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UK Guttering Profiles & Flow Rates
Half-round, square-line, ogee and deep-flow gutter profiles with sizes, flow capacities and bracket spacing for UK roofing.
Common Gutter Profiles
| Profile | Width (mm) | Flow Capacity (l/s) | Downpipe Size (mm) | Max Roof Area (m²) |
|---|---|---|---|---|
| Mini half-round | 75 | ~0.4 | 50 | ~17 |
| Half-round | 112 | ~0.9 | 68 | ~40 |
| Square-line | 114 | ~1.2 | 65 (square) | ~55 |
| Ogee | 115 | ~1.0 | 68 | ~46 |
| Deep-flow (half-round) | 115 | ~1.5 | 68 | ~68 |
| Industrial/deep-flow | 170 | ~2.8 | 110 | ~130 |
Flow capacities are approximate for a single outlet at one end with standard fall. Central outlet doubles effective capacity.
Downpipe Sizes
| Type | Size (mm) | Compatible Gutters |
|---|---|---|
| Round | 50 | Mini half-round (75 mm) |
| Round | 68 | 112 mm half-round, ogee, deep-flow |
| Square | 65 | Square-line (114 mm) |
| Round | 110 | Industrial / 170 mm gutters |
Material Options
| Material | Typical Lifespan (years) | Bracket Spacing | Notes |
|---|---|---|---|
| PVC (uPVC) | 15–25 | Max 1 m | Cheapest, most common, colours fade |
| Aluminium | 30–50 | 915 mm–1 m | Lightweight, durable, powder-coated |
| Cast iron | 50–100+ | Max 900 mm | Heritage, heavy, needs repainting |
| Zinc / copper | 50–80 | Max 1 m | Premium, patinas naturally, bespoke |
Related Calculators
See the Drainage Pipe Sizes for connecting to underground drainage, or the Rafter Length Calculator for rafter length calculations.
Next up: related pages
Frequently Asked Questions
Half-round is the most common and cheapest profile — suitable for most domestic properties. Square-line has higher flow capacity for the same width and a more modern appearance. Ogee has a decorative moulded front and suits period properties. Deep-flow (high-capacity) is essential for large roof areas or steep pitches. The choice is partly aesthetic and partly functional based on your roof area and rainfall intensity.
The gutter must handle the peak rainwater flow from your roof. Effective roof area = plan area x pitch factor (1.0 for flat, up to 1.4 for steep). For the UK, design rainfall intensity is typically 75 mm/hour. Multiply effective area (m²) by 0.0208 litres/second per m² to get the required flow rate. Then choose a gutter profile with adequate flow capacity. For a typical semi-detached house (50-60 m² roof per side), 112 mm half-round is usually sufficient.
PVC gutter brackets should be spaced at maximum 1 m centres, with additional brackets within 150 mm of each union, angle or stop end. Aluminium guttering is fixed at 915 mm-1 m centres (Marley Alutec installation guides) and cast iron at 900 mm maximum centres (Hargreaves Foundry fixing instructions): despite the rigidity of the material, its weight plus standing water limits the spacing. Running outlets and stop ends should always have a bracket immediately adjacent for support.
Gutters should be installed with a fall of approximately 1:350 (about 3 mm per metre) toward the downpipe outlet. This is shallow enough to be virtually invisible but sufficient to ensure water flows to the outlet. For long gutter runs, the fall can be split by placing the outlet in the centre with falls from each end.
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Last updated: July 2026
Verified against UK standards · estimates only, confirm with your supplier.