When you are planning a flat roof or you already have one, the issue of lifespan arises very soon. GRP fibreglass is a popular flat roofing material in the UK and rightly so. A fibreglass roof can last 25 to 40 years or even more when properly installed using the appropriate products and materials. However, it is not the material itself that ensures that lifespan. How it is installed, what products are used, and how it is maintained all play a significant part. This blog covers what you can realistically expect from a GRP roof, what shortens that lifespan, and what you can do to protect your investment. What Makes GRP So Durable? Glass Reinforced Polyester is what GRP stands for. The roof is made up of a layer of chopped-strand matting that is saturated with polyester resin and has a gelcoat on top of it. The end product is a hard, waterproof and seamless membrane, which is highly resistant to water intrusion, UV degradation and general weathering when cured. Unlike felt or torch-on systems, a properly laid GRP roof has no seams or joins where water can find its way in. This is one of its biggest advantages in the UK's wet climate. The LRWA's Design Guide for Specifiers says that liquid applied waterproofing systems are now the top choice for flat roofing problems. Their seamless and cold-applied features are major reasons why the roofing industry uses them so much. How Matting Weight Affects Longevity One of the first decisions you make when laying a fibreglass roof is which matting weight to use. Apex stocks both 450gsm and 600gsm GRP roofing kits, and the difference matters. 450gsm is a good choice for roofs that don't get walked on and don't need to hold a lot of weight. If you don't plan to walk on the roof of your shed, porch, or garage very often, this is a cheap option. The 600gsm heavy duty GRP roofing kit is the right solution to anything that requires foot traffic or increased mechanical stress, like balconies, house extensions and flat roofs over living areas. People often use a lighter grade of fibreglass when they should use a heavier one, which leads to roofs failing early. Set the mat's weight to suit its purpose. Fire Performance and Building Regulations If you are carrying out work on a house, garage, or commercial building in England, Building Regulations Approved Document B sets out requirements for roof fire performance. The full guidance is available on GOV.UK. Standard polyester GRP systems do not automatically meet fire classification requirements for all building types. Where fire performance is a requirement, a fire-rated system is necessary. We supply a range of fully fire retardant GRP roofing kits across several product lines including Silverseel, Cure-It, Res-Tec, and Pro 25, all rated to BS476 Part 3. If in doubt about what applies to your project, the Planning Portal is a useful starting point for understanding when building regulations apply to roofing works. What Actually Damages a GRP Roof Over Time A fibreglass roof does not simply wear out. The majority of issues are due to certain, preventable causes: UV Degradation of the Topcoat The topcoat is the gelcoat which covers the fibreglass laminate underneath. The topcoat may chalk or fade or form micro-cracks with years of exposure to UV. This does not imply that the roof has broken but it is an indicator that it needs to be taken care of. Ponding water BS 6229 (the British Standard of flat roofs) advises that flat roofs should have a fall of 1:80 to be effective.Even a good GRP system can be put under pressure when water is left to sit over long periods.It is usually caused by poor deck preparation or improper installation of firring strips. Heat Changes and Bad Design When the temperature changes, fibreglass gets smaller and bigger. If the trims aren't put on correctly at the edges, corners, and upstands, the laminate around the edges may lift or crack when the furniture moves. You can avoid most of these problems by using the right GRP roofing trims and corner pieces in the beginning. Poor Surface Preparation Putting resin on a deck that is wet, dirty, or not primed is a common way for it to separate. If you are going to be working on asphalt or concrete that is already there, you need a special primer. Apex's Primax GRP primer is made to do this, and it works much better in the long run to make things stick better and work better. The Topcoat Refurb Option Many fibreglass roofs that look old or worn are actually still strong. Most of the time, the laminate underneath is still in great shape, only the topcoat has worn away. In these cases, a full replacement is not needed. A GRP complete topcoat refurb kit allows you to sand back the existing surface, apply a fresh topcoat, and restore the roof to a fully weatherproof condition at a fraction of the cost of a new installation. This is one of the most cost-effective maintenance options available for fibreglass roofs and can add another 10 to 15 years of serviceable life. Overlay Systems for Existing Flat Roofs An overlay system can be used when an older flat roof needs more than just a fresh coat of topcoat and re-boarding is not an option. The Ultra-Flex GRP overlay kits are uniquely made to be laid over the existing asphalt, concrete and metal surfaces without stripping and re-boarding the deck. Due to this fact, they are particularly effective in already occupied buildings that have to be disturbed as little as possible. Practical Maintenance Tips Once or twice a year it is a good idea to check your GRP roof, walk around and check the edges and that the trim is even. Besides, clean out gutters of leaves or dirt to allow water to flow. When the topcoat begins to crack or line up in certain areas, be aware of this. It's best to take care of it now instead of waiting. An early fix is approximately an hour.Now, when you neglect it, it is going to become a huge job in the future. Apex has a complete video tutorial centre on all its products, including installation instructions, video tutorials on how to lay a fibreglass roof, and so on. The GRP flat roof will last a long time. With the proper equipment, when it is properly installed, and maintained, it can last long, perhaps 25-40 years Have a question regarding your project? Call the Apex team free on 0800 612 7903.
