# The Causes of Seal Failures in Windows

- Link: https://mycoastalwindows.com/the-causes-of-seal-failures-in-windows/
- Published: 2016-02-02T18:43:46-05:00
- Author: Jeremy Wood

**A: **The two most common window issues we see are (1) **drafty windows** and (
2) **[foggy windows](https://www.youtube.com/watch?v=_o88lWgR0pw) or also known 
as seal failures.**

Today we are going to talk about foggy windows. Let me paint a scenario for you.
You wake up in the morning and notice one of your double-pane windows looks a little
foggy. You wipe it off between eating your breakfast, maybe with the sleeve of your
pajamas and it’s still cloudy.

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Perplexed, you try and you open your window (_if it’s not jammed shut_) to clear
the fog, but still the fog remains. Suddenly you realize, _Houston…we have a problem!
So what’s going on? The foggy glass is actually coming from within the two panes
of glass_.

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**While some condensation is normal; it’s not normal when it doesn’t go away.** 
What you need to know is that fogged glass is not only unsightly as you can’t see
clearly out your window, but it means that **your window is not working properly**
anymore and is **costing you money.** Imagine money literally flying out your window!

If you’re also concerned about drafty windows, check out our guide on how to tell
if your windows are drafty.

## So What Happened?

**The insulating factor in the glass has been compromised. **Glass all by itself
is a horrible insulator. A single-pane window has an R-Factor (_the ability to stop
the flow of heat_) of 1 where a standard insulating glass unit has an R-Factor of
about 2. It’s important to know that the R-Factor is greater not because of the 
two panes of glass but because there is space in between the two panes.

Want to increase your R-Factor up to 7 or more? You can add argon or krypton gas
and low-E coatings between the panes! But if you want to know how efficient an entire
window is rather than just the glass itself, you need to look at the U-Value, which
the NFRC (National Fenestration Rating Council) recognizes as the only official 
rating for window efficiency.

In Massachusetts, a window must have a U-Value of 0.32 or lower to earn an Energy
Star rating. For government rebates, the U-Value needs to be .30 or lower. At Coastal
Windows & Exteriors, **our most efficient window is .14.**

## **One Seal vs Two Seals and Spacers **

 * Most high-quality double-pane windows have **two perimeter seals**.
    - The inner seal is manufactured to **resist water, aging, and corrosion**, 
      and the **outer seal adds strength**.
    - Once one seal fails, the second seal will only last so long until it too fails.
      It’s also important to note that some window manufacturers only make windows
      with one seal.** _Winter Tip: Don’t buy windows with one seal._**
 * Typical seals also include a **hollow spacer to keep the panes rigidly spaced**
   with a small bead of moisture-absorbing desiccant to prevent windows from fogging
   up. If a small amount of moisture infiltrates the seal, the desiccant becomes
   saturated and _thus my dear Watson_ moist air starts entering and you have a 
   foggy window or seal failure. A warm-edge spacer lowers the conduction and keeps
   your home warmer. _**Winter Tip: Buy windows with warm edge spacers.** _

## What You May Not Know

 1. **Typical home inspections exclude the identification of failed seals on insulated
    glass.** Why you ask?

 * When a seal failure happens you will see 3 things: nothing _(initial stage because
   the desiccant is doing its job for the most part)_, condensation, or foggy glass.
   So **it’s entirely possible that a home inspector could miss one of these signs.**
   Your custom-made windows are made by the manufacturer to a specific size then
   set into a site-built frame by contractors or you. If they are not installed 
   correctly or they aren’t properly caulked where the seal meets the stops, they
   can be at risk for seal failure. **Check your warranty** to make sure it’s not
   dependent on who installed your windows.
 * When screens are present or you just have really dirty windows, the **seal failure
   isn’t as easily detected.**

## What You Should Do

 * _**Examine your windows and frames** at the beginning of each season. Yep, this
   means you need to clean them.   _
 * You can protect your double-pane windows by **preventing excess moisture from
   forming** by creating good air circulation.

You can determine if a window is covered under warranty by looking at the inside
top or bottom of the window for a sticker which should include the manufacturer 
name so you can determine whether a failed glass unit is still under warranty. There
are **many warranties out there from a few years to lifetime.**

Your **best defense against seal failures** is to** buy a [window with a lifetime warranty](https://mycoastalwindows.com/windows/)**.
If you think you may have seal failures, but aren’t sure, please give us a call 
at **978-304-0495** and we will check out your windows free of charge. **We’re here
to help keep you comfortable no matter the season.**

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