What is Dew Point in a Home?

When you hear the term dew point, your mind probably jumps to the weather forecast -- humid days, muggy nights, and sticky skin.

But here's the thing: there's a dew point inside your home, too, and if you're not keeping it in check, it can lead to condensation, mold, and a whole host of uncomfortable (and unhealthy) issues.

At RetroFoam of Michigan, we love talking about building science, and understanding what is dew point and how it behaves in your home is an important part of that.

So, let's break it down.

What is the Dew Point in a Home?

The dew point is the temperature at which air becomes fully saturated with moisture and water vapor begins to condense into a liquid.

In other words, the point where humidity turns into droplets.

Still sounds a bit technical, right? Here's an easy way to picture it.

Imagine you're outside at a summer barbecue, holding an ice-cold pop can. What happens? You start to see little water droplets forming on the outside of the can. That's condensation. The cold can is causing the warm, humid air around it to reach its dew point -- and boom -- water forms.

Now, imagine that same thing happening inside your home.

If you don't have proper insulation, such as walls filled with fiberglass or cellulose, cold air from outside can seep into your home through the walls. Meanwhile, the warm, heated air inside your home (the air you're paying for) meets that incoming cold air, often in the drywall, where condensation can form. 

Over time, this moisture can soak into your insulation and walls, potentially leading to mildew or mold growth.

How to Measure Dew Point at Home

If you're wondering how can I measure dew point accurately at home, the good news is that you don't need to be a meteorologist to figure it out.

Here are a few simple methods:

• Use a digital hygrometer: These inexpensive devices measure humidity and temperature. From there, you can use an online dew point calculator.
• Smart thermostats: Some advanced models track humidity and estimate dew point.
• Infrared temperature guns: These can help identify cold surfaces where condensation might be forming.

If your home feels clammy or you notice condensation on windows or walls, you may already be past the point of needing to measure -- you're seeing signs of high humidity and dew point trouble.

What is a Comfortable Dew Point Inside?

Most people feel comfortable indoors when the dew point is between 40 degrees and 60 degrees, according to the COPD Foundation.

If it climbs higher than that, you may start to feel sticky, your windows may fog up, and you could be headed toward moisture issues behind your walls.

Decreasing Home Dew Point: How to Take Control

So, how do you go about decreasing home dew point and stopping condensation in its tracks?

Start with the building envelope, which is the shell of your home that separates indoors from out. The key is to stop air exchange between warm and cold, which is what creates the dew point in the first place.

Here's how foam insulation helps:

• Air sealing: Injection foam and spray foam insulation create an airtight barrier that keeps outside air from creeping into your home.
• Moisture control: Unlike traditional materials, foam insulation doesn't retain moisture, so it won't become a breeding ground for mold.
• Consistent temperature: With no cold drafts, your interior surfaces stay warmer, reducing the risk of condensation.

Foam insulation helps regulate your home's internal climate and prevent dew point-related problems, all while improving comfort and energy efficiency.

Curious how foam insulation can help reduce moisture issues and make your home more comfortable? Head over to our Learning Center or watch more in-depth science tips on our Foam University YouTube channel.

Key Points:

• What is dew point? It's the temperature at which moisture in the air condenses into water.
• Why does it matter in your home? Dew point issues can cause condensation and mold if warm and cold air meet in your walls.
• What is a comfortable dew point indoors? Around 40 degrees to 60 degrees Fahrenheit.
• How to measure dew point at home? Use a digital hygrometer, smart thermostat, or an IR thermometer with a dew point calculator.
• How to reduce home dew point? Air seal with foam insulation to stop air exchange and regulate indoor temperature and humidity.

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