R&A University

Updates, news, and information to educate and empower owners.

What is C-Value in roofing insulation?

18 Apr 2016 | Under Energy Efficiency, Roofing | Posted by | 0 Comments
R&A Contracting - Energy Value ratings commercial roofing

This post is part of four-part series exploring energy efficiency values in insulation, such as K-Value, C-Value, R-Value, and U-Value.

What’s C-Value? Is C-Value the same as K-Value, R-Value, or U-Value?

We know that insulation is designed to inhibit environment influence due to weather and other external forces, but how do we know which insulation type is better or worse than the next? Insulation types are rated against a variety of energy efficiency values, such as K-Value, R-Value, C-Value, and U-Value. Today we’re exploring the C-Value energy efficiency rating and how it relates to the quality of a particular insulation type.

What’s C-Value?

The “C” in C-Value stands for “Conductance”. This is a specific instance in which the density of an insulation material dictates its C-Value. ASTM International defines C-Value as the following:

“Conductance, thermal, n: the time rate of steady state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces.” (ASTM International C168)

The definition of C-Value is very similar to K-Value with one important distinction: the thickness of the material in question. Let’s remove the confusing part of C-Value by simply stating that the thicker the insulation, the lower the C-Value, the more energy efficient the material. Thicker insulation = better insulation.

So, are C-Value and K-Value the same concept?

Not quite. K-Value measures the thermal conductivity across a surface area in response to energy flowing directly into an insulation. (Thermaxx) If you picture a fan blowing cold air directly onto a 2 ft. x 2 ft. piece of insulation, that measures the K-Value. The C-Value determines that the same 2 ft. x 2 ft. area will be have a different environment if the insulation is 1″ thick compared to 6″ thick. Obviously, the thicker insulation will be able to slow down, if not altogether stop, the cold air being blown by the fan.

No matter how high you turn up the fan or how cold you continue to cool the air, it doesn’t change the C-Value because the thickness of the two materials stay the same. If you shrink the 6″-thick insulation down to 4″ thick, you reduce the C-Value by 33% (6″-2″ = 4″ or 67% of 6″).

Again, the math may seem complicated until you see how energy affects different insulation types. Our R&A Contracting team works with commercial roofing clients across the St. Louis area to show you how much an energy value, like C-Value, can change your energy bills in just a few months. If you have questions about choosing the right energy-efficient roofing material for your warehouse or office space, we’re St. Louis’ best at keeping you and your team comfortable, no matter what season it is.

I’d be an idiot if I did not take this opportunity to communicate to you how much we appreciate the way in which you conduct business and take care of our facility. In my experience you, and your team, are at the top of the list of all the roofing companies I’ve dealt with over the years. Thank you!

Jim Lowry - Bissinger's Handcrafted Chocolatier

Eric and crew were really nice to have around. They were courteous, careful and caused little if any disruption. Their work looks good too! To be honest… a good experience with a product that I initially had misgivings about. I’m a convert because of Bubba, Sam and Eric. Thank you.

Jim Lowry - Bissinger's Handcrafted Chocolatier

“I want to thank the crew at R&A for a job well done on our very leaky roof at the shop. It is certainly nice to have the drips and rivers gone from the shop when it is raining. I also wanted you to know how much we appreciated that the guys were able to stay out of our way and allowed us to do business as usual without any problems or interruptions. The roof looks great and the clean-up after the job made it so we couldn’t even tell you’d been here. Thanks for doing what you do so well!”

Jay Moore, President of Safe Way Tire and Auto Center

“My wife and I were on vacation when water pipes burst in our house. We got a hold of Craig and the R&A crew was able to start evacuating the water immediately. The best part was that they were able to start work before we even returned home. It was a very fast turnaround considering the extensive amount of water damage.”

Will from Dardenne Prairie, MO

“Craig and Mike came out in a timely fashion when we needed the work done. They did a reliable and quality job.”

Jerry from SLR Properties

“Craig helped us out tremendously with the insurance process. Timely and very professional.”

Lindell from Greater Missouri Builders (GMB)

“We purchased a house and there was some damage to the roof. Very impressed with the thoroughness of Mike’s inspection. Very comfortable with their explanation of what needed to be fixed. Most impressive was the way they protected our landscaping. Really liked the way they treated me as a valued customer, even though it was only a small project.”

Ross from Troy, MO

“I use R&A Contracting when my commercial roofs receive storm damage. They work on our behalf through every step of the insurance claim process. They perform all of the work and complete the insurance process, making our roofs better than they were before the storm.”

Director of Facilities for a large Property Management Company

“The team at R & A Contracting responded immediately when notified of our water disaster. They removed water-damaged materials and property quickly and restored our home even before the final settlement from our insurance company. They minimized how long our family had to live in a hotel and got us back to normal as fast as possible.”

Will from O'Fallon, MO