Practical points for fitting eaves gutter and downpipes so roof water is collected and carried away cleanly.
Rainwater (surface water) guttering looks simple, but it only works if it is set out and supported correctly. Use this as a revision checklist of good practice, then size the system from current guidance.
- Set the fall. Lay the gutter with a slight, even fall towards the outlet so water keeps moving and does not stand; too little fall lets it pond, too much drops the gutter below the roof line.
- Position under the roof edge. Set the gutter so water shedding off the roof falls into it and is not thrown over the front in heavy rain.
- Support it properly. Space the brackets closely enough to carry the gutter full of water without sagging, and add support near outlets, joints and stop ends.
- Make the joints. Assemble unions, angles and outlets so they seal and allow for thermal movement, as plastic gutter expands and contracts noticeably.
- Fit the downpipes. Run downpipes from the outlets down to the drainage point, clipped to the wall, with offsets (swan necks) to clear the eaves where needed.
- Discharge correctly. End the downpipe at a suitable point such as a gully, a back-inlet gully or a soakaway, keeping surface water separate from foul where the system is separate.
- Size for the roof. Make sure gutter, outlet and downpipe sizes suit the roof area and rainfall so they do not overflow in a storm.
Set the fall, support it, seal it and send the water somewhere suitable. Confirm sizing and discharge options against Approved Document H.
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