A roof penetration is a specially designed building element that allows pipes, cables or ducts to pass through the roof surface while maintaining a watertight seal. It prevents water from entering the building at points where the roof membrane is interrupted.
How it works
Every roof has points where services need to pass through the roof surface — ventilation pipes, chimneys, antenna cables or solar panel wiring. Without a proper roof penetration, rainwater would enter the building at these points.
A typical roof penetration consists of:
- Base plate — shaped to match the roof covering (tiles, bitumen, metal sheeting)
- Pipe collar — receives the pipe or cable that passes through
- Sealing sleeve — creates a watertight connection between the pipe and the base plate
Application
Roof penetrations are used in various situations:
- Soil vent pipes — waste water drainage systems require ventilation above the roofline
- Extractor ducts — exhaust air from kitchens and bathrooms
- Aerials and satellite dishes — cables and masts pass through the roof
- Solar installations — cables from photovoltaic panels
- Chimneys — flue pipes penetrate the roof surface
Materials
Roof penetrations are manufactured from different materials depending on the roof type:
- Plastic — standard applications on pitched roofs
- Lead — traditional solution, very durable and malleable
- EPDM rubber — flexible sleeves that fit various pipe diameters
- Aluminium — lightweight and corrosion-resistant
Related terms
- Roof covering
- Roof sheathing
- Roof flashing
- Chimney
- Waterproofing
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