A man installing spray foam on an angled ceiling

Insulation keeps your home warm and can save you money. In the construction industry, how well a particular type of insulation resists heat flow is represented by a value called “R.” 

Among insulation types, rigid foam panels have the highest R-value per inch.  The R-value of each insulation type varies by make and brand, and insulation with higher R-values keeps in more heat than insulation with a lower R-value. 

This article will collate the many different types of insulation by type and R-value, explain what an R-value is, and answer the question, “Can bad insulation make you sick?”

We also included some links to products, which are affiliate links. While we’re not tied to any one product or another, we do make a small commission to support the blog if you would like to purchase using the links.

What Is the R-Value?

The “R-value” is a dimensionless value derived to describe how well a particular material resists the flow of heat through itself. In the minority of countries still using the Imperial system of measurements, the R-value is understood to be given per inch.

The formula for the R-value is as follows:

An image showing the r value insulation formula in grey, blue, and yellow accent colors.


  • ΔT is the difference in temperature measured between the two sides of the material sample, measured in degrees Fahrenheit (℉)
  • A is the area of the material measured in square feet (ft2)
  • t is the time measured in hours
  • q is the heat loss measured in British Thermal Units (BTU)

The units for the R-value are:


Types of Insulation

There are four primary types of insulation that might be used in the construction of a residential building, each with different installation methods and different applications.

The four types are rigid foam or panel, foamed in place, blanket (batts and rolls), and loose-fill.

This article also provides a fifth table with the R-Values of common structural materials for comparison.

Rigid Foam or Panel Insulation

The type of home insulation with the highest R-value, with a few exceptions, is rigid foam or panel insulation. It is also called “foam board” or “continuous” insulation. 

Most varieties of this type of insulation consist of expanded foam sandwiched between two rigid panels.

The foam is usually expanded using a chemical propellant, most often pentane (C5H12) or some variety of chlorofluorocarbon/hydrochlorofluorocarbons (CFC/HCFC). 

CFC/HCFC propellants have well-documented adverse effects on the environment. They have largely been banned or phased out around the world.

A worker in white clothes placing a piece of foam board insulation on the exterior wall of a home for energy efficiency.
Worker placing styrofoam/foam board sheet insulation to the wall. This type of insulation can be used on the exteriors as well as in the interiors of the home.

Rigid foam or panel insulation is usually installed during the construction of residential buildings, including in basements, ceilings, floors, foundations, and walls. It is typically used in interior applications but can be used in exterior applications if the panel materials provide waterproofing and UV shielding. 

In addition, rigid foam offers high insulation value with minimal additional thickness. It can also block electrical short circuits as most materials are non-conductive.

Rigid Foam Or Panel Insulation
MaterialR-Value (Imperial Units)(ft2∙℉∙h/BTU)
Vacuum Insulated Panel14-66
Polyurethane Rigid Panel  (CFC/HCFC Expanded) (Initial)7-8
Polyurethane Rigid Panel (CFC/HCFC Expanded) (5-10 Years)6.25
Polyurethane Rigid Panel (Pentane Expanded) (Initial)6.8
Polyurethane Rigid Panel (Pentane Expanded) (5-10 years)5.5
Foil-Faced polyisocyanurate rigid panel (pentane expanded) (Initial)6.8
Foil-Faced polyisocyanurate rigid panel (pentane expanded) (5–10 years)5.5
Foil-Faced Polyisocyanurate Rigid Panel (Initial)6.8
Foil-Faced Polyisocyanurate Rigid Panel (5-10 years)5.5
Urea-Formaldehyde Panels4-4.6
Molded Expanded Polystyrene Foam (EPS) High Density4.2
Phenolic Rigid Panel4-5
Molded Expanded Polystyrene Foam (EPS) Low Density3.85
Fiberglass Rigid Panel2.5
Wood Panels2.5

Where Do You Buy Rigid Foam Board Insulation?

Here are some common in-stock (usually) foam boards that you can pick up for yourself. You can pick the thickness based on your specific application and where it’s being installed, and the R-value will differ slightly also.

ProductDetailsRough Cost
1-inch thick R-53/4 inch thick R-5$17
FOAMULAR 150 1 in. x 4 ft. x 8 ft. R-5 Scored Square Edge Rigid Foam Board Insulation Sheathing2-inch thick R-7.7$25
R-Tech 2 in. x 4 ft. x 8 ft. R-7.7 Rigid Foam Insulation2 inch thick R-7.7$24
FOAMULAR 1/2 in. x 4 ft. x 8 ft. R-3 Square Edge Rigid Foam Board Insulation Sheathing1/2 inch thick R-3$19
R-Tech 1 in. x 4 ft. x 8 ft. R-3.85 Insulating Sheathing1 inch thick R-3.85$14


Also called “spray foam,” foamed in place is the newest type of insulation used in residences. It is also the best insulation type for inserting additional insulation into existing buildings. 

Foamed-in-place insulation can also be installed inside existing cavities enclosed by walls, unfinished attics, and inside new walls before installing drywall or sheetrock. Before it hardens, it is essentially a liquid and can fill cavities of any shape.

