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DuPont DOW Styrofoam XPS Square Edge Extruded Polystyrene Foam Insulation Board 25 psi, 1"–3" x 4 ft x 8 ft, Blue
Regular price $99.68Orders start at $399 — combine any items to reach the minimum. Learn more
DuPont DOW Styrofoam XPS Square Edge Extruded Polystyrene Foam Insulation Board 25 psi, 1"–3" x 4 ft x 8 ft, Blue
DuPont DOW Styrofoam XPS Square Edge is an extruded polystyrene foam insulation board rated at 25 psi, supplied in 4 ft x 8 ft sheets in 1", 2", or 3" thicknesses in blue. The page sells the full line of three thicknesses, each ordered by the piece or per MSF depending on size. Use it for continuous insulation over framing, in cavity walls, roofs, foundations, slabs, attics, and crawl spaces.
Key Features:
- Continuous insulation: Provides continuous insulation over steel stud or wood framing, in masonry cavity walls, conventional roofs, and commercial foundation and floor slab applications.
- Easy to cut: Boards are easy to handle and cut with a utility knife or serrated blade.
- Moisture resistant: Offers superior resistance to water absorption, water vapor transmission, and freeze-thaw cycling.
- Residential and commercial: Suitable for attics, foundations, slabs, and crawl spaces in residential applications as well as commercial uses.
- Durable structures: Contributes to a more durable, sustainable structure.
- Three thicknesses: Available in 1", 2", and 3" thicknesses, each 4 ft x 8 ft and rated 25 psi.
Specifications Table:
| Specification | Details |
|---|---|
| Brand | DuPont |
| Sell unit | 1" sold per MSF; 2" and 3" sold per piece (4 ft x 8 ft board) |
| Product line | DOW Styrofoam XPS Square Edge |
| Material | Extruded polystyrene (XPS) foam |
| Color | Blue |
| Compressive strength | 25 psi |
| Available sizes | 1" x 4' x 8', 2" x 4' x 8', 3" x 4' x 8' |
| Board dimensions | 4 ft x 8 ft sheets |
| Thickness options | 1 in., 2 in., 3 in. |
| Edge profile | Square edge |
| Sell units | 1" sells per MSF; 2" and 3" sell per piece |
| Applications | Continuous insulation over steel or wood framing, masonry cavity walls, conventional roofs, foundations, floor slabs, attics, crawl spaces |
| Cutting | Utility knife or serrated blade |
Coverage & How Much You Need:
Each 4 ft x 8 ft board covers 32 sq ft of wall, roof, or slab area at the selected thickness. Multiply the wall or roof square footage by 1.05–1.10 for waste and divide by 32 to order the right number of boards.
Fit and Compatibility:
Use under any exterior cladding or roofing assembly that calls for continuous XPS insulation, including steel- or wood-framed walls, masonry cavity walls, conventional roofs, and below-grade foundation or slab applications. Tape, flashing, and fastening accessories are sold separately.
Frequently Asked Questions (FAQ):
Q: What is included in one order?
A: One sell unit of the selected variant: the 1" board is sold per MSF, while the 2" and 3" boards are sold per piece.
Q: How much area does one board cover?
A: A 4 ft x 8 ft board covers 32 square feet at the chosen thickness.
Q: How do I cut the boards?
A: The manufacturer states the boards cut easily with a utility knife or serrated blade.
Q: Where can this insulation be used?
A: Over steel or wood framing, in masonry cavity walls, conventional roofs, commercial foundations and floor slabs, plus residential attics, foundations, slabs, and crawl spaces.
Q: Is it moisture resistant?
A: Yes, DuPont states superior resistance to water absorption, water vapor transmission, and freeze-thaw cycling.
Q: Which thickness should I choose?
A: All three sizes share the same 25 psi rating and blue XPS construction, so select thickness based on the R-value or insulation depth your project specifies.
Expert Verdict — Reviewed by the SuperArbor Pro Desk
XPS square-edge board is the go-to choice for continuous exterior insulation because it combines high compressive strength (25 psi here) with low water absorption, making it suitable for both above-grade walls and below-grade slabs. Stagger board joints and tape or seal seams for a continuous thermal layer. Choose 2" or 3" when the project calls for higher R-value per layer; 1" works well for cavity drainage gaps and shallow assemblies.
Cut foam boards with a sharp blade on a flat, stable surface and keep ignition sources away from exposed foam insulation.
Order DuPont DOW Styrofoam XPS Square Edge insulation boards in 1", 2", or 3" thicknesses for your next continuous-insulation project.
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