Pella® Impervia® Fiberglass Casement Window

Pella® Impervia® Fiberglass Casement Window

4.27

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455 Reviews

Mulled

Pella Impervia 3-wide mulled casement windows include three windows of the same size, joined together in the factory. The mulled units ship to you as a combined unit, making installation easier. Fiberglass casement windows are hinged on the side and swing outward to open. The revolutionary Easy-Slide Operator hardware solution allows you to simply slide to open your windows without the effort of cranking.

  • Three fiberglass casement windows combined together side-by-side in the factory.
  • Made from our proprietary fiberglass, the strongest material for windows.32
  • Patented lock system engages multiple locks, with one easy-to-use lock-lever for lasting security.

Configuration: 3-wide

Purchasing Options
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Free In-Home Consultation

Limited appointments available

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There are no showrooms within 200 miles of this location.

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Pella Impervia Casement Window Features

  • Strongest Material for Windows 9

  • Patented Easy-Slide Operator Hardware

  • Enhanced Energy Efficiency

Design Options

Solid-Color Frames

  • black fiberglass frame

    Black

  • brown fiberglass frame

    Brown

  • white fiberglass frame

    White

  • morning sky gray fiberglass frame

    Morning Sky Gray

  • tan fiberglass frame

    Tan

Downloads & Specifications

Design, Performance & Size Tables

Specifications

2D Cross Section

2D Elevation

3D & BIM

Product Literature

  • impervia casement window cob
  • cross section of an impervia casement with the easy slide operator
  • fixed sash and frame impervia window cross sections

Pella Impervia Casement Window Specs & Install Details

  • Unmatched strength and lasting durability for proven performance and sleek style
  • Tested and designed for the extremes
  • Operable casement windows available in sizes up to 37-1/2” x 79-1/2”
  • Fixed casement windows available in sizes up to 71-1/2” x 79-1/2”
  • Performance class and grade LC40-LC50
Frame
  • Overall frame depth is 3-1/4".
  • Nominal wall thickness of Duracast® fiberglass composite members is .050" to .090" thick.
  • Jambs contain factory-drilled installation screw holes on block frame.
Sash

Sash is Duracast fiberglass composite — five-layer pultruded fiberglass material, reinforced with a Pella patented interlocking mat.

Glazing System
  • Quality float glass complying with ASTM C 1036.
  • 11/16" dual-pane insulating glass sealed and bonded to sash.
  • 1" Triple-pane insulating glass sealed and bonded to sash.
  • High altitude glazing available.
Dual Weatherstripping
  • Continuous, flexible ThermoPlastic Vulcanizate material in dual durometer design, compressed between frame and sash for positive seal on all four sides.
  • Secondary ThermoPlastic Vulcanizate leaf-type weatherstrip between edge of sash and frame.
Easy Slide Operator
  • Hardened, nickel-coated Steel worm and wheel gears.
  • Harsh environment approved – ASTM B 117 salt chamber and debris cycling, 20,000 life cycle test approved.
  • 5lb operational forces available on sizes when FW is ≤ 35" and FH is ≤ 72.5" or FW > 35" but ≤ 36" and FH ≤ 60".
Roto Operator Assembly
  • Operator linkage, hinge slide, and hinge arms are 300 series stainless steel.
  • Exposed fasteners are stainless steel.
  • Hardware shall exceed 1,000 hours salt spray exposure per ASTM B 117.
  • Unison Locking System—A single handle locking system operates positive-acting arms that reach out and pull the sash into a locked position

Pella Impervia Reviews

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  • February 25, 2026

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    Why Choose Pella
    Pella was able to perform the additional work required to install the replacement windows.
    Darren D.

  • February 25, 2026

    starstarstarstarstarstar_outlinestar_outlinestar_outlinestar_outlinestar_outline
    Why Choose Pella
    I already have Pella windows and the quote was slightly lower. I liked my sales rep.
    Memorable Aspects
    The installation team was good. They made for a great experience, clean, on time, communicative, did a great job.
    Tracie E.

  • February 23, 2026

    starstarstarstarstarstar_outlinestar_outlinestar_outlinestar_outlinestar_outline
    Why Choose Pella
    Features and cost
    Memorable Aspects
    Very efficient process and great cleanup
    Russell P.
  • See what our customers are saying
    Get honest feedback from real customers who have worked with Pella.
    See All Reviews

Frequently Asked Questions

FAQs about My Product

How long do fiberglass windows last?

There are many factors that affect the actual long-term performance, appearance and functionality of fiberglass windows, but Pella's fiberglass windows are designed for a lifetime of everyday use.

What is the most durable window?

Pella’s proprietary fiberglass is the strongest material for windows, engineered for lasting durability.61 Our exclusive fiberglass will never rot or corrode, and it resists dents, bends and breaks.

Are triple-pane windows worth it?

While triple-pane windows cost a little more than single- and double-pane windows, they offer many benefits. Energy-efficient triple-pane windows help reduce sound and energy costs. Pella triple-pane windows allow for increased energy efficiency while blocking 86 percent of the sun’s ultraviolet rays.

Are fiberglass windows efficient?

Yes, Pella's fiberglass window frames have virtually no expansion and contraction to help improve energy efficiency, reduce the risk for seal failure and provide long-term stability for dependable operation. In addition to the material of the window frame, glass types and coatings also affect the energy efficiency of a window.

Where is a casement window used?

Because casement windows are easy to operate with one hand, they are commonly used in hard-to-reach areas like over a kitchen sink or bathtub. Casement windows are also popular in bedrooms, living rooms and home offices.

FAQs about Purchasing Online

For online orders, what is your policy for returns and products damaged during shipping?

We’re committed to customer satisfaction. If the product you ordered online is damaged during shipping or you do not receive exactly what you ordered, we want to make it right by refunding you in full or sending you a new product. We do not accept returns of undamaged made-to-order products in which a buyer ordered the incorrect size or color, or decided the product was no longer needed. See pella.com/warranty for additional details and exclusions. If you have questions about returns and refunds, please email shop@pella.com.

Who will install the products I ordered?

When you receive your order, you can either install the product on your own with help from our installation kit. Or, hire a Pella Certified Contractor® to take care of installation for you. They are trained and certified to install Pella products.

What’s included in my online window and door purchase?

Product only. When you purchase a window, door or replacement part online, your order will arrive with the product only. Installation is not included. If you need installation parts and accessories, those can be purchased online as well.

How long will it take to receive my online order?

For online orders, a local Pella team member will call within 2-14 weeks to schedule pick up or delivery depending on delivery method and production timing. The time to receive your order varies since all products are made to order based on your specifics.

See All Window FAQs

Awards and Certifications

  • Best Window & Door Product: Easy-Slide Operator

    International Builders' Show, 2021

    Best in Window & Door category for product innovation, functionality, design and consumer friendliness.

  • Best in Show: Easy-Slide Operator

    International Builders' Show, 2021

    Best product in the show, with over 200 entries in six categories.

  • People's Choice winner: Easy-Slide Operator

    Azure Magazine, 2021

    Selected as a favorite by the public in the Architectural Products category.

contemporary dining room with black impervia windows

Pella Impervia

Get windows ready to handle virtually anything life throws at them. Pella Impervia products are made from our proprietary fiberglass, the strongest material for windows.9

Pella’s exclusive fiberglass will never rot or corrode and resists dents, bends and breaks — and the list goes on. With a tough-as-nails powder-coat finish, your windows will never need to be painted or refinished.

Pella Impervia Casement Inspiration

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