AP-2400 Silicone Mastic

Product Fast Facts
High-Performance Mastic
Adheres to Wet Surfaces


United Asphalt‘s Armour Proof AP-2400 Silicone Mastic is a one-part, high solids, low VOC silicone elastomeric flashing mastic specifically designed for use in sealing roof penetrations, seams, curbs, flashings and other areas on the roof where water infiltration is possible. It works well on roofs that were previously coated with AP-5200 Silicone Coating. Once cured, this liquid applied silicone mastic provides a durable, seamless, flexible, waterproof membrane that resists lateral movement, shear and will allow for normal expansion and contraction.

Coverage and Drying Time

Brush apply AP-2400 at a rate of 100 linear feet over a seam at 4” wide. Minimum wet mil thickness shall be 40 mils. Normal drying time is 6 hours to touch, tack free in 8-12 hours.

Application Information
Required PSI Spray Rate Gal/Min Coverage Rate Gal/100Sq.Ft. Tip Size
Brush Grade N/A N/A N/A


Surface must be pressure washed clean, free of all loose particles, dirt debris and other contaminants that could inhibit adhesion. Refer to the Armour Proof Coatings Specification for detailed instructions on how to prepare the specific substrate.

Suitable Roof Substrates Use as part of a System
Metal BUR Modified EPDM TPO PVC Concrete Masonry Stucco EIFS

Limitations and Precautions

Avoid contamination in sealed containers. Store away from heat, sources of ignition and incompatibles. Use only in well ventilated areas. Do not inhale vapor or mist. Do not get on skin, in eyes or on clothing.

Available Colors for AP-2400 Silicone Mastic