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Radius, Arched, Round, and Other Special-Shaped Windows

The radius window is one of the most stunning windows we make. With our old-world craftsmanship heritage, ENVIROGUARD™ radius and round windows are an unmatched combination of affordable beauty and dependable durability. With countless size and styling options, our radius, round, arched and specialty-shaped palladium windows are custom made to your specifications–just bring your imagination to the drawing board.   Are you in search of an elliptical, segment, or half-round window?  We make those too.   Our windows are made in the USA and would be a great choice for your next project.

Just like our double-hung windows, we use ENVIROGUARD™ technology for our fixed windows to ensure lasting quality. Precision Millworks’ ENVIROGUARD™ windows are constructed using the highest quality cellular PVC.

20 and 25 year window warranty

Made in the USA

Manufactured with American Pride and Craftsmanship
with USA Made Materials

Configuration and Styling Options

Grille and Grid Light Arrangement

Precision Millworks manufactures custom windows using radius, arched, curved, round, and quarter round profiles in many sizes.  Specialty windows range in sizes up to 10 feet wide.  Nearly any of our standard grid patterns are available to be used on these windows including, colonial, diamond, victorian, gothic, prairie, and ship’s portal. Precision makes radius and arched windows that are historically accurate and can be used in historic renovations and restorations.  We can build any window you can design. Contact any of our qualified dealers to ask about a quote for a custom designed window.

Simulated Divided Light

Achieve improved energy efficiency with while maintaining a timeless appearance with Simulated Divided Light (SDL). SDL grilles are placed on top of the glass and not between the panes of glass. SDL grilles are permanently adhered and are placed on both the interior and exterior sides of the window. The grid/grilles (also know as the muntin pattern) can be applied in virtually any pattern.  If you don’t see the style you’d like in any of our standard configurations shown above, one of our professional dealers can help you create a quote for a custom window design.

Simulated Divided Light Windows
Window Grill Pattern on Radius Window
Application of exterior window muntin
SDL with light filler GBG bar
Muntin Grill Profile, traditional putty glaze look

Putty Glaze Profile

Muntin Grill Profile, traditional style

Traditional Profile

Muntin Grill Profile, square

True Light Filler *

* The true light filler is optional and can be used in combination with the putty glaze or the traditional profiles. This strip is placed inside of the glass (GBG) and fills the light gap between the two muntin bars to give the most accurate representation of true divided light.

Grille Between the Glass

The grille between the glass (GBG) configuration means that the grille is installed between the two panes of glass. By sandwiching the grille between the two panes, this configuration has a classic appearance from a distance, but is an easy to clean option because both the exterior and interior sides are smooth glass.

Interior Muntin Grill Profile, traditional

Traditional Diamond Profile

Muntin Grill Profile, square

Square Profile

True Divided Light

Our custom millwork heritage enables us to create beautiful windows with true divided light (TDL) with putty glaze or insulated glass with wood sticking. If you’ve been dreaming about a custom designed window or simply want a historically accurate window either for a restoration or new construction, contact us today for a custom window quote. TDL windows are single strength glass and made of wood, not PVC like our ENVIROGUARD™ Series of windows. They do not have the same warranty.

Crafted Like the Past, Built to Last

Finishes and Colors


Example of L value scale (LRV)

Windows must be painted for the warranty to be valid–we recommend light paint colors. On the LRV value scale, black = 0 and white = 100, a value of 57 or higher should be used.  Dark paint colors can cause thermal expansion.  Painting with dark paint colors will forfeit the product warranty.  For further information, please refer to the warranty details.

Learn more about painting and care.

ENVIROWOOD™ Stainable PVC Interiors

ENVIROWOOD stainable window with durable PVC

Split Sash

Precision Millworks builds custom windows with a split sash–known also as a wood composite.  The outside of the window is PVC for maximum durability and the inside is natural wood for the aesthetics.  Paint grade or stain grade wood is used. with speciality species including fir, oak, mahogany, and others by request. These or any other custom window must be requested through our quote system. Request a quote for a custom designed window.

Glass Options

LoĒ²-270, LoĒ³-366, with or without Argon fill. Learn about Window Glass Efficiency.

Glass finishes: Tinted glass, obscure glass, tempered glass and other designer glass styles are also available.


With over 20 standard case moulding styles to choose from made out of our ENVIROGUARD™ material, there is an interior casing and exterior brick mould to match almost any architectural style. Our more popular interior casings include 1 x 4 casing with backband and 1 x 6 casing.


ENVIROGUARD Rot proof windows and millwork

Precision Millworks Radius Windows have:

  1. Sloped sill and sill nosing that are made of 100% PVC.
  2. Exterior Brick Mold that is made of 100% PVC.
  3. Insulated glass that improves energy efficiency.
  4. A light commercial rating (134 mph). Coastal versions are available
  5. All of our ENVIROGUARD™ products are paintable*


Radius windows come in many different shapes from round, arched, elliptical, segment, and quarter round. Therefore they also come in many different sizes. There are no real standard sizes for radius windows. We make windows as small as 12-18″ up to multiple feet wide and tall. When pairing a radius window with a fixed/picture windows, the sizes can range beyond 10 feet. Contact your local dealer to configure a quote for your special order radius window. We stand behind all of our ENVIROGUARD™ series windows.

Energy Ratings

The energy efficiency of Precision Millworks windows is independently tested by an outside lab. The results of these tests are reported using an industry standard scale. By using this information, consumers can reliably compare one product with another, and make informed decisions about the windows they buy.For greater comfort, your windows should keep your home cool in the summer and warm in the winter, and keep out the wind and resist condensation.

Super Spacer® Warm Edge 3/4” thick double strength, insulated clear glass with Super Spacer Warm Edge Technology to dramatically minimize energy loss, condensation, and noise.


The HIGHER the better. The higher the R-Value, the better the window conserves thermal energy inside the house. R-Value is a measure for how much resistance there is for thermal energy leaving or entering a home. Windows help preent thermal energy from escaping; therefore, help conserve the energy used to heat or cool a home or commercial building.


The LOWER the better. The lower the U-Factor, the better the window is at keeping heat inside the house. U-factor measures how well a product prevents heat from escaping. The rate of heat loss is indicated in terms of the U-factor (U-value) of a window assembly. U-Factor ratings generally fall between 0.20 and 1.20. The lower the U-value, the greater a window’s resistance to heat flow and the better its insulating value.

Learn more about energy efficiency.


2.1 R Value
.48 U Value


.00061 R Value
1.62 U Value

Rigid PVC

.69-.98 R Value
1.02-1.45 U Value

White Pine

1.3 R Value
.78 U Value


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