120mm Deep Flow is a high-capacity half-round-style profile for larger roofs and heavy-rainfall areas — it clears roughly twice the water of standard half round.
Key specifications
| Profile | 120mm Deep Flow |
| Gutter width | 120mm |
| Downpipe | 68mm round |
| Flow capacity (level) | 3.80 l/s |
| Bracket spacing | 600–800mm |
Best suited to
- Larger roof areas and long runs
- Heavy-rainfall and exposed locations
- Upgrading an over-running half round system
Fitting notes
Because of the higher capacity and weight when full, space deep flow brackets more tightly at 600–800mm centres.
Fix an extra bracket within 150mm of every union, angle, running outlet and stop end, and lay the gutter to a slight fall of about 3mm per metre (1:350) towards the outlet. Leave the manufacturer's 6–10mm expansion gap at union joints, and space downpipe clips no more than 1.8m apart with support near the top and bottom of the run.
Colours
White, Black, Brown, Grey and Anthracite Grey.
Compatibility
A high-capacity half-round style; match 120mm Deep Flow parts. Broadly aligns with Brett Martin, FloPlast, Hunter, Marley, Osma/Wavin and Polypipe deep-flow systems.
Always confirm the profile before mixing parts — see the gutter compatibility guide.
Size your job
Not sure how much you need? Use our capacity calculator and project estimator to size the system and build a parts list.
Get a Quote
Tell us what you need and our team will get back with trade pricing and availability within 24 hours.
- Trade pricing — we won't be beaten
- Fast quotes — usually within 24 hours
- Collection from any of our 21 UK branches
- Local delivery available