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Insulating an existing home

Can You Spray Foam Insulation in an Existing Home?

Proper insulation makes sure that the ideal temperature inside a house remains ideal despite extreme weather conditions. It is one way to make a home as comfortable as it should be. In this article, we will walk you through how to insulate an existing home.

Temperature is not easy to deal with, especially with ever-changing seasons that can sometimes come with unpredictable changes in temperature.

Insulating an existing home can help you manage these temperature changes so that the situation will not get into your nerves and affect your mood.

Steps on How to Insulate an Existing Home

Proper insulation does not only help you manage the temperature of your home structure but your energy consumption as well.

A poorly insulated home can greatly impact energy costs. Hence, homeowners are taking the necessary steps to properly insulate their homes.

So, how do you insulate a house that has already been built? Here’s how you can save 10% of your energy bill through proper insulation:

1. Check How Much Insulation Your Home Needs

Insulate your house

There are resources that can provide you with the estimated insulation needs for your home.

The California Energy Commission Consumer Energy center of the North American Insulation Manufacturers Association, for example, can help you determine how much insulation is recommended for your existing home.

According to SFGate, “most of America, from California and across the South and Midwest to New Jersey, requires R38 to R60 in attics and R13 to R15 in wall cavities”.

2. Insulating Your Attic

If you want to keep your drywall intact, add insulation under the roof of your attic. This is one place in your home where insulation is most needed because you will get the most benefit. You can insulate your attic in several ways, such as:

Loose-Fill Insulation

Consider these steps when insulating your attic:

  • Add loose-fill insulation in the form of cellulose, rock wool, or fiberglass beads.
  • Add any loose-fill on top of the existing loose-fill insulation.
  • Make sure your insulation is 8 to 12 inches to meet the minimum requirements.

Batt or Roll Insulation

This is another easy way to insulate your attic using fiberglass, cotton, or wool materials that have about the same R-value. Two ways that you can install these materials in batts or rolls are:

  • Between ceiling joists or over them
  • On top of any existing loose-fill insulation

Spray Foam Insulation

Spray foam insulation

A more advanced method of installing insulation is using spray foam. With this method, you do not need to remove your drywall.

Spray foam is a popular type of insulation that is made up of poly material. It is applied by spraying.

When it is sprayed as a liquid, it expands when it gets in contact with air. This feature allows it to fill crevices, making it a very effective insulating material.

When applied carefully and properly, it will leave no openings where hot air can escape or where cold air can penetrate.

Can you spray foam insulation on an existing home? Definitely, yes.

When you insulate your attic, you can spray foam between roof rafters to fill cavities. If there is excess material on the surface, you can easily trim it off using a knife or saw.

3. Insulating Your Walls

It is also possible to insulate your walls without needing to remove drywall by following these steps:

  • Cut holes in the exterior siding
  • Blow loose-fill cellulose or spray foam into wells from the outside
  • Cut a hole 1 ½ to 2 inches in diameter between each pair of studs at the top of the wall
  • Spray cellulose or foam into the cavity
  • Replace the hole cut-outs by filling holes with wood filler
  • Sand smooth the surface
  • Paint to restore the siding

4. External Wall Insulation

How is internal insulation different from external insulation? The very first step when you want to install external wall insulation for your home is proper inspection.

Hire professional contractors to inspect the outside walls of your home to identify problems that might occur during installation.

They will most likely do a power wash to remove accumulated dirt on your wall and other debris like paint chipping off. This process will make it easier for them to check on areas that need repairs before installing your insulation material.

The insulation installation process will go on with the following procedures:

  • Repairing visible cracks on the walls of your home
  • Removing loose debris
  • Use high-quality filler to repair damage and make a uniform surface on the external wall of your home
  • Renders are repaired and damaged renders are removed to match the existing surface
  • Bagging may be performed where surfaces with poor quality or are unpainted will get stabilization
  • Masking areas that are not subject to spraying with heavy-duty paper and masking tape. These areas that will not be sprayed include the doors, drainpipes, gutters, windows, and other similar structures.
  • Applying the insulation. Rigid foam panels are the top choice for reroofing or adding siding to external walls. These panels are nailed on the roof or wall sheathing and shingles.

5. Insulating Your Floor

If you have an uninsulated concrete subfloor, it can absorb 30% of your home’s heating. Other types of floors, like wooden, carpeted, and vinyl floors, are more flexible because you can install insulation underneath when you renew them.

Flooring insulation is typically installed under your subfloor between floor joists. It is similar to the insulation process of walls. The U.S. Department of Energy recommends R-11 (3 ½”) insulation under floors in warm climates and an R-25 (6” to 8”) in cold climates.

Why You Should Insulate Your Existing Home

No matter what type of insulation material you use, make sure that it gives you the desired outcome.

An expert insulation contractor such as EcoStar Foam will be able to inspect your home and discuss with you the best option considering your budget and the needs of your home.

Now that you know how to insulate an existing home properly, you can better keep the desired temperature in your house all year round, protecting it against cold during winter and excess heat during summer.

More From EcoStar Foam



Star Spray Foam Insulation is proud to provide affordable, efficient insulation services to the community of New Orleans. We have built a reputation in the NOLA area for efficient, high-quality insulation at an affordable cost.

We use quality materials to maximize the amount of heat retained inside your home – and we install them for you hassle-free. Contact us now!