
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.
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 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.
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.

A covered patio in Austin can quickly become an unusable heat trap if three critical design decisions are overlooked. This guide breaks down the right panel type, roof orientation, and ventilation strategy to keep your outdoor space comfortable all summer long. Whether you're building new or fixing an existing cover, these insights from Austin Pro Siding can save you from a costly rebuild.

Out-of-state window companies are marketing energy-efficient windows to Austin homeowners — but most are engineered for colder climates, not Texas heat. The wrong Solar Heat Gain Coefficient (SHGC) can turn your home into a greenhouse and spike your electricity bills by $150 a month. Learn how to spot the problem and what Austin homeowners should demand instead.

Painting in winter presents unique challenges. Here are three essential tips to ensure a flawless finish even when the temperature drops.

A guide to navigating insurance claims and repairs after an Austin hailstorm.
.webp)
How old is your roof? Learn the visual clues that help determine its age and remaining life.

Tens of thousands of Austin-area homes built between 1995 and 2010 were constructed with Thermo-Ply sheathing — a paperboard product that fails catastrophically when exposed to moisture. Learn how to spot the warning signs of hidden wall damage and why the only lasting fix is a full exterior tear-off and proper moisture management system.

Get ready for roofing day with this simple guide. Learn how to protect your property and prepare your family for a smooth installation process.

It’s what’s underneath that counts. Why reusing old underlayment can compromise your new roof.

Avoid leaks and voided warranties. We expose the perils of attempting DIY shingle replacement.

Austin's hard freezes cause door warping, failed weatherstripping, and cracked glass seals that 105-degree summers never produce — and most homeowners misdiagnose the cause. Learn the three failure points that freeze-thaw whiplash creates, how to spot whether your door needs a quick fix or full replacement, and what a quality fiberglass door system does differently. Austin Pro Siding has replaced doors across the metro for over 20 years.