Fibreglass Flat Roof Restoration on Leaking Roof with Lantern

A Bristol homeowner had been battling persistent leaks on their flat roof, with patch repairs repeatedly failing. Strandek surveyed the roof, identified the failing GRP installation, and installed their fibreglass overlay system — delivering a permanent, seamless fix at a fraction of the cost of a full replacement.

Background and Approach

A homeowner in Bristol contacted Strandek Flat Roofing after experiencing persistent leaks on their flat roof, which featured an integrated lantern. Despite numerous patch repairs carried out by the owner over time, water ingress continued to affect the property.

Following an on-site survey, our team identified that the existing GRP installation was of limited quality and could no longer provide reliable waterproofing. Strandek recommended and installed our proven ‘overlay’ system – a form of repair – as a cost-effective solution to resolve the ongoing issues without the need for a full roof replacement. This approach allowed us to deliver a durable, seamless finish while minimising disruption to the homeowners.

This application note details the tailored installation process, materials used, and performance benefits of the Strandek overlay system for rectifying failed or substandard flat roof installations.

Before & After

The images below show the before and after status of the fibreglass roof. The first 3 show how the roof was pooling water – this was even leaking through into the underlying ceiling, indicating significant water ingress.

Materials and System Description

The project utilised Strandek’s specialist GRP overlay system, specifically designed for application over existing substrates where the original installation has failed.

The system involved thorough surface preparation followed by the application of high-quality polyester resin reinforced with chopped strand mat glass fibre. The installation was completed with a dark grey UV-protective flow coat finish, chosen for its durability and professional appearance.

Strandek’s overlay systems provide a monolithic, joint-free waterproof membrane that is highly resistant to UV degradation, thermal movement, and biological growth. This approach is significantly more cost-effective than full roof replacement — often saving 50% or more — while delivering long-term performance with an expected service life exceeding 30 years.

Installation Procedure

Installation was carried out by Strandek’s certified technicians following comprehensive risk assessments and method statements, with careful attention to protecting the integrated lantern and surrounding areas.

Key Installation Steps:

  1. Surface Preparation: The entire roof was thoroughly power washed to remove dirt, debris, and failed coatings, followed by light sanding to create a clean, keyed surface ready for the new installation.

  2. GRP Overlay Application: A new layer of glass fibre matting was embedded in catalysed polyester resin and built up in layers to form a strong, seamless laminate over the existing substrate.

  3. Finishing: A dark grey UV-protective flow coat was applied to complete the installation, providing both protection and a neat, uniform appearance that integrates well with the lantern detailing.

  4. Quality Assurance: Full curing was allowed, followed by visual inspections and waterproofing verification.

The work was completed efficiently with minimal disruption to the property. Notably, this system can also be applied to valley gutters – a common feature of properties in the South West.

Performance and Benefits

The Strandek fibreglass overlay installation has completely resolved the long-standing issues of rainwater ingress. Key benefits include:

  • Complete Waterproofing: The seamless GRP overlay has eliminated leaks, even during heavy rainfall.

  • Protection of Internal Finishes: Water ingress has been stopped, preventing further deterioration to internal decorations and plasterwork.

  • Cost-Effective Solution: The overlay approach avoided the expense and disruption of a full roof replacement while delivering superior long-term performance.

  • Durability: The new installation provides a robust, low-maintenance roof with excellent resistance to weathering and UV exposure.

The installation is backed by a 10-year FCA-regulated insurance-backed guarantee and a 20-year Strandek workmanship guarantee, giving the homeowners complete peace of mind.

These assurances reflect our proven track record in delivering reliable flat roof solutions across Bristol and the surrounding areas — something we’ve been doing since 1976 and evidenced by our extensive works.

Contact us to find out more or arrange a survey.

Conclusion

This fibreglass flat roof overlay installation in Bristol demonstrates how Strandek’s specialist systems can effectively resolve persistent leaks caused by substandard previous GRP work. By using our proven overlay method with thorough surface preparation and a high-quality dark grey finish, we delivered a permanent, cost-effective solution that has fully protected the property and its internal decorations.

For expert assessment and repair of leaking flat roofs in Bristol, contact Strandek Flat Roofing today.