Furthermore, foamed-in-place insulation is an expanding foam product applied from containers containing its base compound under pressure. When removed from the container, it expands to many times its original volume.

A man spray foaming the ceiling of an attic roof.
It’s advised to wear the right gear before installing foamed-in-place insulation.

Like other expanding foam products, foamed-in-place insulation can stain clothes and irritate skin and is not generally fit for DIY use. Protective clothing consisting of coveralls, safety glasses, and a facemask should be worn when working with it.

Foamed In Place
MaterialR-Value (Imperial Units)(ft2∙℉∙h/BTU)
Polyisocyanate Spray Foam4.3-8.3
Closed-Cell Polyurethane Spray Foam5.5-6.5
Urea Foam5.25
Phenolic Spray Foam4.8-7
Urea-Formaldehyde Foam4-4.6
Home Foam3.9
Open-Celled Polyurethane Spray Foam3.6
Icynene Spray3.6
Cellulose Wet Spray3-3.8
Polyethylene Foam3
Cementitious Foam2-3.9

Where Do You Buy Spray Foam?

For the DIYers, there are a few good options for you, depending on the size of your project. For small areas, going with a regular, affordable spray can do the trick.

For slightly larger projects, try the Great Stuff Pro Gaps and Cracks kit, which includes qty 12 cans that are 24oz, (not the smaller 16oz), and includes the applicator gun as well.

Where Do You Find Spray Foam Insulation Contractors?

You should be able to search for spray foam insulation companies online on Google and Google Maps as we all do for most things. These searches should help you find a suitable insulation contractor to help with the installation process.

Another option (and my personal first go-to) is Thumbtack (this is an affiliate link that helps support the blog content if you use it). You can search specifically for insulation installation, and I usually have a number of companies that will respond with quotes and guidance.

Thumbtack's homepage, showing the search box for insulation contractors, and a women with a camera pointed at us smiling for their main image
Get matched with the right professionals according to your budget and needs, thanks to Thumbtack!

Blanket: Batts and Rolls

Blanket insulation, often sold in units called “fiberglass batts” or “rolls,” is the type of insulation most often installed in unfinished walls, floors, and ceilings. Blanket insulation is generally sold in precise widths corresponding to the most common stud lengths in the country, typically four or six feet. 

Due to the degree of standardization in the construction industry, blanket insulation is typically the easiest to install. Installing it is often within the ability of a typical DIY home improver. 

Blanket insulation is also inexpensive and requires little labor or specialized equipment to install.

Blanket: Batts and Rolls
MaterialR-Value (Imperial Units)(ft2∙℉∙h/BTU)
High-density Fiberglass Batts3.6-5
Fiberglass Batts3.1-4.1
Cotton Batts (Blue Jeans Insulation)3.7
Sheep’s Wool Batts3.7
Rock and Slag Wool (Mineral Wool Insulation) Batts3-3.85

Loose Fill

Loose-fill insulation consists of a large amount of loosely bound or free particulates. While it can be sold in large bags, it is commonly blown in using air hoses.

Oftentimes, you may install loose-fill insulation in existing or new cavities enclosed by walls and unfinished attic floors. It can be used in new construction and retrofitting existing buildings.

Loose Fill
MaterialR-Value (Imperial Units)(ft2∙℉∙h/BTU)
Icynene Loose/Pour Fill4
Cellulose Loose-Fill3-3.8
Rice Hulls3
Rock and Slag Wool (Mineral Wool) Loose-Fill2.5-3.7
Fiberglass Loose-Fill2.5-3.7
Perlite Loose-Fill2.7
Vermiculite Loose-Fill2.13-2.4
Thinsulate Clothing Insulation1.6-2.9
Straw Bale1.45
Loose-Filled Wood Products (Woodchips, etc)1
Snow (Dihydrogen monoxide)1
cross-section of a wall with 2x4 studs packed with crumbly gray cellulose insulation in between
Blown-in cellulose insulation foams are an excellent insulating blanket when you spray it in.

Structural Materials

In general, structural materials like brick and wood are not intended to serve as primary insulation for residences, but they do provide some insulation.

Structure Materials
MaterialR-Value (Imperial Units)(ft2∙℉∙h/BTU)
Most Softwood1.41
Aerate/Cellular Concrete1
Most Hardwood0.71
Poured Concrete0.08

Can Bad Insulation Make You Sick?

Old or improperly installed insulation is a common contributor to poor indoor air quality. There are four primary ways bad insulation can make you sick.

  • Respiratory irritation
  • Skin irritation
  • Attracting unwanted pests
  • Cancer risk

Respiratory Irritation

The human respiratory system is vulnerable to exposure to many irritants, which can come from insulation.

There are two primary respiratory hazards presented by insulation: propellant chemicals and loose particulate matter.

The propellant chemicals used in rigid foam and foamed-in-place insulation can be hazardous to human health. They fall under the banner of volatile organic compounds and can be significant contributors to poor indoor air quality and “sick building syndrome.”

Propellants like CFCs/HCFCs and pentane can cause headaches, airway irritation, and inflammation. They can also contribute to chronic illnesses like asthma.

