What is a back-to-back house?
A back-to-back house shares not only its party walls at the sides but its rear wall with another dwelling. There is therefore no back: no rear elevation with windows, no rear garden, no back access. Daylight, ventilation and entry all come from the front, and on an end unit from the side as well.
The nineteenth-century background
Back-to-backs were built in huge numbers in the nineteenth century as workers’ housing, above all in the industrial towns of northern England. The reason was purely economic: a small plot, many shared walls, minimal facilities and often poor construction made them extremely cheap to build.
The drawbacks were severe. With so much blind wall and such high urban density, little sunlight got in, and natural ventilation was effectively impossible: without openings on two opposite sides there is no cross ventilation. Public health legislation around the turn of the century led to most being condemned and cleared, and new back-to-backs were prohibited in England by the Housing, Town Planning, etc. Act 1909 — although loopholes meant some were still being built into the 1930s.
The modern revival
The type is returning in contemporary housing, for the same reason as before: it is cheap. Less land per home, less external wall, more shared walls. That makes it attractive for affordable rent and starter homes. Two things have fundamentally changed:
- Ventilation is now mechanical. Mechanical extract or balanced ventilation with heat recovery makes the missing rear elevation a solvable building-physics problem.
- Daylight is handled differently. Roof windows, a rooflight, a void or a tall front glazed screen bring light deep into the plan.
Technical points to watch
- Energetically the type is actually favourable. With only one or two external walls, the heat-loss envelope per dwelling is small, which lowers demand.
- Sound is the biggest risk. Here the rear wall is a separating wall: your living room adjoins someone else’s living room. That calls for a twin-leaf separating wall with no ties. National regulations set the minimum airborne and impact sound performance between dwellings; on a back-to-back, aiming above the minimum is money well spent.
- Fire safety. A separating wall is also a compartment wall; penetrations for services and ventilation must be firestopped.
- No rear access has planning consequences. Bins, bicycles, store access and maintenance access all have to be solved at the front. Design for it, or everything ends up in the front garden.
- There is no rear elevation to maintain — but there is still a roof, and that roof becomes the only surface adjoining two dwellings.
Design checks for a back-to-back house
- Twin-leaf separating wall with no ties: The rear wall adjoins another living room, so sound is the biggest risk.
- Sound performance above the minimum: National regulations set the minimum; aiming higher is money well spent.
- Firestop all service and ventilation penetrations: The separating wall is also a compartment wall.
- Bins, bicycles and access solved at the front: There is no rear access, so plan storage and maintenance access at the front.
Related terms
- Separating wall
- Twin-leaf party wall
- Balanced ventilation
- Fire compartment
- Building plot
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