STH Build

STH Build is a Family run roofing and building company with over 26 years experience. All our teams are Fully qualified tradesmen. Extensions, fibreglass flat roofing specialists, pitched roofing, upvc fascia's & guttering. We manufacture the (Capital Glass Fibre) CGF Board, a structural pre-laminated fibreglass roofing board. The complete service for all your building needs. Contact us today for a free no obligation quotation.


  • 1.Extension Builder
  • 2.Roofer
  • 3.Chimney & Fireplace Specialist
  • 4.Driveway Paver
  • 5.Fascias, Soffits and Guttering Specialist

About STH Build

STH Build are a family run business based in Cardiff with a factory unit in Newport where we manufacture our very own CGF Board.
We carry out various projects in Cardiff, Newport, Bridgend, Swansea and across the whole of South and West Wales.

We are the UK’s leading GRP Fiberglass Flat Roofing specialists, we also undertake Tiled and Slate roofing, Extensions, Garage conversions, Chimney repairs and rebuilds and with associated plumbing and electrical works included.

We manufacture the “CGF Board” a pre-laminated fiberglass osb3 Smart Ply structural roofing board which not only saves time and money but is a substantially higher grade solution and the next generation in fitting a new complete fiberglass flat roofing system.

With over 28 years of vast experience within the construction industry we truly pride ourselves on quality workmanship and have friendly, efficient, professional teams to provide a cost effective solution for all your construction and roofing needs.

We are a “Registered Waste Carrier” company giving all our customers the assurance that their waste is disposed of safely and legally and carry full liability insurance.


City & Guilds Advanced Brickwork