Old or poorly installed insulation will start to break up, releasing particles of itself into the airflow of your house. Some of these particles will eventually find their way into your lungs. This particular matter can consist of either fibers or dust particles, often too small to see. 

According to the EPA, there are several potential adverse effects of inhaling particulate matter. These effects include but are not limited to reduced respiratory function, coughing from fluid buildup and airway irritation, and irregular heartbeat. Chronic inhalation can also cause long-term illnesses such as asthma and silicosis. 

Skin Irritation

It must be a universal childhood experience in industrialized nations to poke your hands behind appliances. You must have also poked into holes in walls and touched something fluffy for your hands to turn bright red shortly thereafter.

Those of us who have done so have first-hand experience of how some types of insulation can severely irritate human skin.

The most common culprit for this type of insulation-induced injury is fiberglass insulation. Fiberglass insulation consists of tiny glass fibers that are small enough to poke in between skin cells and can be worked rather deep into the skin. 

The human immune system reacts to such an intrusion by routing immune cells to digest the invader in situ.

To transport the immune cells to the affected area, the capillaries in the skin dilate to allow extra blood flow. This turns the skin bright red and puts pressure on touch-sensing neurons.

That, in turn, along with the tiny fibers themselves, causes an unpleasant itching sensation.

While contact with fiberglass and similar insulation a single time is unpleasant, repeated exposure can contribute to developing dangerous allergies. People who work with fibrous insulation should wear eye, airway, and skin protection.

Attracting Unwanted Pests

Some insulation materials can attract or promote the growth of life forms you do not want in your home. 

Several types of insulation, including most made of plant matter, can serve as a growth substrate for dangerous molds. Often, all mold needs to colonize a new surface is a small amount of moisture. 

Spores from mold-infested insulation can cause skin irritation, watery eyes, runny nose, sinus infections, and airway inflammation. There can also be an unpleasant, musty smell.

There have also been cases where animal pests have been attracted to building insulation. In the Pacific Northwest, carpenter ants have reportedly developed a taste for some brands of rigid foam insulation installed under residential siding. 

The ants seem to enjoy eating the foam and establishing new nests in between the rigid panels. Carpenter ants will eventually start to eat the wood used in the structure of an infested house. They will also defend their colony by biting and stinging much larger animals.

Similarly, termites are known to be attracted to some brands of cellulose-based insulation. One particular preference is cellulose-based spray foam insulation which provides both a food source and a warm colony site. 

Termites can eventually cause catastrophic damage to wood-frame structures, and their waste can release hazardous compounds as it decomposes.


There are several ways bad insulation can contribute to the development of cancer.

Volatile organic compounds used as propellants and inhaled particulate matter can damage the DNA of cells in the respiratory system, which can eventually cause lung or throat cancer. 

Similarly, the microscopic fibers that break off fiberglass and similar insulation materials can cause the growth of both benign and malignant masses in the skin and other tissues. Compounds produced by various types of mold and some insect pests share this distinction.

Does a High R-Value Contribute to Better Insulation?

The higher the R-value of an insulator, the better the insulation. This is because the relationship between insulation and R-value is positive and linear.

What does the above relationship mean? The higher the R-value you have, the less you’ll spend on heating, especially during the colder months.

What Factors Affect Insulation R-Value?

It’s worth noting that the R-value is affected by different factors. These factors can increase or decrease the value, affecting how effective the material is for insulation.

The most common factors that affect an insulator’s R-value include:

  • Environmental conditions: Different types of insulation are affected differently by weather. For instance, the R-value of fiberglass decreases as temperatures dip below 32℉ (0℃).
  • Material type: Different insulation materials have varying R-values. For example, fiberglass, cellulose, foam board, and spray foam have different thermal resistance properties, which in turn, affects the R-value.
  • Thickness: According to Science Direct, thicker insulation provides better thermal resistance and, therefore, a higher R-value. Increasing the thickness of insulation can improve its effectiveness in preventing heat transfer.
  • Installation quality: The installation process plays a crucial role in an insulator’s performance. Gaps, compression, or inadequate coverage can reduce the R-value. Proper installation is essential to maximize the insulation’s thermal resistance.
  • Air leakage: Air movement through insulation can reduce its R-value. Consequently, proper air sealing measures are essential to maintain the intended thermal resistance of the insulation.
  • Thermal bridging: Insulation can be less effective if there are thermal bridges, such as wall studs or framing members, that conduct heat through the insulation. These bridges can reduce the insulation’s overall thermal resistance.
  • Aging and settling: Over time, insulation materials may settle, compact, or degrade, reducing their R-values. Therefore, it’s important to choose insulation materials like spray foam because they are long-lasting and have minimal settling characteristics.


In conclusion, vacuum-insulated panels provide the highest R-value of all commercially available insulation.

Many other types of insulation are available to fit the needs of any homeowner. Just be careful which kind you have installed, and bad insulation can make you sick.

When it comes to evaluating efficiency, you already know that the R-value is the standard metric in insulation. I’m sure you’d be surprised if you took a deeper look into Home Insulation R-Value Vs. Cost!

Aside from the most common insulation types, Energy Efficient Patio Doors also contribute to making your more efficient in dealing with heat transfer.