3" 4x8 DOW GREY RIGID FOAM BOARD
In-store Pickup
. Ready for Pickup SoonLocal Delivery
Select ZipDescription
Elevate your project's thermal performance with the 3-inch Dow DOWSIL™ (formerly STYROFOAM™) Grey Rigid Foam Board. Engineered for heavy-duty insulation, this high-performance extruded polystyrene (XPS) board is the industry standard for moisture resistance and long-term R-value retention.
Whether you're insulating a basement, a commercial rooftop, or a cold-storage facility, the "Grey" series is designed to handle demanding environments where durability and energy efficiency are non-negotiable.
Key Specifications
| Feature | Details |
|---|---|
| Dimensions | 3" Thick x 4' Wide x 8' Long |
| Material | Extruded Polystyrene (XPS) |
| R-Value | R-15 (at 75°F mean temperature) |
| Compressive Strength | High-load bearing (check specific PSI for your grade) |
| Edge Profile | Square Edge / Tongue & Groove (varies by stock) |
| Color | Grey / Slate |
Why Choose Dow Grey Rigid Foam?
Superior Moisture Management: Unlike expanded "beadboard" (EPS), this XPS foam is closed-cell, meaning it won't absorb water or support mold growth.
High Thermal Mass: With a massive 3-inch thickness, this board provides a robust thermal break, significantly reducing energy costs and preventing "ghosting" on interior walls.
Structural Integrity: Its high compressive strength makes it ideal for use under concrete slabs or in high-traffic roofing applications where it needs to withstand weight without collapsing.
Easy Installation: Despite its thickness, the board is lightweight and scores easily with a utility knife or foam saw for a precise fit.
Common Applications
Foundation & Perimeters: Below-grade waterproofing and insulation.
Commercial Roofing: Under-membrane insulation for flat or tapered roofs.
Radiant Heating: Placed under tubing in concrete floors to drive heat upward.
Cold Storage: Walls and floors of walk-in freezers and coolers.
Pro Tip: When installing, ensure all seams are taped with a high-quality flashing tape to maintain a continuous air and vapor barrier.