House thermal insulation with mineral wool

Should You Add Insulation During a Roof Replacement?

When considering a reroofing project, roofing insulation should be at the top of your list!  Why?  The roof will be opened, and it is the perfect time to make the structure more weather-tight and reduce utility bills.  Insulation is a benefit, regardless of whether you’re looking to re-roof your commercial or residential building.

Since insulation makes your space more energy efficient, it’ll also save you money on your energy bill!  At SUNVEK, we see firsthand how insulation saves energy by keeping cool air in during the summer and warm air during the winter.  We’re here to assist you when considering the best roofing insulation options for Phoenix and the surrounding areas.

First Off, How Much Insulation Do I Need in Phoenix?

Too much insulation has diminishing returns, so you want to find the right balance.  At a certain point, insulation stops being effective.  You want to use the proper insulation for your climate to protect your building without wasting precious resources.

United States building codes are based on seven unique climate zones, with Phoenix  (and the surrounding areas) located in Climate Zone 2.  For Climate Zone 2, the recommended R-value is 38.  But don’t worry about this too much—our roofing experts can take a look at your commercial space and make recommendations based on its size, age, structural integrity, and existing insulation.

Let’s Take a Closer Look at R-Value

One way we measure insulation’s effectiveness is by calculating its R-value.  R-value measures how well insulation resists heat.  The higher the value, the more insulation the material provides.  Keep in mind the moment typical roofing insulation gets wet, its R-value decreases significantly, so we want to eliminate the possibility of that happening!

Related Reading: The Basics of R-value 

With that in mind, let’s take a closer look at a few different types of insulation that you can choose.  Our recommendations include polyisocyanurate and polystyrene — a versatile plastic mixed with air to create foam insulation.  Due to its high R-value, durability, and water resistance, it is the best insulation for hot climates.


Expanded polystyrene (or EPS for short) is made from polystyrene infused with a foaming agent.   Since the 1950s, EPS has been a top choice for home- and business owners because of its flexibility and low cost.  It expands when exposed to heat to form an insulating material and is commonly formed into panel stock of varying thicknesses.

Expanded polystyrene is the most cost-effective of the bunch. EPS also has an average R-value between R-3.6 to R-4.2 per inch, depending on the panel’s density.

Fun fact: EPS is also used to manufacture styrofoam coffee cups.


Polyisocyanurate (or ISO)  is a closed-cell foam and the ideal choice for a low-slope building.  On the higher end of the cost spectrum, ISO is commonly produced in thicknesses of up to 2.6” 1” panels.

Polyisocyanurate has the highest R-value of the three, starting at R-8 per inch, although that typically decreases to R5.5 per inch over time.


When you think of insulation, extruded polystyrene (or XPS)  is probably what comes to mind—it’s known for its blue, green, or pink color.

XPS is made of polystyrene crystals blended and melted together with special additives.  It’s processed through a die and expanded into foam!

XPS sits right in the middle of EPS and ISO in terms of both price and performance. It also can be produced in panels of varying thickness. And its R-value is R-5 per inch, right in the middle of its counterparts.

Call Arizona Roofing Experts You Can Trust

Foam products provide superior insulating capabilities for your commercial roofing insulation needs.  If you’re looking for the best insulation for hot climates, reach out to our team for assistance.

Are you ready to move forward with re-roofing your home or insulating your building?  Do you still have lingering questions?  Either way, we welcome you to contact us to get your space ready for any and all Arizona weather headed our way!  Whether you’re dealing with a leaking roof or concerns about how your commercial roof reflects your business, we can get your space protected and looking great.

Our roofing experts proudly service the following areas: ​​

I have used this company for years with many of my projects, for services, like roof inspection, roof repairs and installation and found them to be very professional, reliable, and quick in their services and responses. Highly recommend them for any roofing job. ANDY ANG

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