Types of Insulation for Homeowners

There are nine types of insulation with different purposes and installation techniques. Insulation is a building material that prevents heat loss or heat gain. It’s also a valuable component in soundproofing. Some make for good DIY projects, while others require professional installers.

Types of Insulation

Proper insulation and sealing air leaks reduces heating and cooling costs by about 10% per year–an average of $200.00 annually. Insulation also provides a more comfortable living environment. Approximately 90% of US homes are under-insulated.

9 Types of Insulation and How They Work

Choosing a type of insulation is determined by three things:

  • Where – Where is the insulation needed? Or wanted?
  • R-value – R-value measures the thermal resistance of insulation products. Heat always flows towards colder areas, which means that products with higher R-values prevent more heat loss.
  • Installation – Some insulation products can only be installed during construction. Many are suitable for DIY applications, and more difficult projects are best left to professionals.

Blanket Insulation

Blanket Insulation

The most common blanket insulation is fiberglass batt. Available as individual batts–typically 48” long–or in rolls–50’ long. Fiberglass has an R-value of about 3.2 per inch and is suitable for walls, attics, floors, and ceilings. Batts friction fit between studs, rafters, ceiling, and floor joists.

Other types of batt insulation include:

  • Mineral Wool. Has about the same R-value as fiberglass insulation. It’s more expensive than fiberglass but also more moisture resistant and better at sound dampening. Mineral wool insulation is popular for noisy locations, in apartment construction, and in-home theaters.
  • Cellulose. Approximately R-4 per inch. Made of 70% recycled materials and offers excellent sound suppression qualities.
  • Natural Fibers. Sometimes called denim batts, natural fibers are manufactured from recycled cotton–typically blue jeans. The R-value is less than that of fiberglass–around R-3. Natural fiber insulation provides excellent acoustic and soundproofing qualities.

Blanket insulation is available with or without facing. The facing–typically kraft paper, but also aluminum foil or vinyl–is applied to one side of the batts and can act as a vapor barrier, radiant barrier, or air barrier.

Fiberglass insulation is less expensive than other insulations. Batts are also a simple DIY project as long as you have a properly sized product and follow the directions. The insulation value is in the dead air spaces, not the fibers – compressing the batts lowers the R-value.

Blown-In or Loose-Fill Insulation

Blown-In or Loose-Fill Insulation

Blown-in insulation is a top choice for attics, although it’s becoming more popular in walls, floors, and ceilings. It’s versatile and fills cavities and hard-to-reach spaces. It gets the name ‘blown-in’ since installation requires the use of a blower. Some of the different products include:

  • Cellulose. Cellulose insulation is chopped recycled newspaper mixed with borax for fire retardation and pest control.
  • Fiberglass. Chopped fiberglass can contain 40% – 60% recycled glass.
  • Mineral Wool. Rock wool uses a high percentage of recycled wool.
  • Polystyrene. Chopped-up polystyrene board or polystyrene beads.

Unlike fiberglass batts, loose-fill insulation retains its R-value when compressed–even by its own weight. For example, cellulose insulation can begin as R-3 per inch. But after blowing 10” in an attic, the lower 4” will be more than R-12.

Rigid Foam Insulation

Rigid Foam Insulation

Rigid foam insulation boards can be installed on most framed surfaces–interior or exterior. They can go under new siding or stucco, drywall, flooring, or drop ceilings. Rigid foam boards work well for low-slope ceilings and attic walls and provide excellent insulation to basement concrete walls. If 2” thick and sealed, they even provide a vapor barrier. Rigid foam is used to insulate flat roofs before the waterproofing product is applied.

There are three types of rigid foam board insulation:

  • Expanded Polystyrene (EPS). Least expensive. Approximately R-value 4.6 per inch. Available faced or unfaced. Faced products are considered vapor retardant. R-value does not degrade over time.
  • Extruded Polystyrene (XPS). Blue, green, or pink color. R-value 5.0 per inch. Approximately $0.42 per square foot at one inch thick. Considered a vapor retarder but will absorb moisture which may degrade R-value over time.
  • Polyisocyanurate (ISO). Approximate R-value 5.8 per inch. All ISO panels are faced. Foil-faced are considered impermeable–creating a vapor barrier. ISO R-value will also degrade slightly over time.

Concrete Block Insulation

Concrete Block Insulation

Autoclaved Aerated Concrete Blocks (AAC) are 80% air, making for a great insulation product. Used for foundations and building walls, they provide an approximate R-value of 1.25/inch or about R-10 in an 8” thick block.

Concrete block insulation is durable, frost-resistant, fire-resistant, and water-resistant. It has a Sound Transmission Class Rating (STC) of up to 60. AAC blocks are solid without interior voids. Until recently, AAC blocks have been virtually unknown in the USA, but approximately 60 % of homes in Europe use them.

Standard concrete blocks can add insulation using different methods.

  • Rigid Foam Blocks. Inserted into the hollow cores of the blocks during construction.
  • Polystyrene Bead Blocks. Up to R – 3.00 per inch. Manufactured using Portland Cement and polystyrene beads. Lightweight, easy DIY product, cuts easily, and accepts nails and screws.
  • Wood Chip Blocks. 85% wood, 15% concrete. 12” thick blocks. High insulation value. Easy DIY construction.

