Bostik BST Wood Flooring Adhesive 4 Gallon – Moisture Vapor Retarder
Description
Bostik BST Wood Flooring Adhesive & Moisture Vapor Retarder
BST is a professional-grade, 1-part urethane wood flooring adhesive and built-in moisture vapor retarder designed for superior bond strength, flexibility, and long-term performance. Engineered for residential and light commercial applications, it delivers reliable moisture control while forming a tough, elastomeric bond that moves with the natural expansion and contraction of wood flooring.
Key Features & Benefits
- Exceptional Green Grab – Minimizes board movement and slipping during installation
- Built-In Moisture Vapor Protection – Reduces moderate moisture vapor transmission through concrete slabs
- Low VOC (22 g/L) – Compliant with SCAQMD Rule 1168
- Elastomeric & Anti-Fracture Performance – Bridges cracks up to 1/8" (3 mm)
- 100% Solvent-Free Formula – Contains no water
- Easy Troweling – Smooth, workable consistency with long open time
- LEED Contribution – May assist in earning EQ 4.1 credits for low-emitting materials
Advanced Moisture Vapor Protection
BST provides moderate moisture vapor control when applied as directed as a membrane system. Suitable for concrete slabs with up to 15 lbs MVER (ASTM F-1869) for engineered hardwood and up to 87% RH (ASTM F-2170). For solid hardwood or bamboo installations over concrete: up to 3 lbs MVER and up to 75% RH. For higher moisture levels, a high-performance moisture reduction system is required prior to installation.
Superior Bond Strength & Flexibility
The elastomeric urethane formula creates a flexible bond that adapts to seasonal humidity and temperature changes. Anti-fracture membrane technology helps bridge substrate cracks up to 1/8", protecting long-term floor integrity.
Approved Flooring Types
- Solid hardwood (adhesive only)
- Engineered hardwood
- Bamboo (adhesive only)
- Cork
- Parquet
- Plywood
- Ceramic tile, marble, and stone inlays (residential/light commercial)
Compatible Substrates
- Concrete
- Plywood and OSB
- Well-bonded vinyl/VCT
- Ceramic tile
- Cement backer board
- Terrazzo
- Cement patch/underlayments
- Gypsum underlayments (dry, above-grade)
- Radiant heat flooring systems
Performance Data
Chemistry Type: 1-Part Urethane
Adhesive Type: Moisture Cure
Color: White
Open/Working Time: Up to 180 minutes
Light Foot Traffic: 6–8 hours
Normal Traffic: 8–12 hours
Water Vapor Permeability: < 0.9
Elongation: > 180%
Service Temperature Range: -40°F to 150°F
Application Temperature: 50°F – 100°F
VOC: 22 g/L
Installation Overview
Can be installed using Wet-Lay Method, Adhesive + Moisture Membrane System, or Adhesive-Only Installation. Proper trowel selection is critical to ensure 100% substrate coverage for moisture protection, >80% transfer for engineered wood, and >95% transfer for solid wood or bamboo. Follow flooring manufacturer recommendations and verify proper substrate preparation.
Packaging & Storage
Available in 4-gallon pails. Shelf life: 1 year in unopened original packaging. Store between 50°F and 100°F.
Ideal Applications
- Residential installations
- Offices and light commercial spaces
- Engineered wood over concrete with moderate moisture levels
- Installations requiring crack-bridging performance
