Schedule Appointment
Austin Pro Calender Icon
Appointment
phone icon
Call Us
Austin Pro Siding, Windows, Roofing, Patio Covers Logo

Sizing Replacement Windows: Key Considerations

By
austin pro
Written by Austin Pro Management
July 22, 2024

Sizing replacement windows bears as much consideration as choosing the materials and comparing energy efficiency ratings. In today’s post, Austin Pro Siding, Windows & Roofing discusses the factors that need to be considered when sizing replacement windows.

Wall Openings

The wall openings are the parts of the exterior wall framing where the windows are anchored to. This is one of the first things a replacement window contractor will take a look at during a consultation. In addition to determining the dimensions of the replacement window frame, the opening’s condition is also determined in case parts require repairs or, if the new window is expected to be heavier, improvements in structural support.

There’s no way to get an exact measure of the actual window opening because it’s hidden behind the window trim — unless the project involves an already-removed window. Window replacement contractors base their window measurements on the window frames and get rough measurements. Generally, the resulting window frames are fractions of an inch smaller than the rough window opening. Resulting gaps between exterior wall and window frame are shimmed and caulked during installation.

Window Style

Window replacement is an opportunity to switch to a different window style. Depending on your chosen style, the new windows may have features that affect the resulting frame and sash sizes. For example, double-hung windows have a counterbalancing mechanism within the frame that makes the sashes easier to lift when opening. Another example is picture windows, which do not have sashes and therefore may need slimmer frames.

Mulling Windows

Mulled windows are essentially two or more windows that are installed in the same opening. Exterior wall framing typically has provisions for window expansion, which means if you have two or more windows alongside each other, chances are the gaps between the windows can be removed to create a bank of mulled windows, or even a single large window.

Austin Pro Siding, Windows & Roofing is one of the most trusted replacement window companies serving communities in Austin. Give us a call at (512) 550-0000 or fill out our contact form to schedule a consultation.

What Actually Happens to Builder-Grade Vinyl Siding When the Austin Heat Hits 105 Degrees
April 4, 2026
What Actually Happens to Builder-Grade Vinyl Siding When the Austin Heat Hits 105 Degrees

Builder-grade vinyl siding wasn't designed for Austin's brutal 105°F summers — and the damage it causes goes far beyond warped panels. From solar heat distortion to hidden mold, learn what's really happening to your home exterior and why local experts consistently recommend James Hardie fiber cement as the lasting solution.

House Wrap FAQ: What You Need to Know
February 28, 2026
House Wrap FAQ: What You Need to Know

What goes under your siding matters. We answer frequently asked questions about house wrap and its role in weatherproofing your home.

The Real Reason We Keep Tearing Out 5-Year-Old Wood Decks in Austin
April 8, 2026
The Real Reason We Keep Tearing Out 5-Year-Old Wood Decks in Austin

Austin's brutal climate — 140°F deck surfaces, sudden floods, and hard freezes — can turn a pressure-treated wood deck into a rotting liability in as little as five years. From hidden joist decay to thousands in recurring maintenance costs, the true price of a wood deck in Central Texas is far higher than most homeowners realize. Discover why Austin contractors and homeowners are making the permanent switch to composite decking.

Boost Your Home's Curb Appeal on a Budget
February 28, 2026
Boost Your Home's Curb Appeal on a Budget

You don't need a fortune to transform your home. Discover cost-effective strategies to enhance your exterior and boost curb appeal instantly.

Siding Trim and Color Inspirations for Stunning Exteriors
February 28, 2026
Siding Trim and Color Inspirations for Stunning Exteriors

Get inspired. We showcase stunning siding trim and color combinations to boost curb appeal.

Board and Batten Siding: The Classic Exterior
February 28, 2026
Board and Batten Siding: The Classic Exterior

Achieve a timeless farmhouse look with board and batten siding. Learn about the history and modern application of this classic vertical style.