Guttering is a simple system in principle — collect rainwater from the roof, direct it to a downpipe, and get it away from the building — but failures are one of the most common causes of damp in UK properties. Blocked, cracked, or poorly-fitted gutters allow water to run down external walls and saturate brickwork, leading to internal damp and eventually structural damage to fascias and soffits. Maintenance and timely replacement are much cheaper than the remedial work that follows neglect.
For a typical three-bedroom semi-detached house with a simple pitched roof, replacing like-for-like uPVC guttering and downpipes costs £400–£900 including labour. Cast iron or aluminium systems on older or character properties cost considerably more.
Gutter Materials Compared
uPVC (unplasticised polyvinyl chloride)
By far the most common guttering material on UK homes built after 1970. uPVC is lightweight, cheap, and available in any builders’ merchant. It is joined using push-fit connectors with rubber seals that eventually perish and leak — this is the most common failure point. uPVC becomes brittle after 20–30 years of UV exposure and can crack in hard frosts.
- Cost: £3–£8 per metre for the gutter; £5–£12 for downpipes (per metre)
- Lifespan: 20–40 years depending on quality and UV exposure
- Colour: white is standard; black, grey, and brown widely available; anthracite grey popular for contemporary builds
- Profile: half-round, square/ogee, and deep-flow profiles available
Cast iron
The original material on Victorian and Edwardian properties; still specified for listed buildings and those in conservation areas where uPVC is not permitted. Cast iron guttering is heavy, requires regular painting (every 5–10 years), and is prone to rust and joint failure if maintained poorly. However, a well-maintained cast iron system lasts indefinitely and is significantly more attractive than uPVC.
- Cost: £20–£50 per metre for guttering; £25–£60 per metre for downpipes
- Lifespan: 100+ years with maintenance
- Maintenance: sand and repaint every 5–10 years; re-run hemp-and-mastic joints every 20–30 years
- Weight: considerably heavier — fascia fixings and structural support must be adequate
Aluminium
Aluminium guttering bridges the gap between uPVC and cast iron. It is lightweight, maintenance-free (no painting required), and available in seamless lengths fabricated on-site by specialist contractors — eliminating the joint-leak problem. Powder-coated finishes are available in any RAL colour.
- Cost: £10–£25 per metre for standard sectional aluminium; seamless aluminium £15–£35 per metre (fitted)
- Lifespan: 40–60 years
- Maintenance: virtually none — aluminium does not rust; paint does not peel
Seamless aluminium guttering is an excellent option for large or complex roofs where minimising joints reduces maintenance.
Steel (galvanised or Zincalume)
Used mainly in agricultural and commercial settings but increasingly available for domestic use via specialist suppliers. Powder-coated steel guttering is durable and repairable. Less common than aluminium and cast iron for domestic work.
Material comparison table
| Material | Cost per metre (gutter) | Lifespan | Maintenance | Best for |
|---|---|---|---|---|
| uPVC | £3–£8 | 20–40 years | Low (clean joints) | Standard modern housing |
| Cast iron | £20–£50 | 100+ years | Medium (painting) | Period properties; listed buildings |
| Aluminium (sectional) | £10–£25 | 40–60 years | Very low | Most properties |
| Aluminium (seamless) | £15–£35 (fitted) | 40–60 years | Very low | Long runs; large roofs |
| Steel | £15–£30 | 40–60 years | Low | Contemporary; agricultural |
Gutter Sizes and Outlet Spacing
Gutter sizing is governed by the roof catchment area and local rainfall intensity. BS EN 12056-3 sets out the design method for rainwater drainage. The key principle: the gutter must drain without overflowing under a design storm (typically a 1-in-50-year event for domestic properties, which in the UK is around 75 mm/hour in the South East to 100+ mm/hour in parts of Scotland and Wales).
