Milgard Ultra Fiberglass Sliding Windows

Milgard Ultra Sliding Windows

Ultra Series fiberglass windows are designed with high-end homes in mind. Ultra fiberglass windows and doors combine the benefits of fiberglass with the style of traditional wood windows. 

Choose sliding windows if you are interested in a ventilating window that can provide more glass surface and more ventilation than traditional single hung or double hung windows. Sliding windows are commonly used near walkways or in tight spaces where they can be opened without being obtrusive. 

  • Fiberglass frame resists swelling, rotting, and warping for long-lasting durability
  • Baked-on finish guarantees an upscale appearance that won't peel or eggshell
  • Designed to match the beauty and profile of wood window products without the maintenance 
  • Custom sizes available in 1/8" increments
  • Milgard Full Lifetime Warranty, including Glass Breakage Coverage

Windows Made in the USA


Ultra™ Series Fiberglass Windows Brochure

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  • Colors
  • Hardware
  • Grids
  • Glass
  • Configurations


  • Frost
  • Harmony
  • Black Bean
  • Bark


  • Frost
  • Sand
  • Harmony
  • Cinnamon
  • Fern
  • Black Bean
  • Bark

High Standards, Quality Finishes

  • Milgard Window and Door Finishes

    As one of the largest and most trusted windows and door manufacturers in the country, Milgard makes sure to only use quality parts and finishes. Every piece of your window or door is held to the highest brand standards.

    To assure quality and long-lasting performance Milgard fiberglass frames are tested for color uniformity, gloss, film thickness, and chemical resistance. 

    Ultra Series
    Ultra Series uses a powder coat finish on Harmony, Bark, and Black Bean when the exterior and interior are the same color. Otherwise, they are painted with a wet coat application.

    Essence Series
    Paint is applied using the latest advances in powder coat finishing technology, it's the same technology used in aerospace and automotive applications. Essence finishes are more durable than conventional finishes and provide increased protection against fading, chipping, and scrapes. 


Hardware Options

  • Cam Lock

  • Sash Pull

  • Positive Action Lock

    The Positive Action lock is offered as an option to the Cam lock/Sash pull.


Grid Options

  • 5/8" Flat
  • 1-1/16" Sculptured
  • Craftsman
  • Legacy
  • 1-1/8" Standard Vintage
  • 3/4" Narrow Vintage

Standard Grids

  • Standard Grids

    – also known as Colonial grids, these are the popular squares that work well in traditional or contemporary styles.  Standard grids can be used on the whole window or door, just on the top sash. You can also specify the number of lites across and up/down, depending on the size of the glass.

Valence Grids

  • Valence Grids

    – Valance grids are similar to the Standard grids but are only across the top of the window or door. Like Standard grids, you can specify the number of lites across and the height. 

Perimeter Grids

  • Perimeter Grids

    – For an attractive contemporary look, consider Perimeter grids which provide an outline on the perimeter of the glass with the grid intersecting in the corners.  Perimeter grids offer an even broader choice of patterns because you can specify a perimeter on each window, on just a sash or a perimeter across an array of windows and/or doors.  You can have the grid intersection only at the top or in all 4 corners.  


Low-E Glass Coatings

  • SunCoat® Low-E2 Glass

    This microscopically thin coating is applied to one side of the glass to reflect heat from its source in the summer, keep heat inside in the winter and reduce harmful UV rays. SunCoat Low-E2 glass comes standard on all Milgard dual-pane windows and patio doors.


    • Consistent temperatures for greater year-round comfort = Energy savings.
    • Reduces harmful UV rays by up to 84 percent = Helping protect fabrics and carpet from the sun's damaging rays.
  • SunCoatMAX® Low-E3 Glass

    SunCoatMAX Low-E glass provides the best clarity and highest performance of all solar gain Low-E glass products.


    • Increases center glass surface temperature in winter = Comfortable, consistently cozy rooms. 
    • Reduces solar heat gain more than two-coat, Low-E glass = Keeps your house cooler in the summer.
    • Provides ultraviolet light blockage = Additional protection from UV-A and UV-B rays for your fabrics and other furnishings.

Obscure Glass

  • Aquatex
  • Cross Reed
  • Narrow Reed
  • Glue Chip
  • Mattelux
  • Rain
  • P516
  • Clear 42

Tinted Glass

  • Solar Bronze
  • Solar Gray
  • Azurelite
  • Evergreen


  • Half Vent
  • Half Vent
  • Half Vent Above 2 Lites
  • Half Vent Below 2 Lites
  • Double Vent Below 3 Lites
  • Half Vent Below
  • Half Vent Below Gable

These windows are so well made. I'm completely happy with them. They were fabricated without a flaw. The sound transmission thru them is so much better than the previous Aluminum sliders. I would definitely recommend these windows to a friend.

— Mattf, Review from

Product Specs

Brand Milgard®
Series Ultra™ Series
Interior Color Frost (with any exterior color), Harmony (with Harmony exterior only), Bark (with Bark exterior only), Black Bean (with Black Bean exterior only)
Exterior Color Frost, Harmony, Bark, Black Bean, Sand, Fern, Cinnamon
Composition Pultruded fiberglass
Construction Type New construction or replacement
Custom Sizes Yes. Available in custom sizes to fit most projects, including replacement.
Sizing Measured in 1/8" increments
Minimum Width 23 1/2"
Maximum Width 71 1/2"
Minimum Height 15 1/2"
Maximum Height 71 1/2"
Frame Depth 4 1/4"
Energy Star Certification Yes
NFRC Ratings Yes
AAMA Certification Yes
Rot Resistant Yes
Glass Warranty Lifetime
Glass Breakage Warranty Yes, Standard
Non-Glass Warranty Lifetime
Labor Warranty Lifetime


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