Roof Plumbing and Drainage: Gutters, Downpipes, Flashings and Box Gutters Explained

Roof plumbing is the system that collects and directs rainwater from the roof. Gutters are only one part of it. Downpipes, flashings, valleys, box gutters and stormwater connections all need to work together to keep water moving in the intended direction.

For more detail on the service itself, see our roof plumbing page.

Gutters

Gutters collect runoff along roof edges and direct it toward outlets and downpipes. Their size, condition and fall all affect performance.

Downpipes

Downpipes move water from the gutter to the stormwater system or approved discharge point. Restrictions or poor connections can cause roof drainage to back up.

Roof flashings

Flashings help manage water around penetrations, junctions and changes in roof geometry. Damaged or incorrectly detailed flashings can allow water into the building.

Box gutters

Box gutters sit within or between sections of a roof rather than along an exposed edge. Because overflow can affect the building quickly, their drainage and maintenance are especially important.

Roof valleys

Valleys concentrate water from multiple roof planes. Problems can occur if debris, damage or poor drainage restricts the flow.

Stormwater connection

Roof drainage does not end at the downpipe. The underground stormwater system also needs to carry the collected water away.

Look at the complete water path

When diagnosing a roof water problem, follow the path from roof surface to gutter, downpipe and stormwater outlet rather than looking at one component in isolation.

Related plumbing services

You may also find these related service pages useful: roof plumbing, roof flashings, box gutters.

Need help with this type of plumbing?

If you are planning this work or dealing with a problem now, see our roof plumbing service page for the relevant plumbing options and next steps.