Bay & Bow Windows

Expires: 09/15/2026

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Bay and bow windows are a smart way to boost curb appeal, while expanding interior space and increasing natural light.

At Keystone Window of Pennsylvania, we help homeowners across Southeastern PA navigate the bay window vs bow window decision with clarity and confidence. We install Energy Star®–certified products backed by expert service, transparent pricing, and a transferable lifetime warranty.

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Window Features

Why Homeowners Choose Keystone for Bay and Bow Windows

SuperSeat™ base
Special window seat construction provides excellent R-9 insulation against the cold outside. It is available in white birch, oak, a variety of laminates, Corian®, and custom matching stains and varnish.
Woodgrains
Five interior woodgrains are available so you can match your bay replacement window to your fine furniture.
Comfort-Foam™ insulated
Each mullion and window frame is insulated with Comfort-Foam™ for maximum energy savings and comfort.
Welded Sill Pan
This exclusive feature eliminates water penetration. In addition, the unique design provides a built-in weep system to channel rain away from the window.

Sag-free support
Premium Vinyl Windows bay replacement windows will not sag over time. Our threaded steel rod and chain bracing system securely supports the full weight of the over-hanging window. In situations where a home’s roof comes too close to the bay window to allow use of the rod and chain system, knee brackets are installed.
Style choice
Choose between casement, picture, and double-hung window styles to fill the openings of your bay replacement window.Custom roof system: Order a custom-fitted, painted aluminum or copper roof for your bay replacement window or have your factory-trained installer make a shingled roof to match the roof of your home.

Why Homeowners Choose Keystone for Bay and Bow Windows

We offer upfront pricing with zero hidden fees, so you know exactly what your bay window cost or bow window installation includes.
Our expert installers ensure every window opening is perfectly sealed for lasting comfort and energy efficiency.
Every bay or bow window is backed by a transferable lifetime warranty—protecting your home and investment for years to come.
Rob & Cherie, our founders, have over 20 years of hands-on experience helping Southeastern PA families find the right window solutions—no pushy sales, just results you can see.

Bay Window vs Bow Window: Understanding the Differences

Bay windows consist of three panels—a large center picture window with two angled side windows—offering angular lines and additional interior space. They’re a bold fit for transitional and contemporary designs, often called compass windows due to how they project from the home.

Bow windows, on the other hand, use four or more equal-sized windows joined in a gentle arc. They increase natural light, offer a panoramic view, and are perfect for wider walls or rooms that benefit from a softer, rounded aesthetic.

Frequently Asked Questions

Frequently Asked Questions About Bay and Bow Windows

What Is The Difference Between A Bay Window And A Bow Window?

Bay windows consist of three windows with angled lines, while bow windows feature four or more windows in a gentle curve. Keystone installs both for more light, extra space, and better curb appeal.

How Much Does A Bow Window Cost Compared To A Bay Window?

Bay windows typically cost less than bow windows because they feature fewer panels and more angular lines. Bow windows extend farther from the exterior wall, often using four or more smaller windows to create a curved appearance—adding complexity and installation considerations. Both window types enhance your living space, and Keystone makes it easy to choose the one perfectly suited to your home with transparent pricing and a free in-home consultation.

What Are The Disadvantages Of Bay Windows?

Old bay counterparts were prone to sagging and drafts, but Keystone solves that with sag-free framing and energy-efficient insulation, lowering your heating and cooling costs long term.

What Is Another Name For A Bay Window?

They’re often called projection windows because they push out from the home’s exterior, adding extra space for a cozy reading nook or dining nook, especially when paired with casement windows or other windows.

Are Bow Windows Still In Style?

Absolutely—bow windows feature timeless appeal that suits contemporary home styles, Victorian-style homes, and everything in between. Keystone’s five-lite bow, six-lite bow, and custom options fit various architectural styles and boost your home’s value.

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