Factory Showroom
Ringer Windows
205 Mustang Cove
Taylor, TX 76574
(512) 989-7000

Sales Office
7901 Cameron Road
Building 1, Suite 112
Austin, TX 78754


by Sep 7, 2016

Window Condensation & Moisture

Multi-Pane Glass Technology – A Little Science & Real World Scenarios

People often call our shop with questions about window condensation. The types of questions vary so much that I decided it would be a good topic to discuss as part of my “Nuts & Bolts” series about vinyl windows. First, a bit of history and a bit of explanation about the technology!

Anyone who’s ever lived with single pane windows knows that when the temperature drops suddenly, their windows are prone to interior condensation that resembles a waterfall of unwanted moisture inside their homes. This occurs because as the temperature plummets, your furnace turns on, pumping out warm moist air. When this warm moist air hits your chilled window, condensation forms. There are other reasons why moisture can form inside your window and we will explore all the possible scenarios and reasons.

For hundreds of centuries windows were comprised of a single pane of glass. For those who might not know, glass is not particularly a good insulator against cold or hot weather but when it’s combined into multiple panes, it becomes much more efficient. As a matter of fact, when a window or door contains dual or triple panes of glass, we call them insulated.

The concept of insulated glass technology began sometime in the mid 1940’s and revolutionized residential windows. Over time, we’ve learned that adding inert dense gasses into the encapsulated space between the panes, such as Argon, boosts the windows efficiency, particularly in winter months.

The technology that physically seals multiple panes of glass together is usually airtight, or hermetic. This part that joins and seals the multi panes of glass is called the Spacer. Over the last 20 years or so, Spacer technology has become very good with tremendous gains in reliability and efficiency. As with most technologies, there are differences in quality levels with insulated glass. The viability and long term effectiveness is directly related to the quality of the Spacer technology AND the application process. Builder grade windows that are mass-produced use very inexpensive Spacer technology with quick & easy application processes, with little regard for post-testing & quality control. Higher quality windows tend use superior Spacer technology that’s manufactured in a computer controlled environment with multiple testing criteria and a much higher quality control. Very few people, including window sales people, know much about this part of window technology!

Over the last decade or so, we’ve seen a surge of triple pane glass usage. Generally speaking, triple pane technology only makes sense in very cold climates. Triple pane glass is more expensive and trickier to produce so it has a higher failure rate than dual pane glass, in general. We’ve run tests on both dual and triple pane glass for our region (Texas) and it simply doesn’t get cold enough to make ANY difference with efficiency levels so we don’t use triple pane. If I were a consumer, it would make sense that more panes of glass would make a better window but it’s simply not true in all cases? Because we are in Texas, where it’s mostly hot and our winters are fairly mild in comparison, it would only add to the cost of the window while providing no additional benefits for our clients.


I’ve discussed single pane windows thoroughly. Simply put, don’t expect much performance from single pane windows!

There are a couple of reasons that multi pane window might exhibit condensation. First, the seals can fail. If a seal fails, moisture gets inside the sealed space, which will be visible and easy to detect over time. Unfortunately, there are no good ways to physically see the broken seal because they are usually micro sized defects. The only way to know that a seal is failed is to visibly see moisture inside the sealed unit. In most cases, failed seals simply produce a foggy look that you can never clean. In more moderate failures, moisture will be visible and trapped inside the space between the panes. With extreme cases, calcium crystals begin to form, which resembles a science project that looks milky white. With Ringer Windows, seal failure is warranted and the glass will be replaced.

I am proud to say that in nearly 10 years, we can report ZERO seal failures. We attribute this to the fact that we only use Cardinal Insulated Glass with their patented stainless steel XL Edge Spacer system. If you really want to learn about glass options and technology, visit their site directly at cardinalcorp.com.

Some folks call us with concerns about moisture on the exterior of their windows, particularly on heavy dew mornings. Insulated glass and replacement windows do not stop condensation from occurring on the exterior side of the glass. This type of condensation typically occurs on a dewy morning, same as it would on a car parked outside overnight. This is 100% normal and O.K. As soon as the humidity level drops and/or the sun comes out, outside moisture burns off and goes away. After a few cycles of heavy dew, it can dirty a window with the atmospheric residue and dust that’s in the water. Unfortunately, there’s nothing anyone can do prevent exterior condensation on a dewy morning.

Condensation can occur on the inside of an insulated window under the right conditions. Interior condensation can happen when interior humidity levels are super high, like in a bathroom with a steamy hot shower. After the super moist air is evacuated, the windows dry off and quickly return to normal.

I will share a true story about condensation and our windows. It wasn’t funny at the time but after we discovered the root cause, even the homeowner got a chuckle from it. It was December and we had just finished installing windows in a clients home. About 2 weeks after we finished, the first really cold snap hit like a ton of bricks. Temperatures plummeted from the mid 50’s into the low 30’s in a matter of hours. Naturally, our client turned on his gas heater to warm his home. After a few hours, he noticed water on all the interior sides of his new Ringer Windows? We were all puzzled, baffled, and shocked! This had NEVER happened, EVER! We dug through every technical manual and looked at every possibility. After a day or so, Mr. Homeowner informed us that his wife had just had their carpeting steam cleaned, but she had not informed him! So, as his heater turned on, it warmed-up his moist carpet, creating artificially high humidity levels in his home. So, after a few days as the carpet dried, his interior condensation stopped and never returned.

If anyone has questions about condensation or ANYTHING about windows, please call our shop and ask for me directly!