Background and Approach
St Augustine’s of Canterbury Church, located in Downend, Bristol, is a modern Roman Catholic parish church constructed in the mid-20th century with a concrete portal frame, brown brick cladding, and artificial stone dressings. As part of ongoing maintenance to address water ingress and aging roofing issues, Strandek Flat Roofing was contracted to upgrade multiple roof areas.
This project involved the application of Strandek’s GRP (glass-reinforced polyester) systems, specifically an overdeck for the main roof sections and additional work for two smaller annex roofs. Strandek, a specialist in fibreglass since 1976, ensured minimal disruption to church services through flexible scheduling. The upgrades focused on enhancing waterproofing, replacing inadequate flashings, and improving overall durability in the UK’s increasingly wet climate.
This application note details the tailored installation processes, materials, and performance benefits, highlighting GRP’s suitability for historic buildings where longevity and low maintenance are essential.
Materials and System Description
The project utilized two variants of Strandek’s GRP flat roofing systems, selected based on the existing substrates and specific roof conditions:
- STRANDEK Overdeck System: Designed for application over existing surfaces, this includes 18 mm OSB3 interlocking boards mechanically fixed to the substrate, followed by GRP lamination. The system comprises high-quality polyester resin reinforced with chopped strand mat glass fibre, completed with an aesthetic UV protective flow coat.
- STRANDEK Insitu System: An in-situ application directly onto prepared substrates, incorporating specialist primers, GRP laminates, and integrated details such as through-parapet outlets, internal walls, upstands, and custom perimeter trims. Finished with a dark grey flow coat to blend with the church’s stone and brickwork.
Ancillary components included pre-formed GRP flashings to replace unsatisfactory existing lead flashings, new cladding for skylight structures, and updated rainwater goods. The GRP materials provide a seamless, joint-free barrier resistant to UV, biological growth, and thermal expansion, with an expected service life exceeding 30 years (potentially up to 50 years based on system design).
Installation Procedure
Installation was carried out by Strandek’s certified technicians, adhering to industry-recognised standards, with comprehensive risk assessments and method statements. The work was phased to accommodate church services, ensuring no disruptions.
For Roofs A and B (Overdeck):
- Surface Preparation: Initial survey identified suitability for overdecking. Existing surfaces were cleaned and prepared.
- Substrate Enhancement: 18 mm OSB3 8×2 interlocking boards were mechanically fixed to create a stable base.
- GRP Application: Resin primer was applied, followed by glass fibre matting embedded in catalyzed resin, rolled to remove voids, and built up in layers for strength.
- Flashings and Ancillaries: New pre-formed GRP flashings replaced lead ones, addressing inadequate chase depths—a common cause of flat roof failures. Skylight cladding and rainwater goods were installed.
- Finishing: Topcoat applied, with curing and quality checks including visual waterproofing tests.
For Roofs C (In-situ):
- Inspection and Removal: Poorly applied Aquapol finishes and failed seals were laboriously removed to expose the concrete substrate.
- Priming: A specialist primer was applied for optimal adhesion.
- GRP Installation: In-situ lamination incorporated parapet outlets, internal walls, upstands, and custom edge trims.
- Finishing: Dark grey flow coat applied for aesthetic integration, followed by inspections.
The entire project emphasized safety, flexibility, and high-quality workmanship to prevent future issues.
Performance and Benefits
The upgraded roofs have demonstrated superior performance, eliminating water ingress and enhancing structural integrity. Key benefits include:
- Durability and Longevity: GRP’s monolithic design resists leaks, weathering, and maintenance needs, with a projected lifespan of 30+ years.
- Aesthetic and Functional Integration: The dark grey finish on annex roofs complements the church’s architecture, while GRP flashings improve reliability over traditional lead.
- Operational Considerations: Flexible scheduling minimized impact on services, showcasing Strandek’s client-focused approach.
Guarantees include a 10-year FCA-regulated insurance-backed guarantee and a 20-year Strandek workmanship guarantee, providing comprehensive protection against defects.
These assurances reflect the system’s proven track record in similar applications – something we’ve been doing for 50 years.
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Conclusion
The Strandek GRP flat roofing installations at St Augustine’s of Canterbury Church exemplify effective solutions for upgrading ecclesiastical flat roofs, combining durability, minimal disruption, and aesthetic harmony. This project underscores GRP’s advantages for buildings with high usage and heritage considerations. For consultations on similar upgrades, contact Strandek Flat Roofing.