An overhang is the part of the roof that extends beyond the external wall. It protects the facade against rain, keeps direct sunlight out of windows, and gives the building a finished appearance. For covered structures, carports, and verandas, the overhang is often extra large because providing shelter is the main purpose.
Why is an overhang important?
The overhang serves multiple functions:
1. Facade protection — Rainwater running off the roof does not fall directly against the wall. This prevents moisture damage, algae growth, and soiling of the facade.
2. Sun shading — In summer, an overhang blocks the high sun, while the low winter sun can still shine in.
3. Foundation protection — Water is kept further from the base of the building.
4. Aesthetics — A well-proportioned overhang gives a building more character and depth.
How large should an overhang be?
The size of the overhang depends on its function:
| Application | Overhang (indicative) |
|---|---|
| House | 30-60 cm |
| Shed or garden building | 20-40 cm |
| Covered structure | 60-150 cm (purpose = shelter) |
| Carport | 50-100 cm per side |
| Veranda | 200-400 cm (fully covered) |
With a larger overhang, the wind load increases. Above 60 cm, the structure must be engineered accordingly.
Overhang for covered structures, carports, and verandas
For a covered structure, carport, or veranda, the overhang is essentially the whole purpose of the construction. Here the purlins are longer than the distance between the posts, so the roof extends beyond all sides.
Points to consider:
- Wind load — A large overhang catches a lot of wind. Use strong connections and consider wind bracing
- Drainage — With a large overhang, a lot of water runs off the roof. Provide a gutter or sufficient distance to the boundary
- Structure — The purlins or trusses must be long enough to form the overhang. For large overhangs, braces (angled supports) 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 — For sheds, the overhang is sometimes left open, so the purlins and rafters are visible
Common mistakes
- Overhang too small on a shed — The facade gets no protection and the timber weathers faster
- No gutter with a large overhang — All water falls in one spot, saturating the ground around the building
- Overhang forgotten on the construction drawing — The overhang must be included in the total roof dimensions
Related terms
- Fascia board
- Gutter
- Purlins
- Post
- Pergola beam