this design plus reinforcement. The tutorial tested several options. One is vertical cane inside the wall, with crushed cane laid flat every fourth course, all tied to the ring beam. Another is an outside mesh of vertical cane and horizontal rope about 0.45 m square, wrapped round every wall and plastered over. Buttresses at the corners help too.
Wet tropics: eaves of 0.90 m or more, a plinth of 0.60 m, and a verandah on the weather side if you can manage one. Thatch at 50–60° sheds heavy rain faster.
Cold winters: take the footing below the local frost depth. Earth walls store heat but insulate poorly, so the thick thatch does most of the work; seal the gable infill tight. An indoor fire needs a masonry chimney built on a gable wall, lined with fired clay, rising 1.8 m above the thatch and swept every year. The alternative is to change the covering to shingles or tile.
Hot and dry: walls of 0.50–0.60 m for more thermal mass, smaller openings, and deeper eaves on the west side. Flat earth roofs are traditional in dry climates, and they are the killer in earthquakes.
Timber and no good soil: wattle and daub in a timber frame. It is lighter, and it survives earthquakes better. Plenty of stone: stone walls in mud mortar on the same plan, with a throughstone every metre and the same ring beam.
Hipped roof: a roof that slopes on all four sides gives every wall an overhang and leaves no gable to fall. The cost is harder framing.