Our UK weather is notorious for creating issues with our flat roofs. Here at Composite Roof Supplies we want to offer as much help for you as possible. So we strongly advise a pre winter inspection, looks for signs of a potential failure before the bad weather sets in.

What to look for during your 3 Point inspection:

1/ Cracks:

Random sunny days create expansion and slight movement which is perfectly fine under normal circumstances with any Fibreglass Flat Roof. Providing the roofer has built in some allowance for such movement with 10-20mm gaps to perimeter edges & the deck boards were fitted with a 3mm gap on the joints you shouldn’t have any problems.

Unfortunatly cracks may be visible in some GRP Roof installations due to poor preperation when fitting the deck boards.

Fig 1: GRP Crack in the main laminate

crack in grp roof 

Quick Remedial action. 

  • Pu Based products like Tekcryl’s one coat System is a solution that will cover almost any existing surface, a quick fix and can be used in damp conditions so perfect if you missed that pre winter inspection. This product is guaranteed for 5 years. Read More . 
  • GRP Repairs are simple and effective, we advise inspecting the whole roof to see if an expansion joint using the E280 trim should be fitted, if in doubt consult a professional GRP Roofing Company. For small repairs grind out the effected area back to the board then apply some woven bandage with Roofing Resin, blend the new with the old the best you can applying slightly more resin than required prior to sanding back smooth before you apply the Roofing Topcoat. This will achieve a much nicer finish.

2/ GRP Pin Holes:

  • Checking for Pin Holes in GRP roofs! these tiny holes are common if the installer had little or no experience, the misconception is there wasnt enough Topcoat applied, when in actual fact its down to a lack of Resin consolidation during the fibreglassing process. All GRP Roofs should be inspected with a Strip light before any Topcoat is applied, any pin holes need to be reworked with Resin brushed on the laminate. 
Fig 2: GRP PIN HOLES in the main laminate


Remedial action if you spot pin holes after the roof is completed.
  •  Sand the area heavily! ideally back to the clear Resin and re-apply some GRP Roofing Resin ensureing all pin holes are filled, you may need to apply a 2nd coat. Before any NEW topcoat is applied ensure a good wipe down with acetone is done to create a surface for the Topcoat to successfully bond to. Ensure any new Topcaat overlapping the old Topcoat has a keyed surface.
Pin holes grp

3Flashing Checks:


Water entering your property can be disastrous, so prevention is better than cure here. A quick walk around the perimeter edges is advisable, you’re looking for signs of dry cracking in the sealant, sufficient overlaps on joints and no visible cracks in the lead roll.

Check flashings on perimeter edges or capped parapets, Some Lead and PU sealants perish over time with exposer to UV.

 Fig 3: Crack in lead Flashing

Cracks in lead


 Remedial action.

  • Peel out and replace with fresh sealant. Replace any split lengths of Lead roll.
This simple quide to maintaining your flat roof will eliminate to the need for expensive repair work. 
For further technical support we can be contacted via email or Telephone