FAQ

The only surfaces GRflex cannot go onto is EPDM, TPO, Wet Concrete and New Lead.

Most typical roof surfaces, i.e. Felt, Asphalt, Concrete, Metal, Asbestos, Timber, Single-Ply can be over-coated by GRflex. If unsure we would advise to call the GRflex Technical Team.

GRflex Universal Primer is needed for Brickwork, Concrete, Asbestos and Single-Ply. We always recommend the rougher the surface i.e. heavily aggregated felt to use GRflex Universal Primer to help achieve the correct coverage on the BaseCoat.

A smooth surface i.e. Plywood, Asphalt you will achieve the correct coverage of 1.5kg per m². On Heavily Aggregated Felt or Rough Concrete we would recommend to either apply GRflex BaseCoat at a coverage of 1.75kg per m² or fully prime the surface using GRflex Universal Primer at 0.3kg per m².

GRflex Coverage Rates: GRflex Universal Primer @ 0.3kg per m². GRflex BaseCoat @ 1.5kg per m². GRflex TopCoat @ 0.5kg per m².

We have no percentage built in but always recommend adding 10% to materials for this reason. Depends what type of roller the contractor uses, we always recommend short pile as this holds less product.

GRflex Universal Primer – 1.5kg, 3kg. GRflex BaseCoat – 7.5kg, 15kg. GRflex TopCoat – 2.5kg, 7.5kg, 15kg.

Any Joints / vulnerable over 3mm will need to be filled before applying any liquids. If the contractor is unsure of the area addition reinforcement can be added but is not necessary. Fully reinforce the GRflex BaseCoat.

Temperature Limitations are: 0°c – 40°c.

Norbord OSB3 is what GRflex recommend but other timber boards can be used. The guarantee is valid only if the correct GRflex specification is applied.

No they do not require abrading. Smooth surfaces such as PVC, Glass, GRP etc we would always recommend to key up as much as possible.

If the contractor has left expansion gaps between sheets these will need to be filled using Joint Sealer. Any Joint / vulnerable area over 3mm will need to be filled.

If the GRflex has pinholes there is a reason why. We recommend to fill this using PU mastic before over coating with GRflex do not leave for more than 24 hours.

The contractor will need a dry period of at least 20 minutes before applying GRflex. If rain is due within the time do not apply any coatings. If GRflex has cured and it rains this will just need to be clean and dry before applying another coat.

The GRflex Joint Tape is not required. But full reinforcement within the GRflex matting and BaseCoat is required over the trim.

GRflex Reinforcement Matting is supplied in: 1m x 180m rolls. 1m x 25m rolls and the GRflex Joint Tape is 100mm x 25lm or 100mm x 180m.

GRflex Reinforcement Matting is embedded into the GRflex BaseCoat.

GRflex fire rating is AC.

GRflex has a CE.

GRflex has a 25-year life expectancy if applied to the correct specification.

GRflex using a 150gsm Reinforcement Matting.

No this is not necessary but if the existing roof has an expansion joint these will need to be detailed in accordingly.