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 the flow of heat 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, explains what an R-value is, and also answers 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 insulation with the highest R-Values, with a few exceptions, is rigid foam or panel insulation. 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 exteriors as well as in 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?

While foam board insulation is pretty light in weight, it doesn’t make a ton of sense to have it shipped to you due to its bulkiness, unless you ship in small more expensive pieces due to maybe not having any stock near you locally.

Home Depot carries different types of affordable foam board and it’s usually in stock. The sheets are usually in 4x8ft cutouts rectangle sizes (pretty big) – but bring or buy a basic utility knife with you to cut it up in the store if you need to fit small pieces in your car.

Lowes also has a few key foam board insulation products that you can readily pick up. You can check those out by clicking here.

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 –

*While we’re not tied to one brand or another, this section does contain some affiliate links to help support the blog. The links are pointing to what we feel is the easiest way to purchase the foam boards.

ProductDetailsRough Cost
RMAXPro Select R-Matte Plus-3, 3/4 in. x 4 ft. x 8 ft. R-5.0 Foam Insulation Board3/4 inch thick R-5$17
FOAMULAR 150 1 in. x 4 ft. x 8 ft. R-5 Scored Square Edge Rigid Foam Board Insulation Sheathing1 inch thick R-5$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 type of insulation for adding additional insulation to 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.

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 DIYer’s, 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 might do the trick.

The cheapest way to go will be to pick them up locally at Home Depot. It’s called Gaps and Cracks and comes in a 16oz can. It’s definitely for smaller areas and projects, but it’ll be the most affordable way to go vs. shipping it.

You can ship it from Home Depot, but Amazon has similar cans for a bit more cost:

For slightly larger projects, this is a good kit for a bundle package. It’s 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. You can check that out here:

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 like we all do for most things.

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

Blanket: Batts and Rolls

Blanket insulation, often sold in units called “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) Batts3-3.85

Where to Buy Fiberglass Insulation?

The easiest and most readily available place to buy fiberglass insulation is a store like Home Depot.

As of this writing, they have two main options, both of which are good depending on what R value you’ll need and how much space you have to fill in.

Home Depot's listing of a roll of R-13 fiberglass insulation

The first is a Kraft (paper) faced R-13 fiberglass roll that comes in different sizes. You can see those here.

Home Depot's listing of a roll of R-30 fiberglass insulation

The second is a Kraft (paper) faced R-30 roll that is more expensive, but you get the much higher R-value. You can see those here.

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 an excellent insulating blanket when you spray it in.

Where To Buy Loose Fill Cellulose Insulation?

The go-to for the easiest way to order would be Home Depot again. The product is called Greenfiber Cellulose Blown-In Insulation in 25lb bags. At least locally here in Florida, Home Depot also offers a free blower machine rental if you order over 20 bags as well.

a 25lb bag of Greenfiber cellulose Insulation that says All New Greenfiber across the top

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 different 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, and can 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 which 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 the development of 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 the residential siding. 

The ants seem to enjoy eating the foam and establish 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.


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.


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