What is a roof overhang?
A roof overhang is the part of the roof that extends beyond the exterior wall. It protects the facade against rain, keeps direct sunlight out of windows and gives the building a finished appearance. On shelters, carports and verandas, the overhang is often extra large because providing cover is the main purpose.
Why is a roof overhang important?
The overhang serves multiple functions:
- Facade protection — Rainwater running off the roof does not fall directly against the wall. This prevents moisture damage, algae growth and facade soiling.
- Sun shading — In summer, an overhang keeps the high sun out, while the low winter sun can still enter.
- Foundation protection — Water is kept further from the base of the building.
- Aesthetics — A well-dimensioned overhang gives a building more character and depth.
How large should a roof overhang be?
The size of the overhang depends on its function:
| Application | Overhang (indicative) |
|---|---|
| House | 30-60 cm |
| Shed or garden shed | 20-40 cm |
| Shelter | 60-150 cm (purpose = cover) |
| Carport | 50-100 cm per side |
| Veranda | 200-400 cm (fully covered) |
With a larger overhang, wind load increases. Beyond 60 cm you must calculate the structure for this.
Overhang on shelters, carports and verandas
On a shelter, carport or veranda, the overhang is essentially the entire purpose of the structure. Here the purlins are longer than the distance between the posts, so that the roof extends on all sides.
Points of attention:
- Wind load — A large overhang catches a lot of wind. Use sturdy connections and consider wind bracing
- Drainage — With a large overhang, a lot of water runs off the roof. Ensure a gutter or sufficient distance from the boundary
- Structure — The purlins or trusses must be long enough to form the overhang. For large overhangs, diagonal braces are sometimes used
Finishing the overhang
The underside of the overhang (the so-called soffit) is often finished with:
- Timber boarding — Planks or plywood on the underside for a neat appearance
- Fascia boards — The vertical board at the end of the overhang, where the gutter is usually attached
- Open overhang — On sheds, the overhang is sometimes left open so that the purlins and rafters are visible
Common mistakes
- Too small an overhang on a shed — The facade gets no protection and the timber weathers faster
- No gutter with a large overhang — All the water falls at one point, saturating the ground around the building
- Forgetting the overhang in the building plan — The overhang must be included in the total roof dimensions
Related terms
- Fascia board
- Gutter
- Purlins
- Post
- Pergola beam