What does Window Seal Failure look like?

window seal failure

Multi-pane Windows and the Seal

On dual-pane and triple-pane windows, there is an insulating seal separating the exterior glass pane from the interior glass pane. Some companies refer to this as the “Super Seal” and others refer to it as the “thermal seal” or simply the “spacer”. The seal is a crucial part of the insulated glass unit or, IGU, which prevents the transfer of thermal energy (either hot or cold) from one pane to the other(s). The airgap between glass panes is one of the main reasons the window has insulating properties. This airgap could be filled with either air or one of the inert gases like argon or krypton for increased insulating properties.

What is Window Seal Failure?

broken window seal in a double-pane window can lead to moisture buildup between the glass panes. Here are some signs to look out for:

  1. Condensation Between Panes: If you notice moisture or fog trapped between the panes of glass, it’s a clear indication of a broken window seal. This may appear as water droplets near the corners at first but over time, it can spread across the entire pane.
  2. Increased Energy Bills: A sudden rise in heating or cooling costs could signal a broken window seal The compromised insulation allows heat transfer, affecting energy efficiency.
  3. Drafts or Temperature Fluctuations: If you feel drafts near the window or notice temperature variations, the seal might be compromised. Sometimes, spiders will build a web at the point of a window leak. It is a good place for them to catch small bugs on their way into your home.
  4. Visible Mold or Staining: Mold or staining along the edges of the windowpane indicates seal damage.
  5. Distorted Windowpanes: Sometimes, the glass panes may appear distorted in the center due to seal failure.

Please note that, in our humid Gulf Coast climate, condensation on the interior or the exterior of the window does not indicate a failed window seal. Only when the moisture is between the glass panes does it indicate a breached seal.

Learn about Window Seals and Everything about Windows from this Video!

What Causes Window Seal Failure?

window seal can fail due to various reasons:

  1. Age: Over time, window seal materials may breakdown, leading to failure.
  2. Extreme Weather: Wind, rain, and temperature fluctuations can damage seals.
  3. Expansion and Contraction: Windows exposed to intense sunlight expand during the day and contract at night. This repeated stress can weaken the seal.
  4. Improper Installation: An inexperienced or careless installer can damage the window seal.
  5. Soil Subsidence: Settling of the house on its foundation can create pressure on the glass panes, compromising the seal.
  6. Chemical Damage: Harsh chemicals used during painting or cleaning can harm the sealant material.
Sealed Insulated Glass windows

Can the Seal on Multi-Pane Windows be Replaced?

Yes, the seal between the panes of dual pane windows can be replaced, but it is a specialized process that typically requires professional assistance. So, while it is possible to replace the seal, it is often more cost-effective and efficient to replace the entire insulated glass unit (IGU) rather than just the seal. This is because the process of replacing the seal is labor-intensive and requires specialized tools and materials.

The much simpler process is to either remove the framed sash from the window frame and have a replacement sash made. Most window manufacturers have serial number on the sash providing them the record they need to re-make the sash. Another method available is to remove the stops around the frame of the sash and have just the integrated glass unit re-built and then re-install it into the sash frame.

If you suspect that the seal on your dual-pane windows is broken (e.g., you notice condensation or fogging between the panes), the professionals at Houston Window Experts can point you in the right direction. It’s possible that you may just need a glass company to replace the IGU instead of the entire window.

double pane
triple pane

How Insulating Glass Units (IGUs) are Manufactured

  1. Glass Cutting: Large sheets of glass are cut to the required sizes for the IGUs.
  2. Cleaning: The glass panes are thoroughly cleaned to ensure there are no contaminants that could affect the seal or the clarity of the glass.
  3. Spacer Application: A spacer, typically made of aluminum or a similar material, is placed around the perimeter of one of the glass panes. This spacer maintains the gap between the panes and often contains a desiccant to absorb moisture.
  4. Assembly: The second pane of glass is placed on top of the spacer, creating a sandwich-like structure with the spacer in between.
  5. Sealing: The edges of the glass panes are sealed with a primary sealant, usually butyl, to create an airtight seal. A secondary sealant, such as silicone or polysulfide, is then applied to provide additional strength and weather resistance.
  6. Gas Filling (Optional): For enhanced insulation, the space between the panes can be filled with an inert gas like argon or krypton. This step is done before the final sealing.
  7. Curing: The assembled IGU is allowed to cure, ensuring that the sealants set properly and the unit becomes airtight.
  8. Quality Control: The finished IGUs undergo rigorous quality control checks to ensure they meet industry standards for insulation, clarity, and durability.

This process results in a durable, energy-efficient window unit that helps in reducing heat transfer and improving the overall insulation of your home.

Do Replacement Windows have a Manufacturer’s Warranty for Seal Failure?

Yes, replacement windows made by reputable manufacturers often come with a warranty. Warranties can vary in length and coverage, but they generally cover defects in materials and workmanship, including seal failures. For example, Marvin has a 10 Year Limited Warranty for defects in material or workmanship. For seals, it’s a 20 year Limited Warranty. Check for details on your specific window manufacturer warranty.

Houston Window Experts only deals with the most respected window manufacturers in the country. In addition to the manufacturers warranty, we guarantee our installation against any defects in the installation process. Call us or complete a request form for details on our processes.

We are the Houston Window Experts! Contact us today for a Free Consultation on how we can help with your window needs. You may also call us directly by dialing 832-900-7024.

Our Services include: Replacement Windows Houston, TX metro area. Houston Window Experts is a privately owned and operated company in Houston TX. For more information about us, please write to info [at] or call our Houston office at (832)900-7024. All material is copyright of Houston Window Experts. Houston, TX.