Fibre Reinforced Bitumen Waterproof Roof Paint

Wetterflex BG Flexible Roof Coating Paint

An instant repair brush-grade flexible roof paint designed for providing roofs with an immediate waterproof coating.
  • Forms an ultra tough, seamless, flexible layer for repairing light damage to roofs
  • Can be used in commercial, industrial and domestic flat roofs that need general maintenance and patching
  • Only one coat required
  • Adheres to virtually any surface
  • UV resistant
  • Extremely easy to use
  • Long lasting
  • Can be applied when you need it most – when it's leaking!

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Wetterflex BG Flexible Roof Coating Paint


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  1.    This itemWetterflex BG Flexible Roof Coating Paint



Typical Uses:

Primarily designed for flat or pitched roofs. Also used to repair leaking valley and box-section gutters, glass/fibreglass roof lights and lead/zinc flashings.

Wetterflex BG is a brush-applied waterproof roof coating consisting of modified bitumens, mineral fillers, water-displacing agent and a specialist polymer. Wetterflex BG retains its flexibility to achieve exceptional adhesive strength to all roofing materials.

It may be applied in dry or wet conditions, during heavy rain or even under water, and is impermeable to water immediately after application.



Number of parts:1
Application Temperature:5oC to 30oC
Curing Time:Between 24 and 72 hours
Coverage:1m2 per litre
Storage:Up to 24 months
Number of coats:1

Please consult the technical data sheet for full technical product data.

View FileWetterflex DL Technisches Datenblatt    Size: (255.48 KB) View FileWetterflex BG Safety Data Sheet    Size: (145.38 KB) View FileWetterflex BG Technical Data Sheet    Size: (336.67 KB)


Thorough substrate preparation is essential.
All necessary remedial repair work should be carried out prior to application of the coating and the prepared surface should be clean, sound and free of flaking or loose material, moss or fungal growth.
Due to the wide variation in roofing materials and conditions, the following are generalised recommendations only. Please contact the Polycote technical helpline if more specific guidance is required for your application.
Moss, lichen and fungal growth – remove by stiff broom or jet washing, then treat the area with Polycote Destroy IT to inhibit further growth – see our relevant Data Sheet.
Porous surfaces – seal first with Polycote Roof Primer – see relevant Data Sheet.
Asphalt, bitumen and felt roofs – Remove all chippings. Blisters in asphalt can generally be left in place. Blisters in felt – should be cross cut, opened up and re-fixed using Wetterflex BG.
New asphalt and bitumen – surfaces should be allowed to weather prior to application.
Metal surfaces – remove all loose and flaking rust and treat with Polycote Rustex – refer to the relevant Data Sheet. New galvanised steel should be allowed to weather, or may be treated with a suitable primer – please contact the Polycote technical helpline.
Gaps, cracks, joints and holes – Wetterflex BG will fill or bridge small cracks up to approximately 1-2mm wide.
The use of Polycote Flexible Membrane is recommended – see 'Application'.
Wide cracks or joints – should be raked clean, opened out and filled using Wetterflex TG (Trowel Grade) followed by the Flexible Membrane procedure.

To assist application in cold weather, store the material in a warm room overnight prior to use.
Stir thoroughly before use.
Having fully prepared the surface, first fill all gaps, cracks, joints and holes with Wetterflex BG, or Wetterflex TG if wider than 3mm.
Polycote Flexible Membrane should be used to reinforce repairs over any cracks or joints that are subject to movement. The membrane should be cut to approximately 100mm wide strips of appropriate length and laid into the Wetterflex over the cracks immediately, stippling with a paintbrush to integrate the membrane into the wet coating.
After all necessary membranes are embedded, an overall coating may be applied by brush. If this is done immediately, care should be taken when over-coating the placed membranes to avoid disturbing them.
If possible, allow overnight setting of the embedded membranes before over-coating the entire roof surface.
One overall coat is normally sufficient. Further coats may be applied if required, allowing drying intervals between coats.


Product Questions

I used your Wetterflex product recently and have some left over which will be great to have handy if I get another leak. How long will it last?
Question by: Dennis P on 13 Jul 2015 09:14:00
The best way to prolong the life of the remaining product is to put a piece of cling film over the top before securing the lid. Stored correctly, the Wetterflex will last for years.
Answer by: Tom Britchford (Admin) on 20 Jul 2015 17:05:00
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We need to cover an asphalt roof with an area of 32 sq M. How much Polycoat wetterflex would I need?
Question by: Richard Fisher on 18 Sep 2015 08:36:00

Wetterflex BG 25 ltr will cover approximately 25 sq. meters on a smooth substrate so you would be looking at 1 x 25 and 2 x 5ltrs.

However if the asphalt isn't smooth then you may struggle to achieve the coverage's and 2 x 25ltr may work out more effective for you.

Please feel free to contact us and we will be more than happy to help.

Polycote UK
Answer by: Stuart White (Admin) on 18 Sep 2015 09:07:00
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Why might I want to use the Flexible Membrane? What does it do?
Question by: Tom Mornan on 21 Apr 2015 08:22:00
Thanks Tom.

Flexible Membrane gives the Wetterflex added strength and flexibility. It is ideal for cracks and joints, especially when they are over 3mm wide. Simply apply one coat of the Wetterflex, lay the Flexible Membrane in the wet paint and then apply another coat of Wetterflex over the top. We would always recommend it is used over the most vulnerable parts of the roof.

Answer by: Tom Britchford (Admin) on 21 Apr 2015 08:22:00
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Customer Reviews

Absolutely Excellent
Review by DK Floors

The water-proofing material we had off you was absolutely excellent so I thought I would use you again

Very strong - Impressed
Review by Frederic Reed

Over the moon with the product and I am very, very happy. We have been looking for years for a product that works and finally we've found one.

Review by Tom

Hey! This product is great!!! Would use it anywhere there was a leak, even under the kitchen sink! :-)

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