Attic - Walls - Floors - Basement - Crawl Space - Insulation
Aug132012

What is R Value?

Published by Rease at 4:30 PM under Blog

 The term “R value” gets thrown around a lot when discussing construction, building materials, heating and cooling systems, and insulation. Everyone loves to tell you about their R Value, but if you don’t know what it means, what good is that information to you? Allow us to explain.

 

 

Quick definition

 
R value is a measurement of thermal resistance or heat transfer. The higher R value a building has, the more resistant it will be to heat flow. Building materials such as metal or glass have a low R value, while insulation has a much higher value.
 

Why should I be concerned about R Value?

 
As the definition states, the higher R value your home has, the more resistant it is to heat flow. Basically, a higher R value means better temperature regulation in your home and thus lower utility bills. Sadly, many builders only meet the bare minimum, so while they may try to impress you by throwing out arbitrary numbers, it’s important to recognize the difference between “standard procedure” R value and optimal R value.
 

How is R Value calculated?

 
R value is calculated based on the material. For insulation, the calculations are as follows:
 
Cellulose: 3.5 per inch
Fiberglass: 2.8 per inch
Rockwool: 3.2 per inch
Vermicullite: 2.7 per inch.
 
So, if you have 10 inches of fiberglass, you have an R value of 28.
 
Cellulose:
 

 

Fiberglass:                     

                                                                                                     

 

So what’s a good R value?

 
The “bare minimum” R value is R 38. However, based on our experience, we have found that most homes are only working with R 15. Sadly, neither of these values are what would be considered optimal. The optimal value varies by location, but in the St. Louis area, the recommended R value for optimal performance is between R45 and R60.
 
Chances are your home was built with the bare minimum and has since deteriorated down to R15 or lower. By bringing your R value up to optimal performance standards, you will be enhancing your home’s ability to regulate temperature, which means much lower utility bills and a more comfortable home.
 
Still not sure? Take a look at our online quote calculator and get a quote within 5 minutes. No obligation, just information!