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How to Spot Signs & Sources of Window Leaks

We love Arizona monsoons. The clean smells of a rain-washed city and Creosote bushes, happy plants soaking up the bounty of water after a long dry spell, the dense haboob clouds of dirt that require goggles… 😂😂😂 Just kidding on that last one! But a big part of living in Arizona are the torrential rains that monsoon season brings, and it can quickly identify an issue with leaking windows.

But how can you recognize the more subtle signs of a window leak before you have water pouring into a room like Havasu Falls? And how can you distinguish a leak from some other type of problem?

Rosie Certified Partner DunRite Windows has the answers. Here’s a short guide to understanding why your windows leak, where the water is actually coming from, and how to tackle the issue.


Common Culprits of Leaky Windows in Arizona

Cracked or Failing Caulk: Over time, Arizona’s relentless sun can wreak havoc on your window caulk. The watertight sealant dries out, cracks, or loses adhesion, becoming an open invitation for leaks. It’s the most common source, second to dried out sealant in the corners (or mulls where two windows touch) with old aluminum windows.

Condensation Issues: While not technically a leak, condensation buildup on windows can be a telltale sign of improper ventilation or excessive humidity, and blinds or draperies can make evaporation more difficult. This can lead to mold growth and damage.

Tip: Don’t be concerned if you see water in the tracks inside your home. It’s not a leak, it’s how normal drainage functions. However, if it doesn’t drain or overflows, clean out the tracks and weep holes of your windows. Just don’t put towels in the track, please, since that wicks the water out onto your window sill.

Defective Window Glass Seals: Modern double- and triple-pane windows have seals around the edges of the glass panes. These hold the glass in place on the frame, so it’s an essential component. However, they’re also a common troublesome area. These seals can break down due to age, extreme temperatures, or improper installation. This allows our gas insulation to escape, and moisture to seep between the panes of glass, compromising the window’s insulation and potentially leading to water damage inside your home. Condensation you can touch on the glass inside your home is normal, but condensation between the panes where you can’t touch signifies a broken seal.

Roof or Gutter Issues Above the Window:  Sometimes what looks like a window leak has nothing to do with the window. Instead, it’s an issue in the wall or above the window. Replacing or repairing the window won’t help, because it’s not the problem. It might require significant troubleshooting and the help of a contractor to resolve. It may be coming from a roof or siding issue, overflowing gutters rerouting water where it shouldn’t go, or an issue related to construction of the home. It can even be from termite damage or dry rot around the window opening.

Improper Flashing Installation: So what’s the most common cause of window leaks that happens during construction? Stucco, flashing or Tyvek problems where the watertight seal is compromised in some way, showing up years, even decades after a home was built. It’s never good news. Flashing is a thin, waterproof material installed beneath the stucco around your windows. It ties into the window frame and directs water away from the window and prevents it from seeping into your home. Missing or incorrectly installed flashing is a major cause of leaks, especially with older aluminum windows. There can also be issues related to a moisture wrap that doesn’t extend over the window’s nail flange, or siding/stucco that’s been installed correctly. Identifying the source of this type of leak can be very difficult, involving stucco or siding removal, drywall tear-outs and more.

In homes built prior to 1995, no moisture barrier was required. When there is a leak from an unknown location, the stucco itself may be the problem. If you have cracks in your stucco, or your wall soaks up water and changes colors when wet, it’s possible that the exterior surface is no longer watertight.

Similar to roof or gutter issues, replacing the window will not solve this issue. The leak has to be identified and repaired.

Install vs Product Warranties: One thing worth knowing? Arizona requires a minimum two-year installation warranty be included in all replacement window purchases.

If the leak is happening with newly installed windows, naturally you’ll want to contact whomever installed them. Same goes if it coincides with replacing your siding. But if you are less than two years from the window purchase date or you have a longer installation warranty that’s still valid, it’s still worth contacting the installer, even if you’re a new owner of the home.

If it’s outside of that timeframe and it doesn’t look like a seal issue where the product warranty might apply, then you’d want to contact a handyman, or for more complicated leaks, a contractor.

Will Homeowner’s Insurance Cover This? It may cover the repair if it’s related to construction, but not anything related to poor maintenance, neglect or normal wear-and-tear. A leak related to overflowing gutters or an old roof would not be covered.


Diagnosing the Leak Source

Before diving into repairs, it’s crucial to pinpoint the exact location of the leak. Here are some tips to help. Just please keep in mind that you can have more than one source of leaking.

