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Insulation | Does It Help With Humidity?

Most people know insulation helps to keep the air inside and the air outside at different temperatures. However, I recently became curious if this division between the inside and outside of a home included humidity.

After looking into it, I found that insulation doesn’t normally have a huge impact on humidity itself. But it can actually cause an issue to pop up with moisture in the home. As you read, I’ll be explaining what that issue is and whether or not it’s really a big problem.


Insulation does not directly affect humidity. Moisture is carried into and out of a house with airflow. Insulation only stops the movement of heat energy. However, by controlling temperature, insulation can make humidity seem worse or present differently.

Insulation Keeps Temperatures Constant

The primary purpose of insulation is to stop the transfer of heat into and out of the home as materials used to insulate are picked for their poor conductive abilities.

Conduction is the transfer of energy in the form of heat (in this case) from one area to another without any actual movement (of items, air, or liquid).

Insulation is usually made of a lightweight wooly, pellet, or foam-like material placed in between pre-built areas of the home—inside of walls or the attic, for example.

Polyurethane spray foam insulation on the attic

For this reason, it does not greatly impact the flow of air; it mostly just reduces the transfer of heat into and out of a building through these insulated areas.

Since air is what carries humidity, insulation, therefore, does not usually have much effect on overall humidity levels within a home.

Compressing Insulation Reduces the Passage of Air

Although insulation doesn’t generally affect the flow of air, it can have more of an effect on airflow if it has been compressed. 

Once insulation is compressed and condensed, there are fewer passageways for air to move through it freely. 

Since air is again the carrier of humidity, this means humid air will have a harder time entering or leaving the home and, thus, may solve (or worsen, depending on your situation) your humidity problems.

It should be noted, however, that while compressing could improve your humidity issues, it can also worsen your insulation’s ability to perform its primary job of regulating thermal conduction.

If the insulation itself is compressed so that it does not completely fill a gap/space, then it becomes less effective. This is because there is less width to the insulation itself, reducing the distance between the air on the inside and outside of a space.

Alternatively, you may have more insulation than is needed compressed into a space. Past a certain point, “extra” insulation provides little to no additional benefit, making additional amounts of compacted insulation essentially useless.

Insulation Can Increase Condensation

As stated, insulation does not directly impact how much moisture exists inside a house or room.

However, it can certainly affect the temperature inside your home, as this is again its primary purpose, and temperature can affect how much moisture is suspended in the air as water vapor and how much settles onto surfaces as condensation.

Let’s say you live in an area with hot, muggy summers, and the air in your home is also humid as a result, but you have insulation installed to help keep the interior of your home cool

As a result, the humidity in your air may condense into liquid form and settle on various surfaces without heat to keep it suspended in the air.

Illustration of a cold air and a hot air and the moisture that it can hold

This is because cold air cannot “hold” as much moisture as warm air. Heat is a form of fast-moving energy, and water vapor at hotter temperatures is far less likely to condense. However, as the temperature cools and water loses energy, it becomes more likely to condense.

In other words, while insulation will not greatly impact the humidity levels in your home, it can affect what form that humidity takes.

Drawbacks to Increased Condensation

Condensation inside of your home is not exactly desirable, for a number of reasons.

For starters, there’s the discomfort of accidentally touching any wet surfaces.

Additionally, the presence of any water spots, pools, and streaks means more cleaning. Windows are a common location for condensation, and can become dirty or streaky quickly as water forms on their surfaces.

Lastly, the majority of your home isn’t meant to withstand lots of water exposure. Over time, you may experience water stains on walls, ceilings, and furniture depending on where water tends to condense in your home.

Anything wooden in your home may also develop rot—from furniture to hand railings to window panes. Rotting wood is not the only concern, either. Mold is another issue that may pop up with long-term moisture exposure.

Mold can be extremely hard to get rid of once it’s taken root, as it can “dig into” porous areas and regrow if not completely eradicated.

Not only is mold difficult to get rid of, but it can be hazardous to your health. Living in a space with mold can cause symptoms like difficulty breathing, headaches, fatigue, itchiness, wheezing, or a runny nose. 

Insulation and Winter Humidity

In most places, the coming of winter brings cold and dry air. However, if you live in a well-insulated home, you may still experience high humidity indoors.

This is because many of the daily tasks we perform add moisture to the air. Boiling water, taking a shower, and even washing your hands can all contribute to the humidity in your home.

Boiling water, taking a shower, and even washing your hands can all contribute to the humidity in your home

Sitting water sources like watered plants, beverages, toilets, and pet bowls can all also increase moisture levels.

Since insulation can prevent moisture from entering or escaping the home, you could actually have a humid indoor winter. And since the air is too cold to hold high levels of moisture, you could even experience condensation!

In the winter, condensation that forms on thin and cold surfaces like windows can even freeze into a thin layer of ice.

On the other hand, in winter, we are typically adding heat into the air. This will increase evaporation of water from all the previously discussed sources. As the air is warm, this water will remain in the air as water vapor, making it feel more humid.

Get a Dehumidifier

If you install insulation and humidity becomes an issue, you’ll need to actively reduce the amount of moisture in the air.

It’s often best to attack the problem at the source. In this case, that would mean getting a dehumidifier to literally remove moisture from the air in your home.

Depending on factors like how large your home is, how severe the issue is, how powerful the dehumidifier is, and where moisture seems to hang the most, placing a second humidifier to place in another area of the home can also be helpful.

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Insulate Anyway

Although insulation can potentially cause issues with how you experience humidity, I would still suggest insulating. 

Benefits to a properly insulated home

Properly ventilating the home and/or using a (de)humidifier as needed can also solve potential humidity issues, and there are a number of benefits to a properly insulated home.

  • Significantly lowered energy costs on heating/cooling
  • A reduced carbon footprint
  • Increased home value
  • A quieter home (insulation affects sound, not just temperature!)
  • More comfortable temperatures year-round
  • Better health (more consistent and tolerable temperatures reduce strain on the body. Cold temps can suppress the immune system!)

Insulation R-value: What Does It Mean?

Sources

https://aroundclock.com/blog/high-indoor-humidity-problems-in-winter/

https://dampsolving.com/insulation-cause-condensation/

https://howthingsfly.si.edu/ask-an-explainer/how-it-warm-air-able-hold-more-water-vapour-cold-air

https://osb.westfraser.com/blog/can-i-compress-insulation/

https://usainsulation.net/why-re-insulate/insulation-benefits/

https://www.attainablehome.com/does-insulation-control-moisture-humidity/

https://www.endsleigh.co.uk/blog/post/what-causes-condensation-7-tips-prevent-it/

https://www.envirovent.com/blog/14-ways-to-help-reduce-condensation-in-your-property/

https://www.greenbuildingadvisor.com/article/is-compressed-fiberglass-insulation-really-a-problem

https://www.paragon-protection.com/the-top-benefits-of-insulating-your-home/

https://www.reenergizeco.com/blog/8-benefits-home-insulation/

https://www.rockethomes.com/blog/homeowner-tips/mold-removal

https://www.scientificamerican.com/article/stay-warm-with-thermal-insulation/

https://www.washingtonpost.com/news/capital-weather-gang/wp/2013/09/11/does-warm-air-hold-more-water-vapor-than-cold-air/

https://www.wisepropertycare.com/news/condensation/insulation-can-cause-condensation/

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