Is It Enough to Just Replace Glass In Window Frames?

Here’s a fairly common question that people ask our installation experts during the in-home consultation: “Can’t I just replace glass in window frames rather than replacing the whole thing?” Often, this is because the homeowner wants the protection of impact-resistant glass but wants to get it done for as little as possible.

The answer is: It depends. Are you replacing glass in an already-impact resistant window where the only damage is to the glass? If the answer is no, then simply opting to replace glass in window sashes rather than doing a whole window replacement might leave you with a less-than-ideal window.

But, why is that? Why should you perform a whole window replacement rather than simply replacing the glass with impact glass in an existing window?

When You Should Replace Glass in Window Sashes

There are a handful of potential situations where only replacing the glass in a window sash will be sufficient to fix your window rather than doing a whole window replacement: 

• When there’s a flaw in the glass from the manufacturer. If it goes unnoticed until after the installation, you may be able to get it replaced under warranty, as the manufacturer can send out a perfect replacement part and have a technician (or a certified partner) replace it with a minimum of fuss.
• If only the glass has been damaged in an impact window. While impact windows are incredibly resistant to breakage from strikes, heavy impacts can still damage one or more layers of glass even if the frame doesn’t get damaged. If only the glass is damaged, you may be able to replace it or the window sash and have your window restored to optimal working condition.

These are two relatively common instances where you can replace glass in windows without having to do a complete tear-out or having to worry about your window’s continuing impact resistance (though a professional should inspect your window in the second case to verify that there’s no damage to your window frame that might compromise its performance).

The reason to do this, especially if the replacement is covered under your window’s warranty, is that it is typically less expensive than buying and installing a new window. 

Reasons to Perform Full Window Replacement Over Just Replacing Glass in Windows

In the majority of cases, complete window replacement will be preferable to simply replacing the glass in an existing window.

There are a few reasons why total replacement is preferable to just changing the glass:

1: Impact Glass Alone Doesn’t Make Windows Impact-Resistant

If your existing window isn’t impact rated, just putting in impact glass won’t make it impact-rated.

This is a major problem for Tampa Bay homeowners since areas along the coast of Florida are frequently exposed to severe weather risks—up to and including hurricanes. A Category 5 hurricane has winds of 157 mph or more.

Using the standard formula for calculating wind pressure—P = 0.00256V², where P is pressure in pounds per square foot (psf) and V is wind speed in miles per hour (mph), a 140 mph wind generates 50.176 psf of force. That’s not even a Cat 5 storm, that’s in the Cat 4 range.

Since 2020, there have been four major hurricanes that came from the Atlantic which were Category 4 at landfall in the U.S. according to NOAA data: Laura (2020, in Texas/Louisiana), Ida (2021, Louisiana), Ian (2022, Florida), and Helene (2024, Florida).

If a window isn’t an impact window rated for more than 50 psf of force, it will fail when subjected to such strong winds. And every part of the window contributes to its impact rating.

If the glass for the window is made to withstand extreme wind pressure and impacts, but the frame it’s set in is only rated for 25 psf of force, the frame will fail during a major storm, 

The glass might hold, but if the frame cracks under the strain, that won’t matter. Water, wind pressure, debris, and more can infiltrate the home, leading to further damage throughout the structure.

2: Replacing the Whole Window Can Improve Energy Efficiency

In addition to providing superior impact resistance, choosing to replace the whole window can let you make other discrete upgrades. For example, you can get vinyl impact windows that have multiple layers of low-e glass with argon gas fills to improve energy efficiency.

Low e glass reflects away harmful and hot infrared and ultraviolet light. This improves the window’s Solar Heat Gain Coefficient (SHGC), or the amount of thermal energy that the window blocks from entering the home. This helps keep your home cool during the hottest summer days, which means that you don’t have to run the air conditioning as hard to remain comfortable.

Argon gas is an inert gas that’s heavier than air, restricting the flow of thermal energy. Window makers can pump it into their double-paned windows to enhance the insulative properties of the window glass, prevent thermal transfer between your house and the outside so it stays cooler in the summer and warmer in the winter.

Vinyl is an extremely energy-efficient window frame material that better insulates your home than metallic window frame materials. 

According to the Engineering Toolbox, depending on the formulation, aluminum can have a thermal conductivity of more than 237W/m K (Watts per meter Kelvin). Meanwhile, polyvinylchloride (PVC, or vinyl) has a thermal conductivity of 0.19W/m K.

In other words, for every watt of thermal energy that vinyl lets into your home, an aluminum window frame will let 1,247.368 watts of thermal energy into your home. That means that vinyl will block far more heat from moving between your house and the outdoors than aluminum will.

3: Impact Window Replacement Meets Florida Building Code Requirements

The Florida Building Code (FBC), sets specific requirements for fenestration (i.e., windows and doors) in homes located in what it defines as Florida’s wind borne debris regions (WBD regions).

WBD regions account for much of the land near the coast—such as the entirety of Clearwater County, most of Hillsborough County, and parts of Pasco County.

If your windows are damaged and need to be replaced, simply swapping non-impact glass with impact glass may not satisfy the requirements of the FBC. In fact, an FBC publication specifically mentions the difference between “Tempered Glass Windows” and “Impact-Resistant Glazing.” According to the document, “When undergoing testing, the window is tested as a unit that includes the glass, frame, attachment hardware, and the installation method.” Impact-resistant glazing might use tempered glass, but tempered glass alone does not make a window an impact window.

If any one aspect of the window is lacking, it won’t meet the standard to be considered valid impact-resistant glazing per the FBC, which may result in a violation. This can translate into stop work orders, fines, and a requirement to replace the whole window again. This just adds cost and delays to getting your windows situated properly.

Doing a whole window replacement with real impact windows bypasses these problems and provides much better protection against hurricanes than deciding to replace glass in windows alone.

4: Insurance Premium Reductions

Another reason to replace an older, non-impact window with an impact-rated window is because it can help you save money on your insurance premiums!

How? There are a couple of reasons.

First, insurance premiums are typically based on risk, as the insurer needs to balance the risk that you’ll need to make a claim against the amount of money they’ll collect from premiums.

Installing impact windows can help reduce the risk of catastrophic damage to your home from hurricanes and other hazards. Because the risk of needing to make a claim is lessened with impact windows, insurers are more willing to offer lower premiums.

Second, Florida Statute 627.0629 requires that “A rate filing for residential property insurance must include actuarially reasonable discounts, credits, or other rate differentials, or appropriate reductions in deductibles, for properties on which fixtures or construction techniques demonstrated to reduce the amount of loss in a windstorm have been installed or implemented.”

In shorter, less legal jargon-y language, if you install impact windows or make any other improvements to your home that reduce the chances of it getting destroyed by hurricanes, insurance companies have to offer some kind of discount on your homeowner’s insurance. Typically, these discounts will be shown on the insurer’s website.

Get Your Impact Window Replacement from the Experts!

If you want to do more than just replace glass in windows and really protect your home against hurricane damage, the hot Florida sun, and more, reach out to Karoly Windows & Doors! We have decades of experience installing impact windows for homeowners throughout Clearwater, Hillsborough, and Pasco County!

Every one of our installations comes backed by our Platinum Standard Lifetime Guarantee, too. If there’s a problem with your new window installation, we’ll fix it for 25 years! If there’s a material problem with the window, that’s covered for 50 years!

Get new windows that bring peace of mind with expert installation by the best team of window pros in Tampa Bay! Book a window consultation today to get started!