Does insulation make it cooler in summer?

Author: Lula Mosciski  |  Last update: Sunday, July 27, 2025

A properly insulated attic can benefit your home in many ways, beside just keeping the home at a comfortable temperature year round. The short answer, yes, insulating the attic is an effective way to keep your home cooler during the summer months.

Will insulation keep a house cool in summer?

Insulation can even help keep your home cool, because most types - certainly external wall and likely also cavity wall - will stop your home from getting as hot in the first place.

Does insulation keep hot air out?

The short answer is yes. Effective insulation can help keep cool, air-conditioned air inside and keep the heat out for a more comfortable summer at home.

How much cooler does insulation make a house?

How many degrees of difference insulation makes on its own depends on the type of home you have, what the weather is like and what kind of insulation you have. Depending on what you choose, you could see a five- to 20-degree temperature difference just based on the insulation alone.

Does insulation help with air conditioning?

In addition to reducing air conditioning costs, effective insulation also has numerous other benefits. It helps regulate the temperature in your home, making it more comfortable year-round. Insulation can also reduce noise levels, improve indoor air quality, and increase the overall value of your home.

LEARN: See how insulation can help keep you cool in the hot summer months

Does extra insulation let AC run cooler?

Reduces Heat Transfer: Adequate insulation acts as a barrier, preventing heat from your hot attic from radiating down into your living areas. This significantly reduces the workload on your AC, allowing it to maintain a comfortable temperature without constantly battling the heat.

What happens if your house is not insulated?

The lack of insulation in homes can lead to condensation and mould growth, creating unhealthy living environments and potentially causing structural damage. Insulation slows the movement of heat through the walls, roof, and floors, maintaining a more consistent indoor temperature.

Can you put too much insulation in a house?

It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers. That's when mold starts to grow.

Are 90% of homes under insulated?

Based on new research, the North American Insulation Manufacturers Association (NAIMA) estimates that roughly 90% of existing U.S. homes are under-insulated. That means that the occupants are less comfortable, and both energy and money are being wasted.

What happens if your house is too hot?

“Pipes can expand in high temperatures, leading to leaks or even bursts, especially in older systems. And when it comes to electricity, the increased power consumption during hot spells can overload your system, potentially causing circuit issues or, in worst-case scenarios, electrical fires.”

Can insulation keep things cool?

Insulation in your home provides resistance to heat flow and lowers your heating and cooling costs. Properly insulating your home not only reduces heating and cooling costs, but also improves comfort.

Is adding insulation to an attic worth it?

Should you insulate your attic roof? Insulation is a wise choice to increase the energy efficiency of your home. Quality insulation will make it more cost-effective to heat and cool your home, The Department of Energy's estimates range from a 10% to 50% savings, depending on several factors.

Why is my attic cold in the summer?

The exfiltration of warm interior air through your attic and the infiltration of cold outside air through your basement or crawl space could be to blame. Due to your attic's location at the top of your house, it can be a major location for energy loss, especially if you lack sufficient insulation.

How to make a house cooler during summer?

If the summer temperatures have you needing to chill out, try our tips.
  1. Open your windows at night. ...
  2. Close your window coverings. ...
  3. Insulate and air seal your home. ...
  4. Bake and wash at night. ...
  5. Fire up the grill! ...
  6. Install an exterior window shade. ...
  7. Use your fans in the right places. ...
  8. Use your exhaust fans.

What does insulation do in the summer?

The summer benefits of insulation are similar to the benefits it offers your family in the fall and winter. Just as insulation prevents chilly air from penetrating your cozy home in the winter, it also keeps outdoor heat from entering it in the summer.

Does extra insulation really help?

Unless your home was specially constructed for energy efficiency, you can probably reduce your energy bills by adding more insulation. Many older homes have less insulation than homes built today, but even adding insulation to a newer home can pay for itself within a few years.

How do I know if my house is poorly insulated?

When floors, ceilings and walls are cold to touch, it's a sure-fire sign that your home is under-insulated. All these parts of your home should feel dry and warm. Conversely, your external walls should be cold, as great insulation keeps the warmth within your home.

How much heat is lost through insulated walls?

About 35% of the heat will escape through the walls and through gaps, in and around windows and doors, and about 10% of heat will disappear through the floor. Taking action to make sure your home is energy efficient has many benefits. For your pocket, for your comfort and for the environment.

Are mobile homes insulated underneath?

Mobile homes have little to no insulation in their walls, ceilings, and underbelly. They also have the reputation for begin drafty and have unstable interior temperatures, leaving you and your family uncomfortable.

Can your R-value be too high?

The optimal R-value for most homes is 30, but you can go as high as 38 if you live in a tropical climate. Anything higher than 38 indicates an over-insulated space. While you might think that too much insulation can't be bad, there are some significant consequences to consider.

Is it okay to double up insulation?

As a general guideline, it's advisable to install double layers of thermal insulation throughout your house. Nevertheless, this may not be feasible in all areas due to space limitations. Typically, it's not practical to add two layers of insulation within the walls of your home.

Can too much insulation cause mold?

Many of us know what causes mould; when moisture is trapped in the rooms of you home. Sometimes, there is insufficient insulation in the walls, so mould grows. However, not many people realise that additional insulation isn't always the answer. In fact, too much insulation can be the secret cause of mould.

Why is my house colder after insulation?

Even with new insulation, your home might feel cold due to air leaks and drafts around windows, doors, and vents. A reason can be gaps or compression in insulation can limit its effectiveness, diminishing thermal resistance.

Do cold walls mean poor insulation?

What causes cold walls? Poor insulation is the main reason why walls feel cold, especially in older properties with solid walls. Roughly 35% of heat loss is through walls and gaps, in and around windows and doors. Walls transfer heat and the warmth from your home will escape outside if your walls are poorly insulated.

How do you keep a poorly insulated house cool?

How to Keep Your House Cool Without A/C
  1. Invest in the Right Ceiling Fans. ...
  2. Optimize the Fans You Have. ...
  3. Flush Out Hot Air in the Evening. ...
  4. Update Your Insulation. ...
  5. Weatherize Your Windows and Doors. ...
  6. Switch to No-Heat Lightbulbs. ...
  7. Install a Whole-House Fan. ...
  8. Create a Crosswind With Multiple Fans.

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