Rainwater drainage
How to install plastic guttering
Installing plastic guttering is a practical job that protects your fascia boards and foundations from water damage. The critical element is setting the correct fall — plastic guttering needs a slight slope towards the downpipe outlet, typically around 1 in 600, so water runs freely rather than sitting and overflowing.
Video: Wickes — UK DIY and building materials chain. Features FloPlast, a UK rainwater system brand used across domestic and commercial properties throughout Britain.
Step-by-step guide
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Measure the run and plan the layout
Measure the full length of the eaves run from one end to where the downpipe will be positioned. Note any external or internal corners. The downpipe outlet should ideally be at the lowest point of the run. For runs longer than about 6 metres, consider placing the outlet in the middle and running the fall from both ends towards it. Sketch the layout before buying materials.
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Set the fall with a string line
Fix a nail or temporary bracket at the high end of the run, just below the roof line so the gutter will sit with its back edge tight to the fascia. Tie a string line to this point and run it to the outlet end, setting a fall of approximately 1 in 600 (roughly 6 mm drop per metre of run). Use a spirit level to check the string is straight across before adding the fall. This string line becomes your guide for fixing all the brackets.
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Fix the outlet and end brackets first
Screw the downpipe outlet bracket to the fascia at the low end of the run at the correct height below the string line. Fix the bracket at the highest end of the run next. These two fixed points define the run. Use stainless steel or zinc-plated screws into sound fascia timber — avoid overtightening into old or soft fascia boards.
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Fix intermediate brackets at 1-metre spacings
Work along the run, fixing fascia brackets every 900 mm to 1 metre, aligned with the string line. Check each bracket sits at the correct height against the line before screwing off. Closer bracket spacing may be needed in areas prone to heavy rainfall or where the roof pitch throws water hard into the gutter. Snap the brackets open so the gutter can be clicked in later.
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Cut and join the gutter lengths
Measure and cut the gutter sections to length using a fine-tooth saw or a purpose-made gutter cutter. Deburr the cut ends with a file or abrasive paper. Slide gutter union connectors onto the lengths where two sections meet, ensuring the rubber seal is seated correctly in the connector. Leave a small expansion gap (approximately 5 mm) between sections to allow for thermal movement.
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Fit corners, stop ends, and the outlet
Clip any 90-degree corners or running outlet unions into place before fitting the gutter sections. Fit stop ends to all open ends of the run. Press each piece firmly until you hear a click, confirming the seal is seated. Check that the gutter fall is maintained through corners by holding a spirit level along the top of the installed sections.
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Clip the gutter into all the brackets
Starting from one end, press the gutter up into the open brackets and clip the front lip over the bracket retaining edge. Work along the run, clicking each bracket closed. Check the gutter runs smoothly without dips or high spots by pouring a bucket of water at the high end and watching it run to the outlet.
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Fit the downpipe and connect to the drain
Clip the downpipe offset brackets and pipe clips to the wall below the outlet, keeping the pipe plumb and close to the wall. Connect the offset elbows from the outlet down to the vertical run of downpipe. At the base, fit a shoe to direct water away from the wall into a drain, water butt, or soakaway. Ensure the shoe does not direct water towards foundations or a neighbour's property.
Tips and common mistakes
- Getting the fall right is everything — too flat and water sits and overflows; too steep and it shoots past the outlet.
- Always check fascia boards are sound before fixing brackets — rotten fascia needs replacing before new guttering is fitted.
- Use stainless steel screws for bracket fixing — standard zinc screws corrode in wet conditions and can fail within a few years.
- Allow for thermal expansion in the joints — plastic guttering expands and contracts significantly with temperature changes.
- Test with a bucket of water before finishing — this immediately shows any joins that are not seating properly or areas where the fall is incorrect.
- Match the profile (half-round, square, ogee) to the existing guttering on your property or neighbouring houses for a consistent appearance.
Prefer to have this done professionally? Contact The Sandwich Handyman — guttering installation and replacement is a regular property maintenance job across Sandwich and East Kent.