What is a gutter?
A gutter is a horizontal channel along the lower edge of the roof that collects rainwater and directs it via a downpipe to the sewer, a rain barrel, or the garden. Without a gutter, all the water from the roof would run down the facade, causing moisture damage, algae growth, and soil erosion around the building.
Types of gutters
Hanging gutter (suspended gutter)
The most common gutter on residential homes. It hangs from gutter brackets underneath the roof, attached to or just below the fascia board.
Box gutter (built-in gutter)
A gutter built into the roof structure, often found on older buildings and flat roofs. Not visible from the ground.
Mast gutter
A wide, shallow gutter mounted against the facade. Mainly used on commercial buildings and sheds.
Materials
| Material | Lifespan | Price | Suitable for |
|---|---|---|---|
| Plastic (PVC) | 15-25 years | Low | Shed, garden house, DIY |
| Zinc | 30-50 years | Medium | Homes, garages |
| Aluminium | 30-50 years | Medium-high | Homes, modern construction |
| Copper | 50-100 years | High | Heritage buildings, luxury construction |
For DIY projects, plastic (PVC) is the most practical: affordable, easy to install, and available in standard sizes.
Installing a gutter
Materials
- Gutter sections (standard 2 or 4 metre lengths)
- Gutter brackets (every 60-80 cm)
- Corner pieces and connectors
- End caps
- Outlet (downpipe connection)
- Downpipe + brackets
Steps
- Determine the slope — The gutter must slope slightly towards the downpipe: approximately 3 mm per linear metre
- Install the first bracket — At the highest point, just below the roof sheathing
- Install the last bracket — At the lowest point (at the downpipe)
- String a line — Between the first and last bracket as a reference
- Install intermediate brackets — Every 60-80 cm along the line
- Click the gutter in — PVC gutters click into the brackets
- Make connections — Connectors with rubber seals
- Outlet and downpipe — Connect at the lowest point
Sizing
The gutter size depends on the roof area:
| Roof area | Gutter size (width) | Downpipe (diameter) |
|---|---|---|
| Up to 30 m² | 100 mm | 70-80 mm |
| 30-60 m² | 125 mm | 80 mm |
| 60-100 m² | 150 mm | 100 mm |
| Over 100 m² | Two drainage points or 200 mm | 100-120 mm |
Common mistakes
- No slope — Water stays in the gutter, starts to smell, and the gutter sags under the weight
- Too few brackets — The gutter will sag. Maximum 80 cm between brackets.
- Gutter too low — Water overshoots the gutter during heavy rain. The back of the gutter should sit slightly higher than the front.
- No leaf guard — Leaves clog the outlet and downpipe
Related terms
- Fascia board
- Eaves overhang
- Slope
- Flat roof