Product description
Sika Black Jack 903 Bitumen Trowel Mastic 5L – Heavy-Duty Roof Repair & Waterproofing Compound
Take control of roof repairs with Sika Black Jack 903 Bitumen Trowel Mastic, a professional-grade, fibre-reinforced bitumen compound designed for sealing, bonding, and repairing roofs in all weather conditions.
This thick, trowel-applied mastic forms a tough, weatherproof seal immediately after application, even on damp surfaces—making it perfect for urgent repairs where speed and reliability matter.
Key Features & Benefits
- Instant Waterproof Protection – Effective even on damp surfaces for quick repairs
- Fibre-Reinforced Strength – Added fibres improve durability and resistance to cracking
- Heavy-Duty Trowel Grade – Thick consistency ideal for filling gaps, joints, and holes
- Highly Water & Weather Resistant – Withstands rain, frost, and harsh UK conditions
- Semi-Flexible Finish – Remains flexible after curing to accommodate movement
- No Primer Needed (Most Surfaces) – Fast, straightforward application
Ideal Applications
Perfect for a wide range of roofing and maintenance jobs, including:
- Emergency roof leak repairs
- Filling cracks and holes in roofing felt and asphalt
- Sealing gutters, downpipes, and flashing
- Repairs to corrugated iron and metal roofs
- Bonding and sealing joints in roofing systems
Compatible with multiple surfaces including felt, asphalt, lead, zinc, concrete, brick, and metal, making it a versatile solution for trade and DIY use.
Why Choose Black Jack 903 Trowel Mastic?
Unlike standard sealants, Black Jack 903 is built for heavy-duty roofing repairs. Its thick, reinforced formula allows it to bridge gaps, fill deep cracks, and provide long-lasting waterproof protection, even in challenging conditions.
The 5L trade size is ideal for larger jobs or repeat use, delivering excellent coverage while reducing the need for multiple tins.