The Recommended California Attic Insulation R-Value—and Why It Matters

“Hold your horses, I don’t know algebra!” That was the response I got last week while talking to a homeowner about insulation and R-value. I had a good chuckle about that later, but truth be told that wasn’t the first time someone has had that reaction.

Over the years, I’ve come to realize that a lot of folks don’t have a clue what R-value is. To be fair, before I got into this line of work I didn’t either. It sounds kind of intimidating and complex—but it’s really quite simple.

Now, whenever I’m out and about on calls talking with homeowners, I always make sure I take the time to explain not only what R-value is, but why it is so important to consider when insulating your attic. So, without further adieu, I’m going to fill you in on all you need to know about the best California attic insulation R-value for your Sacramento area home.

What Is an Attic Insulation’s R-Value?

R-value is a rating system used for insulation that measures its degree of insulating power. Insulation typically works by preventing conductive heat flow, and R-value measures how effective it is at this. The R actually stands for resistance, of heat flow that is. Insulation with a high R-value means it is exceptionally good at stopping heat in its tracks, while those with a lower R-value will not be as efficient.

Generally speaking, there are four factors that affect the designated R-value of any insulation:

• Density
• Thickness
• Type (such as cellulose, batted-fiberglass, blown-in fiberglass, or foam)
• Installation (i.e., how and where it is installed)

Why Installing Attic Insulation Properly Matters for R-value

It’s fairly easy to imagine that the denser and thicker the insulation, the better it would be at preventing the transfer of heat. And, of course, the type of insulation, whether it’s loose fill cellulose or sprayed foam polyurethane, will affect the R-value as well. But when it comes to how and where insulation is installed, the effect on R-value becomes less obvious—so let me explain.

…if it is compressed in the installation process, a common occurrence with DIY attic installations, it’s R-value will decrease.

How insulation is installed matters because if it is compressed in the installation process, a common occurrence with DIY attic installations, it’s R-value will decrease. This is also the case if two layers of insulation are squashed together in hopes of doubling an R-value. Sorry folks, this actually has the opposite effect.

Where insulation is installed also affects the R-value. Your average attic ceiling is adorned with many joints and studs, right? Since heat travels through these spots much easier, the R-value of the insulation isn’t as high in these areas. That is why it’s important to choose the right insulation and R-value for the attic in your home—and for our Mediterranean climate.

What Is California’s Recommended Attic Insulation R-Value

As you can imagine, the R-value for insulating an attic in Alaska isn’t necessarily going to be the same for insulating an attic in California. In fact, there are building codes that require a certain R-value for insulation depending on where in the country you live. That’s where this nifty EnergyStar chart comes in handy.

Sacramento and most of California are in Zone 3, which requires attic insulation with an R-value between 30 and 60.

On this chart, each part of the country is divided into different zones and each zone has a recommended R-value. We can see that Sacramento and most of California are in Zone 3, which requires attic insulation with an R-value between 30 and 60.

Why Attic Insulation R-Value Matters for California Homeowners

At this point, you may be wondering why this R-value matters so much, especially when it’s for an attic that you probably go into once a year to fetch your Christmas decorations. Well, your attic has a dramatic impact on the temperature throughout the rest of your home as well. Without proper insulation, your attic will heat up in the blazing California summers, warming your home like a furnace. Then, when winter comes along, you could lose up to 25% of your home’s heat from your attic alone.

…when winter comes along, you could lose up to 25% of your home’s heat from your attic alone.

Having a properly insulated attic with the correct R-value helps keep the temperature in your home consistent, which in turn has a positive effect on your HVAC machine. The less conditioned air your home loses, regardless of the season, the easier it will be for your HVAC system to keep your home within a comfortable temperature range. And, if your HVAC is working as efficiently as possible, your energy bill will decrease; an insulated attic equates to an overall energy efficient home.

So now that you know the R-value range recommended for your California home’s attic insulation, and understand how important it is to properly insulate the tippy top of your house, you are probably wondering what the next step may be.  How do you know the exact R-value to choose for your attic insulation? What kind of insulation should you have installed? That’s where a local insulation expert comes in.

Since every home is different, it’s a good idea to have a professional installer come out and have a look at your attic. If you have existing insulation, they can even determine its current R-value and what steps should be taken to bring it up to code. With a pro in charge, you can feel confident that the right insulation will be installed, and installed correctly, so that you can reap the energy saving benefits and keep all that heat in your home this winter—and out next summer.

At Bell Brothers, we believe in the whole home approach to energy efficiency and health. Our trained insulation professionals would not only be happy to insulate your attic, we’d love to make sure your furnace and windows are also working efficiently to keep your house toasty warm throughout the coming fall and winter. Contact us today to schedule a free consultation with one of our local experts.

Wondering how to finance a new furnace, or maybe even new windows and plumbing? HERO is a unique financing option that helps California homeowners afford energy efficient upgrades to their home. Contact Bell Brothers, a HERO-approved contractor, to learn more. Our local HVAC, plumbing, and window specialists will walk you through the entire process, from applications to installation.

Image courtesy Unsplash user David Hellmann