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Flash Harry Bitumen Mastic Trowelable Waterproofing Sealer 5 Litre
36 in stock
Fast, tracked courier across South Africa
Unused, in original packaging
Flash Harry Bitumen Mastic Trowelable Waterproofing Sealer 5 Litre is a heavy-duty, trowel-applied compound for sealing roofing defects and repairs. With a built-in membrane, this bulk 5 litre size suits larger roofing jobs and extensive waterproofing across multiple defects and long runs.
Key Features
- Trowel-applied heavy-duty compound for roofing repairs.
- Built-in membrane that removes the need for a separate membrane.
- Versatile sealing of screw bolts, nail holes, sheeting laps, valleys and gutters.
- Solvent-based and effective even when rain is imminent.
- Overcoatable with Alu-Coat Silver in UV-exposed areas.
- Easy cleanup with thinners, solvent or petrol.
- Bulk 5 litre size for larger and repeat roofing work.
Specifications
- Size: 5 Litre
- Type: Trowelable bitumen mastic waterproofing sealer
- Base: Solvent-based
- Membrane: Built-in
- SKU: A10384
- Barcode: 6009691023941
Typical Uses & Applications
- Waterproofing whole roof sections with many fixings to seal.
- Treating long sheeting laps across large corrugated roofs.
- Repairing extensive gutter and valley runs in one job.
- Sealing multiple roof penetrations on industrial and agricultural buildings.
- Ongoing maintenance stock for contractors and property managers.
- Large re-roofing repairs where a bigger volume is needed.
Usage Tip
Clean the area of dust and loose material, then trowel the mastic firmly over the defect, working it into the joint. In UV-exposed areas, overcoat with Alu-Coat Silver for added protection, and clean tools with thinners or solvent. Take fire precautions, as it is flammable when wet.
A dependable, membrane-backed seal sized for bigger roofing jobs.
About FLASH HARRY
Flash Harry offers practical building and waterproofing products aimed at fast, effective repairs for contractors and homeowners alike, formulated for real-world roofing and sealing jobs.
What's in the box:
1 x Flash Harry Bitumen Mastic Trowelable Waterproofing Sealer 5 Litre
| Weight | 4.94 kg |
| SKU | A10384 |
Customer Reviews
Bought this? Share your experience to help other shoppers.
I had leaks for years & used many products recommended. Spent tons of money on "professionals" & still had the roof leaks. Until a friend recommended this product. I bought a 5 litre & was happy with the results. Now buy another 5 litre to finish off other leaks on my roof.




