Log house
Where straight timber grows and there is no clay or stone, the fastest permanent walls an axe can raise: structure, enclosure and insulation in one piece.
Build
Tier 1 · Neolithic
Shelter
Moderate — heavy lifting and careful notching, and the logs must season for six months first
≈ 100–150 person-days after seasoning
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 log wall is structure, enclosure and insulation in one piece, raised with an axe, a saw and a crew. The rules are few, and each one prevents a known failure: keep the logs off the ground, cut every notch so it sheds water, and leave room over every door and window for the walls to settle as the logs dry and shrink across the grain.
The dimensions follow the US Forest Service manual, Fickes' Building with Logs: logs 250–300 mm across, cut in late autumn or winter, peeled and seasoned for six months, laid on a continuous stone foundation and joined at the corners with the saddle notch. This is one of the level-1 options on the Dwellings track; the earth house is the one for clay.
Section across the house
Fig 1
Earth / subsoilMasonry / brickTimberLoose fill / grainVoid / air
The saddle notch, and the corner in plan
Fig 2
Timber
Keyed parts
| 1 | Stone foundation wall | Continuous, in lime or clay mortar, with its top at least 300 mm above the ground and small vents for air. Never logs on the ground: wood in contact with earth decays. |
| 2 | Sill log | The first course, hewn with a flat face 50–75 mm wide on its underside so it lies still on the foundation. The end-wall foundations stand half a log higher than the side walls. |
| 3 | Wall logs, 250–300 mm | Straight, with as little taper as possible. The largest at the bottom, and butts and tops alternated so the wall rises level. Cedar, pine, fir and larch, in that order. |
| 4 | Saddle notch | Cut from the underside of the upper log, half the lower log's diameter deep, and cupped so the weight bears on its outer edges. The lower log is never cut, so its top sheds water. |
| 5 | Projecting ends | Logs 1.8 m longer than the inside dimension, so each end runs about 0.6 m past the corner and the notch is not near a split end. |
| 6 | Chinking and daub | Split or pole chinking wedged into the gaps, then lime or clay daub with hair, held by nails driven every 50–75 mm. Or no chinking at all: see scribed walls under Scaling and variants. |
| 7 | Window and door frames on splines | Frames stand on the sill log and slide in a vertical groove in the cut log ends, so the walls can settle past them without racking them. |
| 8 | Settlement gap | Above each frame, 65–100 mm for a door and 40–75 mm for a window, filled loosely with a compressible insulation that takes no load. |
| 9 | Floor joists | Logs 100–200 mm across, hewn level on top, notched into the sill logs about 600 mm apart, with air beneath them. |
| 10 | Purlins and ridge log | Logs about 200 mm across, running gable to gable about 610 mm apart, with the gables built up in logs at the same time. |
| 11 | Shake roof | Hand-split shakes 760–910 mm long, riven with a froe from straight-grained, knot-free wood, laid on the purlins at about 40°. |
| 12 | Eaves | Projecting 600 mm past the wall, so rain falls clear of the log faces and the notches. |
Specifications
| Inside plan | 4.00 × 5.00 m = 20 m² | Measured inside, log to log, because outside sizes vary with the logs. |
| Logs | 250–300 mm at the top end | Fickes: 10–12 in, taper as slight as possible. |
| Species | cedar, pine, fir, larch | In that order of preference. |
| Log length | inside dimension + 1.8 m | 6.80 m and 5.80 m here. |
| Felling and seasoning | late autumn or winter; peeled; ≥ 6 months on skids | Spring and summer logs peel easily but check badly, and insects and fungi are active. |
| Walls | 9 courses, ≈ 2.5 m to the eaves | |
| Corner | saddle notch, half a diameter deep | Cut from the underside of the upper log. |
| Foundation | continuous stone, top ≥ 300 mm above ground, vented | End walls half a log higher than the side walls. |
| Settlement gap over openings | door 65–100 mm; window 40–75 mm | Fickes: 2½–4 in for a door 6 ft 8 in to 7 ft; 1½–3 in for a window. |
| Floor joists | 100–200 mm logs, hewn level | Notched into the sill logs. |
| Roof | log purlins ≈ 610 mm apart; shakes 760–910 mm | Pitch about 40°. |
| Eaves | 600 mm |
Bill of materials
| Material | Quantity | Notes and substitutes |
|---|---|---|
| Wall logs, 250–300 mm, peeled and seasoned | ≈ 36, plus ≈ 14 for the gables | 18 at 6.8 m and 18 at 5.8 m for nine courses; the gable logs shorten course by course. About 15–17 m³ in all. |
| Purlin and ridge logs, ≈ 200 mm | ≈ 11 at 6.8 m | Five a side about 610 mm apart, and the ridge; the top wall logs carry the roof over the walls. |
| Floor joist logs, 100–200 mm | ≈ 10 at 4.3 m | About 600 mm apart, hewn flat on top. |
| Floorboards, 25 mm | ≈ 20 m² | Sawn, or split and adzed flat. |
| Shakes | for ≈ 51 m² of roof | 760–910 mm bolts of straight-grained, knot-free wood, split with a froe. |
| Stone for the foundation | ≈ 5.5 m³ | About 19 m of wall, 400 mm wide and 700 mm deep, laid in lime or clay mortar. |
| Chinking and daub | split poles or wedges; ≈ 0.5 m³ of lime or clay plaster | Hair mixed into the daub helps it hold; nails every 50–75 mm hold it in place. |
| Seasoned timber for frames and splines | 1 door, 2 windows | Jamb logs 50–75 mm larger than the wall logs, if frames are made of logs. |
Tools: Felling axe and crosscut saw · Broadaxe or adze for hewing · Drawknife or bark spud for peeling · Wing dividers with a level bubble, or a log scribe · 50 mm gouge · Log dogs · Spirit level and plumb board · Froe and mallet for shakes · Pike poles, ropes and skids
Construction
Fell in winter, peel, and season for six months
Cut straight, even logs in late autumn or winter, when insects and fungi are dormant and the wood checks less as it dries. Trim off every knot and limb, peel the bark, and lay the logs in a single tier on skids well off the ground, 50–75 mm apart, with any curve uppermost so their weight straightens them. Leave them at least six months.