Standard domestic guttering:
| Profile | Width | Capacity | Typical use |
|---|---|---|---|
| Half-round 75 mm | 75 mm | Low | Flat roofs, extensions, garages |
| Half-round 112 mm | 112 mm | Medium | Standard domestic pitched roofs |
| Deep-flow / Ogee 114 mm | 114 mm | Medium–high | Larger pitches; high rainfall areas |
| Half-round 150 mm | 150 mm | High | Large detached properties; high-pitch roofs |
Outlet spacing (between downpipes) for 112 mm half-round guttering is typically:
- Maximum 12 m between outlets on a level gutter
- Maximum 6 m from a stopped end to an outlet (half-length rule)
Downpipe sizes:
- 63 mm round: for outlets up to approximately 18 m² of roof catchment
- 68 mm round or 65 × 65 mm square: standard domestic — up to approximately 40–50 m² catchment depending on local rainfall
- 110 mm round: large roof areas or high rainfall areas
Getting the downpipe size wrong is one of the most common errors in gutter replacement — simply matching the old size is not always correct if the old system was itself undersized or poorly designed.
Fascia, Soffit, and Guttering Together
Guttering is fixed to the fascia board — the horizontal board running along the eaves below the roof tiles. When replacing guttering, it is sensible (and often necessary) to assess the fascia condition at the same time:
- Timber fascias on houses built before the 1990s are often rotted, particularly at joints, around fixing screws, and behind the guttering where water has tracked back
- Replacing guttering without addressing a rotted fascia results in inadequate fixing and likely gutter sag or fall
- Replacing fascia, soffit, and guttering together costs more upfront but avoids double mobilisation costs — typically £80–£150/metre run for supply and fit of uPVC fascia, soffit, and guttering together, versus £40–£80/metre for guttering alone
Replacement Cost Breakdown
Costs for a typical three-bedroom semi-detached (approximately 30 m of guttering, 3 downpipes of approximately 5 m each):
| Scenario | Labour | Materials | Total |
|---|---|---|---|
| uPVC guttering only (like-for-like) | £250–£450 | £150–£300 | £400–£750 |
| uPVC guttering + downpipes | £300–£550 | £200–£400 | £500–£950 |
| uPVC fascia, soffit, and guttering | £600–£1,000 | £600–£1,200 | £1,200–£2,200 |
| Cast iron guttering only | £500–£900 | £600–£1,500 | £1,100–£2,400 |
| Aluminium (seamless) guttering + downpipes | £400–£700 | £500–£1,000 | £900–£1,700 |
Access costs (scaffolding or cherry picker hire) are a significant variable. For most two-storey semis, access towers or ladder use is sufficient at minimal cost. Three-storey or large detached properties with complex roof lines may require scaffolding at £500–£1,500.
Common Failures and How to Diagnose
| Problem | Likely cause | Fix |
|---|---|---|
| Water dripping at joints | Perished rubber seal | Replace seal or connector (uPVC); re-caulk with gutter sealant |
| Water spilling over front of gutter | Blockage; incorrect fall; undersized gutter | Clear blockage; re-level; upsizing may be required |
| Gutter sagging | Bracket failure; rotten fascia | Replace brackets; replace fascia if rotted |
| Damp internally below eaves | Gutter overflowing or broken joint running on fascia | Clean, repair, or replace guttering; check fascia condition |
| Downpipe not discharging to drain | Blocked underground connection or hopper | Rod drain; clear hopper |
Maintenance Tips
- Clean gutters at least once a year (autumn, after leaf fall) and additionally after any storm — a blocked 112 mm gutter overflows within minutes in heavy rain
- Check joints for weeping each spring — a strip of waterproof gutter sealant is a temporary fix; replacement connectors a permanent one
- Paint cast iron before rust takes hold — once rust has penetrated, sections must be cut out and replaced
- Install gutter guards (mesh or foam inserts) if trees overhang — these reduce the frequency of full cleans but must themselves be checked periodically
