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Pella® Impervia® Fiberglass Double-Hung Window


Get windows and doors ready to handle virtually anything life throws at them. Pella Impervia double-hung windows are made from our proprietary fiberglass, the strongest material available for windows and patio doors, engineered for lasting durability.61 Equal sightlines provide a clean, consistent aesthetic and a sloped sill design gives the look of a more-traditional double-hung. With our durable powder-coat finish, your double-hung windows will look great for years — inside and out.

Impervia Double-Hung Window Features

Why Fiberglass?

  • Superior strength with our proprietary fiberglass material61
  • Rot- and corrosion-free
  • Tested for the extremes and suitable for all climates
  • Heavy-duty powder-coat finish, including Black


  • Outstanding resistance to water, wind and outside noise, meeting the rigorous performance requirements of a commercial building43
  • 100x more impact resistant than a leading wood/plastic composite16
  • Tilt-latch to make cleaning easier from the interior
  • Sleek profiles and more glass allow for bold, modern designs in an up-to-date color palette, including Black
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Inside Pella Fiberglass

Pella Impervia windows are created from our exclusive fiberglass formula. A structural mat places rovings in a specific, intricate order to meet our high strength standards. Additional layers of strategically placed rovings are added, then the materials are pulled through a machine, injected with polymer resin and heated. It creates an entirely new, thermoset material which won't break down when exposed to the elements or lose its shape in extreme heat — unlike other materials.

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For the Pros

Pella Impervia Double-Hung Window Specs & Install Details

  • Timeless style and proven performance with unmatched strength and lasting durability
  • Handles the most extreme heat and cold16
  • Interlocking checkrail creates a barrier for air and water infiltration
  • Double-hung windows available in sizes up to 47-1/2” x 79-1/2”
  • Performance class and grade LC30-LC50
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Product Downloads

Options for Pella Impervia Double-Hung Windows

Choosing Your Window


Make a design statement with window combinations. Additional combinations are available. See your Pella sales representative for the complete offering.

For Pros

Combination Design Considerations
  • Create larger, unique combinations, with factory-mulled combinations that help save you time on the jobsite.
  • Integral mullion, tight mullion, 1/2” structural mullion or 1” structural mullion with additional steel reinforcements available.
  • Residential and light commercial solutions designed and tested to ASTM E330 for structural test pressures up to 75PSF (DP50).

Interior Finishes

Pella Impervia fiberglass products have a long-lasting factory powder-coat finish in your choice of three colors. Learn more about interior finishes.


For Pros

  • Pella Impervia products are made from our proprietary fiberglass material, the strongest material for windows, engineered for lasting durability.61
  • Our long-lasting powder-coat finish meets AAMA 624, which is a highly-rated fiberglass coating.
  • Exclusive thermoset material won't expand, warp or sag in summer heat, or shrink and turn brittle in harsh winter conditions.
  • Secondary Secure Vent Lock for extra protection.

Styling Your Window


Pella's cam-action locks are available in today's most popular finishes.


For Pros


These windows are available with a range of hardware finishes to meet most design objectives and budgetary requirements.

  • Block-and-tackle balances.
  • Surface-mounted sash locks.
  • Color-matched or optional finishes.

Grille Patterns

Grilles give the appearance of individual window panes. Pella offers many grille patterns to help enhance your home's architectural style.


Grille Profiles

Grilles-between-the-glass create the classic look of individual windowpanes. Learn more about grille profiles.

3/4" Grilles-Between-the-Glass

Window Enhancements


Flat Screens

Conventional fiberglass screens come standard.

Pella InView™ screens let in 14% more light and are 8% more open for improved airflow compared to conventional fiberglass screens.5

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Pella products are backed by some of the strongest warranties in the business.

Learn more about Pella warranties