Product Description

Bostik Bituminous Mastic 5L is a heavy-duty, fibre-reinforced waterproofing compound designed for sealing, repairing and protecting a wide range of roofing and construction surfaces. Ideal for both professional and DIY use, this high-performance mastic provides a durable, flexible seal that withstands harsh outdoor conditions.
Formulated as a thick, trowel-grade material, it is suitable for bedding, pointing, filling and sealing cracks or joints. It adheres strongly to a variety of surfaces including mastic asphalt, roofing felt, corrugated and cast iron, fibre cement, slates, lead, copper, zinc, concrete and timber. This versatility makes it an essential product for roof maintenance and general repair work.
Its fibre-reinforced composition enhances strength and durability, while its immediate resistance to rainfall allows application in changing weather conditions. Once applied, it dries to a flexible black coating that remains soft and pliable over time, allowing it to accommodate movement caused by temperature changes without cracking.
Easy to apply and highly reliable, it delivers long-lasting protection against water ingress and weathering, making it ideal for both emergency repairs and planned maintenance projects.
Key Features:
Fibre reinforced for added strength
Immediately resistant to rainfall
Highly weather-resistant finish
Suitable for sealing, filling and repairs
Adheres to a wide range of materials
Flexible, long-lasting waterproof seal
Technical Specifications:
Product type: Bituminous mastic
Brand: Bostik
Size: 2.5L
Application: Trowel application
Suitable surfaces: Asphalt, felt, metal, concrete, timber
Use: Waterproofing, sealing and repairs
Colour: Black
Finish: Flexible, weather-resistant coating