A longhouse is a single long building divided along its length into family sections of 4-6 m, with doors opening to the outside and one continuous roof above all of them. It uses among the least material per family of any multi-family form and keeps every section warm from its neighbours’ fires, but one burning section threatens the whole building, so give each hearth its own flue, put firebreaks through the roof void and keep its long wall at least 15 m from other buildings.
Part of Multi-Family Housing Design
A longhouse is a linear multi-family building in which families occupy consecutive sections of one long structure, as in Norse, Iroquois and Borneo building traditions.
One Roof Saves Material And Spreads Fire
The multi-family guide describes the form: each family takes a section 4-6 m long across the building’s full width of 4-6 m; there are two long exterior walls shared among all families; the structural design is simple, with no complex corners; and a shared corridor or common area can run the length. Its listed historical examples are Viking longhouses up to 50 m long, Iroquois longhouses up to 100 m long and Borneo longhouses.
Its disadvantages are as listed there: poor acoustic privacy, fire that threatens the entire building, no way for a family to expand its section alone, and no buffer between personalities. Best use: the founding phase, when materials and labour are scarce and cohesion is high.
Worked Example: Units And Land
Inputs: section length 4-6 m; building lengths of 50 m and, for the largest historical example, 100 m; the 8-unit longhouse of the guide’s comparison table.
- Units in 50 m: 50 ÷ 6 ≈ 8 to 50 ÷ 4 ≈ 12 families.
- Units in 100 m: 100 ÷ 6 ≈ 16 to 100 ÷ 4 = 25 families.
- Length of an 8-unit longhouse: 8 × 4 = 32 m to 8 × 6 = 48 m.
- Separation from a neighbouring building: the long wall is a radiator. At a 1,000 C flame, a burning wall 30 m long and 3 m high needs about 15 m of clear ground before its flux falls below the roughly 12.5 kW/m² level at which wood ignites (Fire Breaks and Building Spacing). The fire guide’s 5 m is for non-combustible walls and would not be enough for a timber one.
At 3.75-5 people per unit, the 8-12 families of a 50 m longhouse are 30-60 people.
What You Need
- A site with room for the long axis and a cleared margin on both long sides
- Walls and roof of non-combustible or fire-resistant material where possible
- A masonry or earth firewall between groups of sections
Method
Step 1: Lay out the sections along the axis; give every family an outside door.
Step 2: Keep hearths apart. Give each its own flue with the clearances in Fire Prevention in Settlements (chimney at least 5 cm from wood).
Step 3: Divide the roof void. Build firewalls of masonry or earth that rise through the roof, so flame and smoke do not run the full length.
Step 4: Ventilate each section with an inlet and an outlet, so a shared hearth or fire does not leave carbon monoxide in sleeping spaces (Indoor Use and Ventilation).
Step 5: Plan the sound. Walls between sections should be thick and dense (Sound Isolation Between Units).
Common Mistakes
- No firewalls — the chief reason a longhouse fire becomes total.
- Sharing one hearth chimney among several families.
- Building it near other buildings as if it were a single house.
Safety
Fire and smoke in a long building
Every section needs a door to the outside, and the corridor or common area must never be blocked at both ends. Smoke and carbon monoxide travel the length of an open roof void; sleeping spaces need ventilation, and no one should sleep next to an unvented fire.
What’s Next
- Learn next: Row Houses — separate roofs with shared side walls
- Combine with: Structural Bracing — keeping a long building rigid