✓ Check: After six months the logs are lighter, their ends show fine checks but no soft or stained wood, and bark comes away nowhere.
Build the foundation
Build a continuous stone wall in lime or clay mortar, deep enough to reach firm ground and with its top at least 300 mm above the ground outside. Leave small vents through it for air under the floor. Build the two end walls half a log higher than the side walls, because the logs of the end walls sit half a log above those of the side walls.
✓ Check: The foundation top is level to within 10 mm round each wall by the water level, stands at least 300 mm above the ground, and has vents on every side.
Lay the sill logs square
Hew a flat face 50–75 mm wide on the underside of each sill log, where it rests on the foundation. Set the side sills first, then the end sills across them, placed so that the inside faces give the exact inside dimensions, and hold them with log dogs.
✓ Check: The two inside diagonals are equal to within 10 mm, and no sill rocks on its foundation.
Cut every corner as a saddle notch
Lay the next log across the one below and dog it in place. Set the wing dividers to half the diameter of the log below. With one point riding the curve of the lower log and the level bubble kept upright, draw the other point along the upper log on all four sides of the corner. Roll the log over, chop the notch out roughly with the axe, and finish to the line with the gouge, cupping it slightly so the weight comes on the outer edges. Never cut the lower log.
✓ Check: Rolled back, the log beds down on the one below without rocking, and no daylight shows through the notch from outside.
Raise the walls level
Put the largest logs at the bottom. Lay each course with butt and top ends alternated, so the wall rises evenly, and check all four corners with the level after every course; correct a high corner by cutting that notch a little deeper. Carry the logs up with ropes, skids and pike poles, and keep everyone out from under a log being rolled up.
✓ Check: After every course, the four corners are level with each other to within about 10 mm.
Frame the openings, and leave room for settling
Cut the door and window openings once the wall is above them. Cut a vertical groove in the log ends each side, fit a spline, and stand the frame on the sill log so the wall can slide down past it. Leave 65–100 mm above a door frame and 40–75 mm above a window frame, and fill the gap loosely with a compressible insulation that takes no weight.
✓ Check: The frames are plumb, the settlement gap is there above every one, and the head log does not touch any frame.
Floor, gables, purlins and shakes
Notch the floor joists into the sill logs about 600 mm apart and hew them level on top before laying the boards. Build the gables up in logs at the same time as the purlins, pegging the two together, with purlins about 610 mm apart and a ridge log at the top. Split shakes 760–910 mm long with a froe and lay them on the purlins, with the eaves projecting 600 mm.
✓ Check: The floor is level both ways, and after heavy rain no water has come through the roof or run down the inside faces of the logs.
Chink, daub, and keep fire in masonry
Wedge split or pole chinking into the gaps between logs, drive nails every 50–75 mm along the gap, and daub with lime or clay plaster mixed with hair. Heat the house only through a masonry chimney, built as in the fireplace and chimney build, with 50 mm of air between it and every log.
✓ Check: On a bright day no daylight shows between the logs from inside, and a 50 mm gauge passes between the chimney and every log near it.
Tolerances that matter
| Dimension | Target | Why it matters |
|---|---|---|
| Foundation height | ≥ 300 mm above ground | Splash and ground damp rot the bottom logs first, and they carry everything above them. |
| Corners level | within 10 mm, every course | The error builds up course by course, and the top plate has to be level for the roof. |
| Inside diagonals | equal within 10 mm | A plan out of square makes every purlin and roof log a different length. |
| Settlement gap over a door | 65–100 mm | Less, and the settling wall jams the door and crushes the frame. |
| Settlement gap over a window | 40–75 mm | Less, and the glass cracks as the head log comes down. |
| Seasoning | ≥ 6 months, peeled | Green logs shrink more in the wall, open the chinking, and settle further. |
How this fails
Logs on or near the ground: the bottom logs rot within a few years, and the whole wall sags onto them.
No settlement gap: as the logs dry and shrink across the grain, the walls come down onto the door and window frames, jamming doors and cracking glass.
A notch cut into the top of the lower log: it holds rain, and the corner rots from the inside.
Logs cut in spring or summer, or left unpeeled: they check badly and carry the insects and fungi that were active when they were felled.
An open fire without a masonry chimney, or a stove pipe near the logs: the house burns. See the fireplace and chimney build.
Daub with nothing to hold it: it falls out in the first winters, and the wind comes through.
Short eaves: rain on the wall faces soaks the logs and the notches, and the ends check and rot.
How you know it worked
VerificationAfter a year: the four corners of the top course are still level with each other within about 10 mm; doors and windows open freely, with the settlement gaps partly closed but not gone; no daylight shows between logs; and the bottom logs are dry and sound when probed with a knife.
Scaling and variants
Scribed walls, no chinking. Scribe and groove the underside of every log along its whole length so it saddles the log below, the Scandinavian method Fickes describes. It is slower to cut and needs no chinking or daub.
Dovetail corners. Flush corners, stronger, and good with hewn logs, but the cut faces hold water, so they need wide eaves.
Hewn, square logs. Flat faces take less chinking and give a flat wall inside, for more axe work.
A second room. Build a second pen beside the first and join them under one roof, rather than making one pen longer than straight logs allow.