Types of Insulation

Types of Insulation

Overview

Knowing what’s the best insulation for your project can be challenging. Below is a clear cut comparison between the common types of insulation contractors use today.

While it may not seem like an important topic, insulation has massive impact on utility bills, safety, and comfort. A couple of minutes now can directly improve your quality of life while at home.

Insulation Types Summary

There are three insulation types, each with their strengths and weaknesses.

Fiberglass has the lowest upfront cost of any insulation. However, it costs more in the long run, is prone to issues, and often makes homes uncomfortable.

Cellulose insulates far better and offers many additional benefits for a slightly higher upfront cost. If the project costs are wrapped into financing, such as for renovation or new home construction, cellulose is less expensive because it reduces monthly heating and cooling utility bills more than it increases monthly financing payments.

Spray foam insulation offers the highest quality insulation and gets the job done when other options can’t, but costs the most.

Insulation Types Comparison

Fiberglass Insulation

Lowest Upfront Cost

Quality Score: 1

Cost: $

R-Value: 3.0-3.3/inch*

Stable R-Value: No

Air Blocking: No

Moisture Resistant: No

Pest Resistant: No

Radiant Barrier: Optional (increases cost)

Fiberglass is made from woven minerals processed at high temperatures and comes as fiberglass batts and blown insulation versions. It traps air between layers, which act as buffers against heat transfer.

Cellulose Insulation

Low Cost, Great Performance

Quality Score: 4

Cost: $$

R-Value: 3.0-3.3/inch*

Stable R-Value: Yes

Air Blocking: Yes

Moisture Resistant: Yes

Pest Resistant: Yes

Radiant Barrier: Yes

Cellulose is made from pulverized fibers, such as from recycled paper, and comes as a blown in product. It traps air in pockets between the frayed fibers, which slow heat transfer.

Spray Foam Insulation

Highest Performance Available

Quality Score: 5

Cost: $$$$$

R-Value: 6.5-7.5/inch*

Stable R-Value: Yes

Air Blocking: Yes

Moisture Resistant: Yes

Pest Resistant: Yes

Radiant Barrier: Yes

Spray foam is a combination of separate oil and polyurethane mixtures that turn to solidified foam when they touch. Spray foam forms with small isolated air bubbles which drastically limit heat movement.

*A Note on R-Values

Before diving too deep into insulation differences, it’s important to understand the common measure of the insulating capacity or how insulative a material is. Construction companies and insulation contractors use R-Value for this measure. It only tells a very small part of the picture. 
  
There are 3 ways heat moves and R value only measures 1 of them–conduction, or heat moving through an object. And R-value for the exact same object or material will have a different R Value as it gets colder or warmer. For example, fiberglass has a highly fluctuating R Value based on its temperature.
 
Air can also move heat, which is called convection. Even if you don’t touch boiling water, holding a hand over it can still get very hot very fast.
 
The third way heat moves is radiant transfer. Often, perfectly sealed windows feel like they are drafty when it’s cold outside. That sensation is actually heat radiating off the body and out the window, regardless of air movement. It’s how the sun heats the earth. 
 
So although R Value is often the only listed measurement of insulation quality, it is misleading.

*R-Value Explained

Important Note on R-Value

In short, thermal resistance value (R-Value) measures a materials’ ability to prevent heat from moving through it. However, this measure is highly deceptive because the R-Value of a material changes with its temperature, and listed R Values are at 70 degrees. Heat also moves in other ways.

Temperature or moisture level can radically change R-Value. Oven mitts have a good R-Value because heat moves through them slowly. If you get the same oven mitt wet, its R value drops and it transfers heat very quickly.
 

Insulation Scores Explained

Fiberglass Insulation

Quality, R-Value, and Air Blocking

Fiberglass Insulation can technically be an effective insulator, but it performs worse the colder or warmer it gets from 70 degrees. Any warmer or colder and the R-Value drops considerably. Unfortunately, this means it works progressively worse the more it’s needed. 

As a perimeter insulation, if the areas around it aren’t air sealed, air will move through the insulating layers within the fiberglass bats and break the insulation functionality. 

Cellulose Insulation

Quality, R-Value, and Air Blocking

Cellulose Insulation does a great job as a thermal insulation in buildings. Its R Value improves as it gets colder or warmer outside, and blocks air movement so outdoor air can’t sneak inside as easily. This also means more comfort from temperature stability throughout the building, and it’s made from recycled materials.

Although it has a similar “listed” R Value as fiberglass, its actual performance usually is much better–up to 40%.

Spray Foam Insulation

Quality, R-Value, and Air Blocking

Spray Foam insulation is the best insulator commonly available. It has all the benefits of cellulose plus complete air sealing (rather than air blocking), requires half the space (depth), and sticks to the target surfaces. This means spray foam insulation gets the job done better and when nothing else can, such as on vaulted roofs, cathedral ceilings, and insulating basement walls in crawl spaces.

Foam insulation only takes a few hours to set. After this and the air cycles, spray foam insulation is as safe as any plastic or styrofoam in a home. 

Fiberglass Insulation

Moisture and Pest Resistance

Fiberglass “breaks” when it becomes wet. Even after drying, damage to the insulation remains. Should condensation or a leak occur, the fiberglass performance is permanently degraded and must be replaced to prevent a cycle of increasing damage.

Rodents and pests will tunnel and nest in fiberglass. It does nothing to repel rodents or insects.

Cellulose Insulation

Moisture and Pest Resistance

Cellulose absorbs water from surrounding surfaces into its core and safely dissipates the moisture over time. It does this without becoming damaged or risking mold and mildew growth. This protects the home or building from many potential health hazards and creates a safer and more comfortable environment. 

The same environmentally friendly cellulose treatment that prevents mold and mildew also repels rodents, pests, and suppresses fires. 

Spray Foam Insulation

Moisture and Pest Resistance

Spray Foam resists water as well as a sheet of plastic, prevents humid air from entering the home, and can prevent condensation development when other types of insulation may not. Since it doesn’t absorb water and is unlikely to develop condensation, it rarely develops mold and mildew while completely protecting the surfaces it covers.

Rodents and pests fully avoid spray foam, and many companies and contractors utilize the expanding nature of foam insulation to close off existing access points.

Radiant Heat Blocking

A Key to Comfort
Many people wonder why their house feels so much warmer or colder across seasons despite the thermostat reading the same temperature. The actual air temperature is the same, but it feels colder in winter because of radiant heat loss. Heat literally gets pulled out of the body and through windows and walls to the cold outside, regardless of air movement or R-Value.
 
This is why people who have radiant blocking insulation never go back. With a consistent radiant barrier in place, a home actually feels like the temperature the thermostat reads all the time. It is a noticeable difference.
 

Automatic

State Rebates & Incentives

Many (though not all) Wisconsin insulation projects are eligible for hundreds of dollars in rebates through the state’s Department of Energy. We typically capture at least 1 rebate per week for our clients.

We are certified to implement these rebates and complete nearly all the paperwork for you. We even instantly discount the rebate from your invoice, so you’re not left waiting for the rebate check to arrive.

Know YOUR Numbers

Planning with general numbers often leads to inaccurate estimations and budgets. That’s one of the many reasons we offer free estimates. Whether you need a quick fix or are planning for work next year, work with actual numbers specific to you.