Product Categories

High-Capacity
Rainwater Management

Precision-engineered PVC-U systems designed for the UK climate. Featuring co-extruded high gloss finishes for superior durability and flow rates up to 6.0L/s.

Specification Guides
Made in Britain accredited

Our rainwater systems are manufactured in the UK — Kalsi is a verified Made in Britain manufacturer

Technical Documents Available UV Stabilised Technology Colour-Specific Guarantee Terms High Gloss Finish

Hot weather installation guidance

PVC-U gutters expand and contract with temperature. Correct insertion depth, bracket alignment and expansion gaps help prevent buckling, popped joints and leaks in extreme heat.

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Domestic & Commercial Systems

Select a profile to view components, dimensions, and flow calculations.

All Systems High Capacity Commercial
112mm Half Round
Standard

112mm Half Round

The classic choice for residential properties. Easy clip system with high-flow geometry.

Flow Rate 2.4 L/s
Roof Area Max 114m²
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114mm Square Line
Modern

114mm Square Line

Contemporary profile offering higher capacity than standard round systems. Ideal for new builds.

Flow Rate 3.8 L/s
Roof Area Max 182m²
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115mm Deepflow
High Capacity

115mm Deepflow

Semi-elliptical profile designed for high flow rates. Reduces the number of downpipes required.

Flow Rate 4.8 L/s
Roof Area Max 228m²
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Klassic Ogee
Decorative

Klassic Ogee

Classic 130mm moulded ogee profile with internal/external angles and left/right-hand stopends. Full ogee guttering solution for period properties.

Flow Rate 4.2 L/s
Roof Area Max 200m²
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Krown Ogee
Decorative

Krown Ogee

Distinctive stepped ogee profile with integral fixing wings. High capacity, no corner fittings required — available in Anthracite Grey.

Flow Rate 4.5 L/s
Roof Area Max 215m²
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Kommercial 160
Commercial

Kommercial 160

160mm half round gutter with 110mm downpipe for commercial, industrial, and agricultural buildings. Also known as the 170mm Kommercial Deepflow.

Flow Rate 6.0 L/s
Roof Area Max 315m²
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Kast Iron Half Round
Heritage

Kast Iron Half Round

Traditional half round profile with authentic cast iron effect finish. Ideal for period properties, new builds, refurbishments, and log cabins.

Finish Cast Iron Effect
Colour Black
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Kast Iron Krown Ogee
Heritage

Kast Iron Krown Ogee

Stepped Krown Ogee profile with cast iron effect finish. Heritage ogee guttering aesthetics without the maintenance of genuine cast iron.

Finish Cast Iron Effect
Colour Black
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Installed Across the UK

Our rainwater systems protecting real homes and commercial buildings.

Aquaflow guttering installed in grey
Ogee guttering in black with oak fascia
Professional gutter installation
Ogee guttering in rosewood
Residential guttering installation
Gutter detail close-up
Gutter installation detail
Guttering detail

Need Flow Rate Calculations?

Download our comprehensive Rainwater Technical Guide (PDF), including flow capacity charts for all gutter profiles and downpipe configurations.

Flow Calculator Specification Guides