Verified from the manufacturer’s own documentation · last checked September 18, 2026
| Manufacturer | Pella |
|---|---|
| Series | Impervia |
| Frame material | Pella's proprietary fiberglass, which Pella calls Duracast: a thermoset, five-layer material. Pella states it has displayed superior strength over wood, vinyl, aluminum and wood-plastic composites in tensile and three-point bend tests to ASTM D638 and D790, and that it expands and contracts at close to the same rate as glass |
| Styles / configurations | Double-hung, casement, awning, sliding and picture windows plus special shapes, as listed in Pella's Impervia shop; patio doors are also offered in the line. Special shapes are made from a fiberglass-resin material rather than Duracast, which matters for the warranty |
| Glass options | Dual-pane Low-E with argon; SmartSun and other InsulShield options reported by dealers. Grilles between the glass available |
| U-factor | Not published by Pella as a single range. NFRC-certified values are published per style and glazing option in Pella's technical documentation. A Pella dealer page cites 0.27 for a configuration it sells |
| SHGC | Not published by Pella as a single range. Dealer-cited 0.21 for one configuration. Check the NFRC label of the exact unit quoted |
| VT | Not publicly specified |
| ENERGY STAR | Pella states Impervia products with dual-pane glass offer energy-efficient options that meet or exceed ENERGY STAR guidelines in all 50 states |
| NFRC certification | NFRC-certified performance data is published per style in Pella's Architectural Design Manual |
| Warranty | Per Pella's Impervia limited warranty: a non-transferable Limited Lifetime Warranty on the Duracast material that makes up the frame and rectangular sash parts, against cracking, splitting, corroding and warping, for as long as you own the home; labor included only within two years of the date of sale; on transfer of ownership, or when the buyer stops occupying the home, a transferable 10-year limited warranty replaces it. Special-shape products made from fiberglass-resin carry a transferable 10-year term on non-glass materials. Read the current written warranty before purchase |
| Positioning | Pella's fiberglass line, positioned above its vinyl 250 Series and marketed on strength, narrow sightlines and dimensional stability in extreme climates. Factory powder-coat finish meeting AAMA 624, in five colors, with dual-color frames pairing a white interior with Brown, Tan, Morning Sky Gray or Black exteriors |
| Price position | Not publicly specified |
| Installation | Replacement and new construction; sold through Pella showrooms, the Pella Pro dealer network and the Pella at Lowe's program |
Notes
VT not publicly specified. U-factor and SHGC figures are dealer-cited and configuration specific. The warranty distinction between Duracast rectangular products and fiberglass-resin special shapes is easy to miss and worth checking on a quote
Sources
Pella Impervia shop pages for double-hung and casement (styles, colors, powder-coat finish); Pella Pro Dealer Impervia page (material claims and ASTM test references); Pella Impervia limited warranty document; Pella at Lowe's Impervia page; dealer page for the cited NFRC values