Bostik EFA+ Wood Flooring Adhesive & Moisture Barrier – 4 Gallon

Bostik EFA+™ is a professional-grade urethane wood flooring adhesive and moisture-vapor retarder engineered to protect hardwood floors from moisture while delivering a permanently flexible, high-strength bond. It combines adhesive, crack isolation, and moisture control in one system, eliminating the need for separate membranes.

EFA+ is designed to move with wood as it expands and contracts, preventing bond failure, hollow spots, and flooring damage over time  .

Built-In Moisture Protection

EFA+ functions as a moisture-control membrane when applied correctly, blocking harmful vapor emissions from concrete slabs. It protects engineered hardwood flooring on slabs with:

• Up to 15 lbs MVER (ASTM F-1869)
• Up to 87% RH (ASTM F-2170) 

This makes it ideal for humid climate, slab-on-grade construction, and high-risk moisture environments.

Crack-Bridging Anti-Fracture Protection

Bostik EFA+ creates an elastomeric anti-fracture membrane that bridges concrete cracks up to 1/8”, protecting your flooring from slab movement and preventing telegraphing cracks through the wood floor  .

Compatible with Nearly All Wood Flooring

This adhesive works with:

• Solid hardwood
• Engineered hardwood
• Bamboo
• Cork
• Parquet

It also installs over concrete, plywood, OSB, ceramic tile, VCT, terrazzo, cement board, gypsum underlayment, and radiant-heat floors  .

Contractor-Grade Performance

• 1-Part urethane
• Zero water content
• Low VOC (20 g/L)
• 180-minute working time
• Easy troweling with excellent ridge retention
• Elongation over 180%
• Service temperature: –40°F to 150°F 

What Comes in This Pail

• 4 Gallons of Bostik EFA+

Coverage varies by trowel and flooring type (Up to 50 sq ft per gallon for adhesive-only installations; 20–35 sq ft per gallon when used as a moisture barrier) 

Why Installers Choose EFA+

EFA+ eliminates the need for:

• Separate moisture membranes
• Crack isolation layers
• Primers

One application does it all — bond, moisture control, and slab protection — saving time, labor, and money on every job.