Gutters collect the water off the roof and downpipes take it to the ground, a drain or a rainwater tank. On a house roof most gutters are PVC or aluminium. This guide uses the PVC system from Marley Pipe Systems, whose South African installation guide sets out clear rules, to show how to count every part.
The parts
- Gutter lengths. Marley’s Vynadeep half-round and Streamline Double-Flo gutters come in 3, 4.5 and 6 m lengths.
- Union clips join two lengths of gutter.
- Fascia brackets hold the gutter to the fascia board.
- Outlets lead water from the gutter into the downpipe.
- Stop ends close the ends of each run.
- Internal and external angles turn corners.
- Downpipes come in 3 m lengths, with bends, a shoe at the bottom and pipe clips to the wall.
Choosing a system
Marley’s two PVC systems look different but install the same way. Vynadeep is a half-round gutter with round downpipes. Streamline Double-Flo has a squarer profile with square downpipes, clips and sockets. Pick one and buy every part from the same system, because outlets, angles and clips only fit their own gutter.
Marley’s installation rules
- Fascia brackets no more than 1 m apart.
- A bracket within 10 cm of every joint and fitting.
- Pipe clips at the downpipe shoe, halfway up and at the top of each downpipe.
- Gutters can be level or have a slight fall towards the outlet.
- Offsets around the eaves are made from two downpipe bends with a short length of pipe between them.
Counting the parts
- Measure the length of every eave that drains into a gutter, and count the separate runs and the corners.
- Decide where the outlets go. Put them near valleys, which carry a lot of water, and so that no stretch of gutter is too long for one outlet.
- Gutter lengths = total length × a small allowance for joints and cutting ÷ length of each piece.
- Brackets = total length ÷ 1 m, plus extras at the ends of runs and next to joints and fittings.
- Downpipes = outlets × (eaves height ÷ 3 m), rounded up.
Worked example: 30 m of eaves in two runs of 15 m, eaves 2.6 m high, with one outlet for every 12 m of gutter. Each run needs two outlets, four in total. Gutters = 30 × 1.05 ÷ 4.5 = 7 lengths. Brackets = 30 + 2 = 32. Each downpipe is one 3 m length, so four downpipes, with four shoes, eight bends for the offsets and twelve pipe clips. The gutter calculator produces this list.
| Part | Quantity | How it is counted |
|---|---|---|
| Gutter, 4.5 m | 7 | 30 m × 1.05 ÷ 4.5 m |
| Fascia brackets | 32 | One per metre plus one per run |
| Union clips | 5 | Joints between lengths |
| Stop ends | 4 | Two per run |
| Outlets | 4 | Two per 15 m run |
| Downpipes, 3 m | 4 | One per outlet for 2.6 m eaves |
| Bends, shoes, clips | 8, 4, 12 | Two bends, one shoe and three clips per downpipe |
Where the water goes
Downpipes must discharge where the water can drain away from the house: into a stormwater drain, a channel, or a rainwater tank. Never let them discharge against a wall or onto paving that slopes towards the house; that is a common cause of damp. If you want to keep the water, the rainwater tank calculator shows how much the roof collects and which JoJo tank holds it.
Installation tips
- Fix the first bracket as high as possible at the far end of the run, and the last near the outlet, then use a builder’s line to set the brackets between them.
- Cut gutters square and clean off burrs so joints seal properly.
- Secure the gutter while you cut it, as Marley’s guide shows.
- Clean gutters before the rainy season, and fit leaf screens under trees.
This guide is general information for estimating. It is not engineering, legal or tax advice. Check SANS 10400 (the National Building Regulations) and your local municipality’s building control officer for your project.