A roof repair is one activity that is best undertaken after careful and thorough preparation. There are many types of flat roofing systems, each using different materials and each requiring different methods of repair. In order to approach any repair successfully, it is important to first identify which system you will be carrying out the repair of.

Some common flat roofing systems are:

  • Concrete: This consists of a solid slab of concrete which caps the top of a structure or building
  • Asphalt: This is a bitumen based type of roofing product which has a stone, grey like appearance
  • Felt roofing: This is a more traditional and common method of roofing. Common on old wooden shed structures. The surface finish has a gritty, rough texture like sandpaper. This protective barrier is constructed of layers of bitumen.
  • EDPM: This is a synthetic rubber roofing membrane
  • Fibreglass / GRP Roofing: This is a liquid roofing system which uses Fibreglass Matting, Topcoat and Resin to form a waterproof barrier

For the purpose of this article we will be examining how to repair a Fibreglass or Glass Reinforced Plastic (GRP) flat roof. The steps outlined below are for a standard flat roof repair. If you require further assistance, please contact us or view our FAQ section.

Fibreglass roof repair

Identify damage and required materials

Damage to the laminate manifests in four ways. These consist of tears, holes (or punctures), crushed core laminate or delamination.

Quickly identify if damage has spread beyond these initial damage indicators. Tap the surface of the laminate with a coin to attempt to find any sound changes between solid and crushed laminate.

At this stage it is important to identify the type of resin used during original construction. Any repair carried out to an original roof is a secondary bond. If the roof is constructed using an Epoxy Resin, then it is important to also use Epoxy Resin during the repair process.

Match all repairs as closely as possible to the original build. Once you identify the product type it is time to measure the repair area and choose what type of glass fibre reinforcement that you will require.

Preparing a flat roof for repair

Use a disc sander to clean down the edges of the repair zone and remove any obtrusive damage material, and then clean the area with Acetone. This will remove any obstructions and prepare the area for bonding.

When prepping the repair zone, it is important to remember not sand down past the fibreglass under-layer.

However, we advise sanding an area of 2-3 inches in circumference around the damage so as to key the zone and ensure a good grip for the repair materials to bond to.

Filling in the repair

After completing the prep work it is time to fill the damaged zones. Mix resin and catalyst until the texture and viscosity is that of mayonnaise. Apply this mixture into the repair area, filling above the repair horizon. Then allow to cure.

If scratches or damage is severe and deep add milled fibre to the repair mixture prior to application. This will give it a stronger and thicker consistency.

Once cured, the repair area can be sanded down until level and blended. Now it is time to move on to the next stage, which is applying laminate.

Laminating the damaged areas

Once again, examine the size of the repair area, then pre-cut the glass fibre material into different sized layers. Usually two layers are sufficient. Apply one layer slightly smaller than the repair zone (or sanded zone), then a second which is large enough to cover the entire area that is sanded.

It is now time to mix the polyester resin with catalyst (2%). The catalyst (2%) when mixed through thoroughly at room temperature should allow for a working time of 15 minutes before the mixed product sets, or cures.

Apply the mixed resin to the repair area and then begin to apply the cut layers of glass fibre. Begin with the smaller sized cutting. Once applied, coat with resin using a brush. When no dry patches remain, apply second cutting. This larger cutting will normally be around 20mm larger than the initial repair area. Repeat the process as with first cutting.

After applying resin with a brush and ensuring that both layers are wet through, use a paddle roller to make sure there are no air pockets. Then leave to cure.

When cured, sand the area until uniform and then clean down using Acetone.

Final topcoat layer

Apply a final layer of Topcoat in order to achieve a professional and waterproofed finish. The Advised rate of Topcoat application is 500g/per m2.

Mix the Topcoat with a catalyst at a rate of 2% and applied to the roof with a roller or brush.

Where to buy Fibreglass repair materials

Professional Roofing Fibreglass repair kits

FibreGassDirect offer a complete and comprehensive range of professional Fibreglass repair products.

Our Fibreglass/GRP kits a range of materials, including many of those outlined above. This includes Fibreglass Matting, Lloyds Approved Resin, Topcoat and Tools.

We also offer a range of universal kits which are suitable for a range of repairs including Roofs, Boats, Gutters, and General DIY.

 If you have any questions relating to Fibreglass Roofing materials and its application, please contact our sales team today.