What is a roof outlet?
A roof outlet (also called a rainwater outlet or drain fitting) is an opening or device in a building structure through which rainwater is drained in a controlled manner. The term is used in construction for various water-drainage fittings on roofs, gutters and walls.
How does a roof outlet work?
A roof outlet ensures that water collecting on a flat roof, behind an upstand or in a gutter can flow away to a downpipe or rainwater drainage system. The outlet is placed at the lowest point of the area to be drained, so water runs towards it naturally by gravity (falls).
Types of outlets:
- Flat-roof outlet — a drain in a flat roof, connected to a rainwater downpipe
- Overflow outlet — an emergency drain that activates when the primary outlet is blocked
- Scupper — an outlet through the wall, allowing water to fall freely to the outside
- Gutter outlet — the point where the gutter meets the downpipe
Applications
- Flat roofs — roof drain outlets with leaf guards prevent blockages
- Balconies and roof terraces — outlets in the floor or through the parapet
- Car parks — drainage points in the concrete slab
- Retaining walls — weep holes to prevent water pressure behind the wall
Related terms
- Fall (gradient)
- Rainwater downpipe
- Gutter
- Overflow
- Scupper
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