How to Repair Fogged Windows

By Amanda Lutz Updated May 10, 2024

Most homeowners know the feeling of looking out a window only to encounter a fine mist of moisture seemingly lodged between the panes. Fogged windows are a common problem that frequently manifests in thermal windows and insulated double- and triple-pane windows.

Fogged windows not only look unappealing but can also affect energy efficiency. Fortunately, you don’t have to deal with fogged windows forever. This guide will address why windows fog, the most common repair options for foggy windows, and when to consider a whole window replacement.


Why Do Windows Fog?

There are a few reasons why double-pane windows might get fogged up. Failed window seals can cause moisture to accumulate between the panes of glass, becoming an eyesore and requiring homeowners to take action to defog them. Temperature changes can also cause the appearance of fogged windows within the window frame. This is particularly common in areas of high humidity. Fogginess can come and go, depending on weather conditions in your area.

Typically, fogged windows don’t indicate the need for an entire window repair. However, fogging is an indicator that the insulating gas has likely escaped. Whatever the reason why windows fog, you’ll likely want to take quick action to restore them to their usual appearance, either through a do-it-yourself (DIY) job or professional service.


Window Fogging Repair Options

You don’t have to deal with foggy windows or wait for the moisture to evaporate. Any of the options below will address your foggy windows and restore them to their flawless appearance. The option that’s best for you will depend greatly on the severity of the fogging and the overall age and condition of your windows.

When choosing the best option, consider your budget and any recommendations from your window manufacturer. Most modern windows allow some flexibility in treating fogged windows.


Defogging Process

Defogging is the most affordable treatment option and one that many homeowners prefer. Quick and relatively painless, professional defogging usually only takes a few hours. During the process, a contractor or handyman drills holes in the window glass and applies an antifog solution to remove moisture.

They’ll then reseal the holes and add a liquid sealant or variety of caulk to the bottom of the glass. The holes will be resealed, and the process is complete. While defogging is effective, it’s a temporary fix and could require repeating every few years.

Defogging Benefits and Drawbacks

Defogging is the most cost-effective foggy window repair treatment. Whether your home windows are brand-new or slightly older, it tends to be effective, offering instant results that get rid of moist air and condensation buildup. Defogging is also convenient, often taking no more than a few hours.

Defogging isn’t perfect, however. It’s, at best, a temporary fix, and if you live in a high-humidity area, there’s a real possibility you could deal with moisture buildup in your windows again in a year or so. The holes being drilled in your windows might also compromise their integrity.

Expected Results and Costs

Professional defogging is a relatively inexpensive procedure. It usually costs around $150, but the final price depends greatly on your windows’ condition and age, as well as the experience and rates of the contracting company. The window size and the number of panes will also influence the project’s price.


IGU Replacement

IGU replacement is another top-rated option for window defogging. IGU replacement involves removing the old seal from the window and installing a brand-new, factory-sealed unit in the existing frame. You’ll typically get better long-term results from IGU replacement than from defogging.

Measuring for Replacement IGUs

If you plan to replace the IGU yourself, take precise measurements of the frame using a measuring tape or accurate ruler. Take great care to ensure accuracy with this step since the wrong size won’t fit properly on your window, and you’ll have to reorder it to avoid seal failure.

Expected Costs and Warranty

IGU replacements are generally the middle-of-the-road window defogging treatment, since it’s more expensive than defogging but usually less expensive than a full-window replacement. IGU replacement can cost $8 to $50 per square foot.* While this is expensive for many homeowners, IGU replacement often comes with a warranty.

*Cost data via HomeGuide.


Window Replacement

Full window replacement is the most expensive defogging treatment but offers the best and longest-lasting results. If you have older windows, consider new windows anyway. Additionally, the energy efficiency of new windows might offset any higher upfront costs associated with window replacement. 

Most contractors and home improvement experts will recommend new windows as the best treatment if your windows have any damage beyond failed seals. New windows can be pricey, costing $230 to $1,230 per window. However, the IRS and other government organizations offer credits for certain energy-efficient home upgrades, such as new windows.

Choosing Replacement Windows

There are a lot of factors to consider when selecting new windows, such as material, glass package, and energy performance ratings. Here are a few common types of windows:

Talk to your professional window installation company about what window type might be best for you. Consider what suits your budget and home improvement goals, as well as the design and aesthetic of your home. Also, think about whether you want energy-efficient windows. Although they offer significant benefits, they can be more expensive.

Expected Costs and ROI

As we mentioned above, new windows can be expensive. The cost greatly depends on the style and size of the window you choose, as well as the brand and pricing structure of the window manufacturer. It can help to outline a budget before looking at windows so you know how much you’ll be working with.


Our Recommendation

Window fogging can be irritating and unappealing. It can make it hard to see out your windows and even indicate a deeper issue with your window seal or structure. While there are a few reasons behind windows fogging up, it’s an issue that can usually be resolved. 

You can have them professionally defogged, replace the IGU, or do a full window replacement. Each option has a different price point, with defogging being the least costly and full window replacement being the most expensive. Research the costs and requirements of each and talk to a window contractor or handyman to see which option is best for your needs.


How to Repair Fogged Windows FAQ

Can I defog windows myself?

Depending on the underlying issue causing the windows to fog up, you can defog them yourself with the right equipment. Alternatively, you can consider replacing the IGU, which is ideal for windows that have lost their sealant.

Will defogging restore the insulating properties of a window?

While defogging will restore the look of your window, it won’t restore the insulating properties. Since defogging involves drilling small holes in the window glass, it can actually cause some insulating properties to be lost once the process is completed.

Is it worth replacing windows before selling a home?

It’s worth replacing windows before selling a home, especially if the market is hot in your area or you have cracked or broken windows. Replacing windows can enhance your home’s aesthetic appeal and give it energy-efficient benefits, which can help you earn more money from the sale.

How can I prevent window seals from failing?

To prevent window seals from failing, inspect them at least once a year and look for signs of weakening or damage. Avoiding pressure washing your windows when performing exterior cleaning is also wise.