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Best Attic Insulation for California Homes

Blow-in Fiberglass insulation in an attic

With much of California experiencing moderate temperatures during fall and winter, many homeowners don’t have to touch their thermostats to keep their homes comfortable. But did you know attic insulation plays a big role in maintaining that comfort? Insulated attics keep your home cool in the summer and warm in the winter.

To make sure your California home stays at a consistent and comfortable temperature, it’s best to understand the importance of attic insulation. In this blog, the experts at OJ Insulation discuss the different insulation types and which ones are best for your attic.

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How Attic Insulation Keeps Your House Cool in the Summer

Effective attic insulation blocks hot air from coming indoors in the summer and from escaping your home in the winter, which means less strain on your home’s HVAC systems. With insufficient attic insulation, conditioned air could escape, resulting in your AC having to work harder to maintain your desired indoor temperature.

Beyond temperature control, insulation is used to seal air leaks in the cracks and crevices of your attic, making your home more energy-efficient and preventing the formation of dangerous ice dams in the winter — keeping your home safe and comfortable.

Insulation Requirements in California

R-value (resistance value) is a rating system used for measuring how effective insulation is and how much you need, and it varies based on material and location. Your attic is a big factor in indoor comfort and impacts your energy bills.

Your insulated attic must have the correct R-value to keep all of this in check. Each part of the country has its own climate, which means not all R-values are the same.

Insulation R-value map of the U.S. with color-coded regions.

In most of California, the recommended R-value for attics is between R-30 and R-60. A professional insulation installer may assess your current insulation to determine its current R-value and what steps to take to bring it up to standards.

Recommended Types of Attic Insulation

You have a few options when it comes to attic insulation:

  • Fiberglass: One of the most widely installed types of insulation and most recommended for California’s climate, fiberglass consists of extremely fine glass fibers, is available as loose-fill  (blown-in) or rolls and batts, and it’s fairly inexpensive. It’s easy to work with and fire-resistant.
  • Spray foam: Spray foam is created by mixing two materials to create a foam-like substance that expands to create an airtight seal and moisture barrier. Unlike fiberglass, which shrivels over time, spray foam is quick-drying and highly successful after settling for the short and long term.
  • Cellulose: Made from fibers taken from paper, wood and other recycled materials, cellulose is considered one of the most eco-friendly insulation products on the market. It’s useful for blowing into attic cavities and conforms to existing spaces with a long life span.

In addition to these traditional insulation materials, there’s reflective attic insulation, also known as radiant barriers. Radiant barriers are installed in attics to reflect heat rather than absorb it, which reduces cooling costs in the summer.

Trust OJ Insulation for Professional Attic Insulation Services

OJ Insulation is proud to offer top-notch attic insulation services that fit your needs. For over 30 years, we’ve served the California area, maximizing energy efficiency and saving our customers money.

Our professionals can help you decide which insulation is best for your home or commercial project and provide seamless, stress-free installation that’s up to code and long-lasting.

Call (800) 707-9278 to schedule an insulation installation with OJ Insulation today.

Where should you insulate in your home? Check out our interactive infographic:

Home Insulation

We insulate attics, walls and crawl spaces.

Commercial Insulation

We insulate warehouses, offices, studio spaces & more.

Insulation Removal

Do you need to remove old insulation? We can help.


We work with builders to install fireplaces.

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