Masterboard Joint Sealant 10.5 oz Caulking Tube

Masterboard Joint Sealant is a high-performance, flexible adhesive and waterproof sealant designed for sealing and bonding connections, seams, and penetrations in Masterboard product system assemblies. Engineered with advanced Modified Silane Polymer (MSP) technology, this sealant delivers exceptional strength, adhesion, and long-lasting flexibility, even in wet and alkaline conditions commonly found in bathrooms, wet rooms, and shower systems.

Specifically formulated to work with Masterboard Tile Backer’s extruded polystyrene (XPS) foam core and cementitious coating, this sealant ensures a secure, waterproof connection under thinset tile adhesive installations. Tested and proven for long-term performance, it’s an essential component for professional tile installers and DIY homeowners building or remodeling wet area environments.

Key Features:

• High-strength, durable adhesion that remains permanently flexible in wet and alkaline environments
• Reliable waterproof seal for Masterboard Tile Backers, seams, and prefabricated modules within a complete shower assembly
• Fully interchangeable with wedi® joint sealant, offering installation versatility

Download Masterboard Joint Sealant Brochure