What is a Shaft?
A shaft is a vertical, enclosed space within or attached to a building, intended for routing pipes, cables, a lift, or ventilation. The shaft forms a protected passage from one floor level to the next, keeping services concealed and preventing fire from spreading between floors.
Types of shaft
| Type | Contents | Application |
|---|---|---|
| Services shaft | Pipes, cables | Residential, offices |
| Lift shaft | Lift car + counterweight | Multi-storey buildings |
| Ventilation shaft | Air ducts | Residential ventilation (MVHR, HRV) |
| Flue / chimney shaft | Combustion gases | Boiler, open fireplace |
Fire safety
A shaft that passes through multiple floor levels must be constructed to be fire-resistant. This prevents fire and smoke from travelling via the shaft from one storey to another.
Requirements (Building Regulations):
- Shaft walls: minimum 30 minutes fire resistance (REI 30)
- Penetrations through shaft walls: intumescent fire sleeves or seals
- Access doors (inspection hatches): fire-rated
DIY: building a services duct yourself
During a bathroom renovation or kitchen refit, a small duct for water pipes and drains is sometimes required:
- Build a timber frame from 45 × 45 mm studs
- Line with one layer of 12.5 mm plasterboard (ground floor) or fire-rated board (F30) for multi-storey
- Leave an inspection hatch opening
- Paint or tile the finished duct
> Always include an accessible inspection hatch — stop valves and connections must remain reachable.
Shaft vs. duct vs. channel
- Shaft — vertical space, multiple storeys
- Duct (boxing) — smaller enclosure for a single pipe run
- Channel (air duct) — horizontal air routing (ventilation)
Related terms
- Home automation
- Floor insulation
- Ceiling insulation
- Plasterboard
- Building Regulations
- Cavity wall
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