How To Choose Insulation



According to the U.S. Department of Energy, 50% to 70% of the energy used in homes is for heating or cooling activities. By properly insulating your home, you can create a more comfortable and consistent indoor climate while significantly improving your home's energy efficiency.  This buying guide will help you learn about the different types of insulation used in residential construction, and give you the knowledge and confidence necessary to make the right purchase decision to meet your home insulation needs.

Insulating your roof or ceiling will help keep your home at a pleasant temperature while saving you money on energy bills. With energy costs on the rise, maximizing the energy efficiency of your home is more important than ever before.

How to Select Insulation


1. Determine where additional insulation is needed
2. Determine what R Valve you need for maximum insulation efficiency
3. Determine the type of insulation you need
4. Calculate the quantity of insulation you should buy


Insulation: Where, What and How


Heat constantly travels towards cooler areas. Insulation works by decreasing the amount of heat entering from outside when it’s hot, and trapping warmth inside when it’s cold outside. The highest proportion of heat transfer occurs through the roof and ceiling, so it’s most important to insulate in those areas.


Most homes are insulated in the attic and any floors that are located above unfinished basements or crawl spaces. The most effective places to add insulation to older homes are exterior walls, attics, basements and crawl spaces.


R Value When choosing insulation, one of the most important qualities to note is the R-value, which indicates how well insulation resists heat transfer. R-values vary based on the type, thickness and density of the material being used. Insulation with a higher R-value will perform better than insulation with a lower rating. To determine the amount of insulation you need in each area, see Insulation R-Values.

Where Form Meets Efficiency

The most common insulation types are fiberglass, cellulose and foam. These types of insulation are available in a number of different forms. The type you need will depend on which type is currently installed and the required R value.

Insulation Types and Forms 

Blown-in/Loose Fill  

Blow-in Insulation Blow-in Insulation or loose fill insulation is usually made of fiberglass or cellulose (recycled paper fiber). It is blown or sprayed into place with pneumatic equipment and is ideal for use in hard-to-reach areas, such as attics. It can also be used to fill wall cavities and can be installed over existing insulation.


Batts Batts are precut sections of fiberglass or rock wool insulation that are designed for easy handling and use between framing, such as studs and joists. Batts are available either with or without paper or aluminum foil facing. They can be used in floors, walls, attics and ceilings.


Rolls Like batt insulation, rolls are available in pre-cut widths to fit between studs and joists, but come in longer continuous lengths ranging from 20 to 40 linear feet. This makes rolled insulation an excellent choice for attics, floors and other areas where longer runs are needed.

Foam Board

Foam Board Foam board insulation, or rigid panels of insulation can be used to insulate almost any part of your home, from the roof down to the foundation. Polystyrene and polyurethane are the most common types of materials used in making foam board. Foam board insulation sheathing reduces heat conduction through structural elements like wood and steel studs.

Spray Foam

Spray Foam Latex or polyurethane spray foam is sprayed into place with a spray can or specially designed equipment. Spray foam can be used to fill small gaps and cracks and is ideal for sealing around doors, windows and vents. Special equipment to apply foam to larger areas. Spray foam sets quickly and can be trimmed, painted or stained.

Vapor Barriers

House wraps and kraft faced insulation are examples of vapor barriers that help control the amount of moisture that passes through the insulation. If moisture from either direction is allowed to build up within stud or cavity walls, the heat-conducting moisture will cause the insulation will lose its R-value and allow mold and rot to set in over time. Vapor barriers are most commonly used when framing the exterior walls of a house.

 Calculating the Costs of Insulation


Step 1- Determine If Your Home Is Already Insulated

First, determine if you already have insulation installed, and where. If you do have insulation, find out the type and compare it to industry standards. Manufacturers determine the value by the R-value or number; the higher the R-value, the better the insulation works.

Step 2 - Calculate Any Additional Insulation Needs

Calculate additional needs. Measure the depth of your current insulation. R-38 is the industry standard. The minimum thickness for R-38 is 12-inches. If your current insulation is only 5-inches deep, you will need to add 7-inches of insulation to achieve the 12-inch R-38 rating.

Step 3 - Measure the Area Needing Insulation

Measure the length and with of the area you need to insulate. Multiply the length times the width to determine the square footage of the space.

Step 4 - Determine the Type of Insulation to Use

Decide what type of insulation you want to use. Cellulose insulation is calculated based on the depth of the blown in insulation. Fiberglass insulation is calculated based on the number of batts or rolls you will need. Blown-in insulation requires the least amount of work, but requires special tools and equipment.  Fiberglass insulation in rolls or batts can easily be installed by the homeowner.
You may rent the equipment and install it yourself, or hire a professional to do the job.

Other Options


For more information on estimates and pricing please refer to our online Insulation Calculator. Existing structures may require more insulation than new constructions. Calculations are based on the heat source of your home, the location and the size and square footage of the area to be insulated.

If you prefer to hire a professional, The Home Depot Home Services offers free in-home consultations in addition to several types of insulation options to help you choose the best solution for your home.

Other Areas to Consider


Another way to control heat loss and gain is by improving the quality of your windows. Low emissivity or Low-E windows do not allow as much heat to pass through, keeping your house cooler when it’s hot and warmer when it’s cold.

Hot Water Heaters

Insulate water heaters to prevent costly energy loss. Look for insulating pre-cut jackets or blankets with an insulating value of at least R-8. Adding insulation to your water heater can reduce standby heat losses by 25%–45%. This will save you around 4%–9% in water heating costs.

Hot Water Pipes

Wrap pipes with tubular insulation to prevent freezing and help keep water hot. Use quality pipe insulation wrap. Insulating your hot water pipes reduces heat loss and can raise water temperature 2ºF–4ºF hotter than uninsulated pipes allowing you to use a lower temperature setting.

Vent Ducts

Insulated heating and air conditioning ducts operate more efficiently and vibrate less, reducing noise. Properly insulating air ducts located in unconditioned spaces such as attics, crawl spaces, garages, or unfinished basements can help improve your home's energy efficiency.

Installation Tips and Tools


Batts and rolls are available in widths suited to standard spacing of wall studs, and attic or floor joists. Continuous rolls can be hand-cut and trimmed to fit. Loose Fill or blown-in insulation comes with instructions on the bag. The manufacturer will specify the amount of insulation required to obtain a particular R-value per square foot of space. 




As always, it helps to have the right tools for the job. The basic tools you need are a tape measure, utility knife, straight edge, lightweight stapler or hammer tacker to secure insulation in place and a putty knife. Additional materials may include a drywall compound and expanding foam sealer.

It's also a great idea to bring a portable light, especially when working in attics and crawl spaces, plywood to stand on, a rake for insulation adjustment, and insulation supports. All these tools and materials will come in handy during your project.


Before You Insulate


First, make sure that your house is properly ventilated. Adequate ventilation is necessary to prevent too much heat and condensation from building up as well as to provide fresh air. Next, plug leaks to prevent air from getting in and out in areas such as around windows and doors. Always fix leaks before installing insulation, as they may be difficult to find after the job is finished.




Working with insulation can cause itching and skin irritation, so make sure you take proper safety precautions. Wear long sleeves and pants, work gloves, safety glasses, and a dust mask or respirator to avoid irritating your skin or breathing in harmful substances. Vacuum your clothing immediately after to help reduce the chances of skin irritation.