This technical update provides additional guidance on GRP (Glass Reinforced Polyester) roofing requirements. It is important that all workmanship carried out during construction is completed in accordance with the relevant tolerances.
This update discusses the standards that apply to site-applied GRP roofing. The GRP market is very competitive with quality control of products and installation being an issue.
The two main associations that cover roofing and GRP are:
However, neither NFRC nor CGFMA cover site-applied glass fibre roofing.
Preformed GRP sections are adhered in place to form the upstands and trims, the joints of the roof are then sealed. Following this, the GRP sheets are supplied to site and fixed to the roof deck using resin and a catalyst. Once cured the top coat of GRP is then applied.
Products will, for warranty purposes, require an independent third party product approval for the product (e.g., BBA, BRE or similar, or a European Technical Approval (ETA) and must include details of the installation and approved installer system). The system will require to have a minimum life expectancy of at least 15 years. The installation may also require to be tested at completion (i.e. including any external fittings installed such as fall protection devices, air conditioning units, etc.) installed by other contractors after the roof covering is completed.
Testing will be required in the following situations:
1. Large developments (apartments, etc., over three stories in height, including the ground storey)
When the total combined roof/balcony areas exceeds 50m2. In this case, 20% of the roof areas must be tested.
2. Low rise housing (detached/semi-detached/ terraced housing three stories or less in height, including the ground storey)
Roof/balcony areas under 50m2: No testing required except:
Where the project consists of 10 or more properties: one test per ten houses (with a minimum of two tests per site) are required.
3. In addition to above, in all cases:
Testing may be required in the following situations and it will be necessary to identify this at the initial site assessment carried out between the developer and the warranty surveyor:
Recommendations: There are two standards applicable for products/systems requiring warranty approval:
Every care was taken to ensure the information in this article was correct at the time of publication. Guidance provided does not replace the reader’s professional judgement and any construction project should comply with the relevant Building Regulations or applicable technical standards. For the most up to date Premier Guarantee technical guidance please refer to your Risk Management Surveyor and the latest version of the Premier Guarantee Technical Manual.