Trace the Water Path: Carefully follow water stains or drips to their origin to understand the source of the leak, and document your findings with as many details and photographs as possible. This helps you identify if the leak is coming from the top, sides, or bottom of the window, or somewhere nearby. How long after a rain does the leaking begin? How long does it continue to drip after it stops raining? Is the water clean or dirty, and what color is it? Is it steady or intermittent? Does the amount of water flowing change as it rains for longer periods of time? These things can tell you how far the leak is traveling, and where it might be coming from.

Inspect the Caulk: Run your finger along the caulk around the window frame. Look for cracks, gaps, or areas where the caulk has pulled away from the window or siding.

Look for crunchy, wrinkled drywall corners in the sill, or softness: This is usually a sign of a slow leak. The drywall paper absorbs small amounts of water and dries crunchy, warped or buckled–or if the amount of water is more significant, leaves the drywall soft to the touch. Signs of inconsistent drywall compared to the rest of the sill and other windows is typically obvious.


Perfect examples of a leaky mull and corner of an old aluminum window.  

Fixing the Leak: DIY or Pro Help?

The appropriate repair approach depends on the severity of the leak and your DIY skills.

Caulk Replacement: Cracked or failing caulk is a relatively simple fix. You can remove the old caulk with a putty knife and apply a fresh bead of high-quality exterior sealant. To ensure your warranty remains valid, be sure to follow the manufacturer’s instructions and remember, proper surface preparation and using the right amount of sealant is key to a long-lasting seal.

Flashing Repair: While some flashing repairs might be manageable for experienced DIYers, extensive flashing issues often require a professional contractor with experience in window installation and waterproofing techniques. If you can safely remove some siding around the window, inspect the flashing for damage, improper installation, or gaps. (Just note that repairing this will only correct the diversion of the water around your window.  The originating problem will still exist and should be corrected.)

Window Seal Repair: Unfortunately, there’s no simple fix for broken window seals. Replacing the entire window unit might be necessary, especially with double-paned windows. This is a job best left to a qualified window replacement company.

Window Frame Repair: If the corner sealant is dry on old aluminum windows, there is also no fix for this. Caulking is temporary at best. Replacing the windows are necessary.

Preventing Leaks: Proactive Maintenance is Key

Regular Caulking Inspection: Once or twice a year, check your window caulking for signs of wear and tear. Reapply caulk promptly if you notice any cracks or gaps. Note all paintable caulking should be painted over for extra U.V. protection.

Proper Ventilation: Ensure proper ventilation in your home to prevent excessive humidity buildup, which can lead to condensation problems.

Trim Your Trees: Overgrown trees and shrubs close to your home can trap moisture around windows and contribute to leaks. Keep your landscaping well-maintained with proper clearance from your exterior walls.

Consistent cleaning. Regularly clean the weep holes and tracks of your window to allow good drainage and smooth operation. Also be sure to keep that glass clean, so the low-E coatings can reflect sun as they’re meant to do. They don’t work nearly as well when they’re dirty.

The Arizona Advantage: Hiring a Local Window Specialist

Arizona’s unique climate demands expertise when dealing with window issues. Hiring a local window specialist with experience in our harsh sun and monsoon seasons offers several advantages:

  • Familiarity with Local Building Codes: Window installation and repair in Arizona must adhere to specific building codes. Local professionals understand these regulations and ensure your windows meet all safety and energy efficiency standards.
  • Experience with Common Arizona Issues: Local window specialists have dealt with countless leaky window situations arising from Arizona’s specific weather conditions. They can quickly identify the problem and recommend the most effective repair solution.
  • High-Quality Materials: They understand the importance of using materials specifically designed to withstand Arizona’s harsh sun and heat. Even if a particular product is EnergyStar certified, it may not be the best replacement window in terms of energy efficiency or quality. A reputable, local window and doors expert will know.

By taking a proactive approach to window maintenance and partnering with a qualified window specialist, you can keep your Arizona home dry, comfortable, and energy-efficient for years to come.

Bonus Tip: Consider investing in energy-efficient windows when replacing leaky units. These windows offer superior insulation, reducing your energy bills and keeping your home cooler in the summer and warmer in the winter. Additionally, energy-efficient windows come with a low-emissivity (Low-E) coating that reflects solar heat, further reducing your cooling costs and protecting your furniture from sun damage – a significant benefit in the Arizona sun. Contact us to schedule an estimate today if you’d like a quote!



DunRite Windows & Doors is a locally owned and operated family business in Scottsdale, with a solid reputation, incredible customer reviews and competitive pricing on top brands. In addition to being Rosie-certified, they are certified and authorized dealers for multiple manufacturers, including several FGIA Installation Master certified installers on the team, ensuring you the best worksmanship possible. Schedule a quote at their Phoenix showroom or your home, and ask for the Rosie on the House discount today!

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