The UK's Largest Independent
Building Plastics Manufacturer.
Supporting builders' merchants, roofing distributors, and plumbing suppliers with a full range of UK-manufactured rainwater, drainage, roofline, and cladding systems.
Accredited by Industry Leaders
Total Supply Chain Control
We don't just distribute. We manufacture raw materials, extrude profiles, and deliver using our own fleet. This eliminates third-party delays for your project.
1. In-House Compounding
Since 2012, we have manufactured 100% of our raw materials in Birmingham, ensuring consistent polymer quality and price stability.
2. Advanced Extrusion
Operating 18 energy-efficient extrusion lines and injection moulding facilities. 24/7 production capacity for rapid order fulfillment.
3. Dedicated Logistics
Our private fleet of custom delivery vehicles ensures products arrive on-site in pristine condition, anywhere in the UK & Ireland.
UK's No. 1 Independent Plastics Manufacturer
Scaling to meet the demands of national infrastructure.
The Specification Hub
Installation Guides
Step-by-step installation guides for all product ranges.
Access FilesProduct Brochures
Full range catalogues with technical specifications and colour options.
Access FilesTech Datasheets
Material properties, flow rates, and BBA certifications.
Access FilesNeed Technical Support?
Speak directly to our engineering team regarding your project specs.
Contact SupportCore Building Systems
Rainwater Systems
High-capacity guttering & downpipes for domestic and commercial.
Underground Drainage
Kitemark certified 110mm & 160mm sewer systems.
Roofline
Fascias, soffits & bargeboards in white and colours.
External Cladding
Featheredge, shiplap & double embossed profiles.
Wall Panelling
Waterproof interior panels for bathrooms & kitchens.
Soil & Waste
Push-fit and solvent weld above-ground drainage.
Stock Kalsi Products
Join hundreds of builders merchants and distributors who stock Kalsi — UK-manufactured, Kitemark certified, and backed by a dedicated trade team.