Generic APP Bitumen Primer, 20L Solvent-Based Waterproofing Undercoat

APP Bitumen Primer 20L

The Generic APP Bitumen Primer is a high-penetration solvent-based bitumen solution designed to prepare porous surfaces before the installation of torch-on waterproofing membranes. This heavy-duty liquid undercoat seals concrete, masonry, and metal surfaces to ensure a high-strength bond for atactic polypropylene (APP) modified bitumen sheets. It stabilizes dust and fills microscopic voids in the substrate to prevent delamination of the primary waterproofing layer.

Built for the Job

Contractors use this bitumen-based solution on large-scale roofing projects and foundation tanking where structural integrity depends on a moisture-tight seal. It is essential for new concrete decks that require a uniform surface tension to accept heat-fused membranes. The fast-drying formula allows site supervisors to schedule membrane torching shortly after application, reducing downtime in tight construction windows. It performs reliably on both horizontal and vertical planes, making it versatile for parapet walls and retaining structures.

• Priming concrete roof decks before torch-on felt application

• Sealing cementitious screeds and rendered masonry walls

• Corrosion protection for metal gutters and pipe penetrations

Product Highlights

High Substrate Penetration

The low-viscosity formulation ensures the liquid reaches deep into the pores of the concrete to create a mechanical anchor for the waterproofing system.

Rapid Drying Characteristics

• Touch dry in approximately 2 to 4 hours depending on ambient temperature
• Fully cured and ready for torching within 24 hours in standard conditions

Chemical Resistance

This coating resists mild acids, alkalis, and groundwater salts, protecting the structural deck from chemical degradation over time.

Technical Specifications

What’s Included

• 1 x 20L Metal Pail of APP Bitumen Primer

On-Site & Workshop Notes

• Ensure the substrate is completely dry and free from loose debris or oil before applying the liquid coat.

• Store the pails in a cool, well-ventilated area away from direct sunlight and open flames due to the solvent content.

• Do not apply this material if rain is expected within 4 hours to prevent wash-off or emulsification issues.

• Use mineral spirits or white spirits for tool cleaning immediately after use to prevent the bitumen from hardening.