How to Measure and Order Custom Storm Windows for Historic Homes
Because One Size Definitely Doesn’t Fit All
Introduction: The Storm Before the Calm
If you’ve lovingly restored your original wood windows, the last thing you want is to cover them with something that looks like it belongs on a budget RV. That’s where custom storm windows come in. When properly measured and ordered, they add performance without stealing character. Done wrong? Well… you’ve probably seen it. Storms that rattle, drip, clash with your trim, or worst of all—trap moisture and cause rot.
Let’s walk through how to measure and order custom storm windows for historic homes without sacrificing beauty, breathability, or function. You bring the tape measure—we’ll bring the wisdom.
Why Storm Windows Matter
Storm windows are a preservationist’s secret weapon. Here’s why:
Energy Efficiency: Adds a layer of insulation and air seal.
Glass Protection: Shields delicate historic wavy glass from debris and UV damage.
Noise Reduction: Great for homes near traffic or city centers.
Longevity: Reduces weathering on your restored sash and paint.
And best of all? You don’t have to remove your original windows—making them a win with historic districts and a smart move for sustainability.
Exterior vs. Interior Storms: What’s the Difference?
Exterior Storms (the most common): Mounted on the outside of your window frame. Best for weather protection and visibility of historic profiles.
Interior Storms: Mounted inside, often magnetically. Great when exterior appearances can’t be altered. Want to learn more, check out our Indows window inserts.
In this blog, we’ll focus on exterior storms—especially those that look sharp and perform even better.
Step-by-Step: Measuring for Custom Storm Windows
Before you grab a ladder, here’s what you’ll need:
Tools:
Tape measure (metal, not cloth)
Notepad or measurement sheet
Smartphone (for photos)
Level (for tricky openings)
1. Measure the Opening at 3 Points
You want to capture the actual opening that the storm will sit in. Most manufacturers ask for:
Width: Measure at the top, middle, and bottom. Use the narrowest measurement.
Height: Measure left, center, and right. Use the shortest height.
✅ Pro Tip: Always measure to the nearest 1/16”. A storm that’s too big won’t fit. Too small? You’ll get air leaks—and possible water intrusion.
2. Note the Mounting Surface
There are 3 common mounting conditions:
Blind Stop Mount (most common): Storm sits inside the outer casing, against a stop.
Overlap Mount: Storm overlaps the casing or siding—usually with trim.
Flush Mount: On modernized or flush-jamb homes, like some Craftsman or Mission styles.
Take a photo of each window and note the type of mount. Manufacturers will guide storm build based on this.
3. Confirm Window Type
Are these:
Double-hung (sash moves up/down)?
Single-hung (one fixed, one moving)?
Casement (crank-out)?
Most storms are made for double- or single-hung windows, but casement-style storms can also be custom-fabricated.
4. Count and Label
This is where most people mess up. Label each window location clearly:
“Front Upper Left,” “Dining Room North Window,” etc.
You’ll need this when re-installing and ensuring the right size ends up in the right spot.
Selecting the Right Storm Window Style
2-Track: Fixed top glass, bottom operable sash. Classic and functional.
3-Track: Both sashes move. More airflow but slightly bulkier.
Low-profile Custom Storms: Designed for historic homes. Minimalist frames, invisible fasteners, and sometimes even color-matched to existing trim.
AustinShield™: Our proprietary storm window system that blends performance and aesthetics, available in custom colors and profiles.
Material Options
Aluminum: Paintable and rot-proof. A durable option, but not authentic to historic homes.
Wood Storms: More historically authentic but require light maintenance. However, Austin Historical uses Accoya wood which has a 50-year warranty!
Vinyl: Just don’t. Really. Don't.
Color Matching and Sightlines
A huge part of what makes a storm “invisible” is matching:
Frame color to sash or trim
Proportions and rails to your existing muntins
Using low-profile glazing to reduce reflection
⚠️ Watch out for: White frames on a dark-trim house = instant visual clash.
Ordering From the Right Supplier
Reputable storm window suppliers will take into consideration the historic character of your home, the design of the window, and the materials used to provide the best protection at the best value. Also, it is helpful to have a consultation with on-site measurements to ensure the investment is done right. Austin Historical has Historic Preservation Advisors who can come to your property to consult and measure, and our craftsmen are experienced in making sure the installation is just right so you can benefit from the protection and energy savings.
Final Word
Custom storm windows are like a finely tailored suit—they only look good when they’re made for you. Measuring properly, choosing the right mount and material, and partnering with a preservation-minded supplier makes all the difference.
At Austin Historical, we handle this process from start to finish—whether you’re looking to protect rare crown glass or just want to keep the AC inside where it belongs. Ready for a window that performs like new but looks 100 years old? We’ve got you.