Spray Foam Insulation

Spray Foam Insulation

Spray foam is popular for filling the cavities around window and door frames and holes and gaps in walls. With an R-value of up to 6.5 per inch, it provides one of the best insulation values. You can find spray foam insulation available in hand-held cans or larger cans attached to a spray gun.

Spray foam is also available in industrial-sized containers for commercial application by professional installers. Sprayed into stud cavities of 2 x 6 framing, it will provide an R-value of 27.5 and add structural integrity. Foam fills all of the gaps and fits tight to electrical and mechanical wires, pipes, and fixtures, creating tight leak-proof walls, floors, and ceilings.

Types of Spray Foam

Good quality spray foam expands and cures quickly. When dry, you can cut, form, and paint it. There are two types of spray in place foams.

  • Open Cell Foam. Open-cell foams are less dense because they are simple polyurethane foams filled with air. They have a lower R-value and cost less than closed-cell foam. The typical R-value is 3.7 per inch.
  • Closed Cell Foam. Closed-cell spray foam is also made from polyurethane and features high-density closed cells filled with gas to provide expansion. Closed cell foam usually has an R-value of 5.0 per inch. But some very dense celled foam can get as high as 6.5 per inch. Closed-cell foam is very water resistant, making it ideal for moist locations like basements. It is more expensive than open-cell foam.

Rigid Fiber Board Insulation

Rigid Fiber Board Insulation

Rigid fiberboard insulation is a specialized product made to insulate HVAC ducting. Air ducts carry warm–sometimes hot–and cold air. Adequately insulated ducts reduce energy costs and make the entire system more effective.

Rigid boards are available from 1” – 2.5’ thick and have an R-value of R-5.4 per inch. According to insulationinstitute.com, there are multiple designs and styles of HVAC duct insulation. Many of the products, from boards to pipe wrap, are foil faced to contain the insulation fibers and add a reflective surface for even better R-values.

Insulating HVAC ducts eliminates condensation. It’s effective where warm air ducts pass through unheated areas. Rigid fiberboard insulation is manufactured from one of two products. Both are fire rated.

  • Fiberglass. More common and less expensive.
  • Mineral Wool. Better R-value per inch. More expensive. Better soundproofing.

Many manufacturers are making complete ducting systems of rigid fiberboard, eliminating the need to wrap metal ducting in new construction. Most older homes and many newer ones still have metal ducts that require insulating.

Radiant Barrier Insulation

Radiant Barrier Insulation

Radiant barrier insulation, or reflective insulation, does not have an R-value because it does not reduce heat conduction. It reflects heat–preventing it from traveling onward. Aluminum foil taped to south-facing windows is a reflective barrier that prevents sunlight from heating a room.

Radiant barriers are effective in warm to hot climates. In colder climates, they are not cost-effective – they may even be detrimental because they can reduce solar gain. 

Radiant reflective barriers are highly reflective materials–usually aluminum foil attached to various substrates. Some of these include kraft paper, oriented strand board (OSB), cardboard, plastic, and rigid insulation like rigid fiberboard and rigid foam insulation such as polyisocyanurate. Reflective insulation is popular in the following locations:

  • Exterior Walls. Often installed under siding to reflect heat from the sun. Either thin foil-covered plastic or as backing for insulation board.
  • Attics. The ideal attic temperature is the same as the temperature outside. Installing reflective insulation on the rafters or over the insulation will help prevent some heat gain and can reduce HVAC costs by up to 10% if ducting runs through the attic.
  • Furnace Rooms. Reflective foil keeps heat in the furnace and boiler rooms.
  • Ceilings. Shed ceilings and some vaulted ceilings have poor insulation and ventilation. Adding radiant barrier insulation makes the rooms below cooler.
  • Garages. Most garages have less insulation than homes. Reflective foil is an inexpensive way to help keep them cool.

Structural Insulated Panels

Structural Insulated Panels

Structural Insulated Panels (SIP) are prefabricated sections contractors use to build walls, floors, or ceilings. They are foam insulation boards sandwiched between oriented strand board (OSB) and shipped to the building site. SIPs are used for walls–interior and exterior, floors, roofs, and ceilings.

The US Department of Energy says SIP construction can reduce heating and air conditioning costs by as much as 14%. They are more airtight with fewer gaps and holes than conventional construction, quieter, and more energy efficient.

The insulating materials in SIPs are often polystyrene or polyisocyanurate. The manufacturing process is very important to produce a long-lasting product that does not delaminate. Typical R-values are about R-3 per inch, and the walls are either 4” or 8” thick.

Insulated Concrete Wall Forms

Insulated Concrete Wall Forms

Insulated concrete forms (ICF) replace wood or metal forms used to pour concrete basements. These forms remain part of the foundation and provide an R-value of R-20. The system consists of interconnected thick foam boards held together by plastic ties.

During construction, rebar is added, and the forms get filled with concrete. ICFs are not only used for basements but for exterior walls. The exterior foam panels are fitted with plastic strips to attach siding or stucco wire.

Since the foam can provide easy access to insects and water, ICF walls should be erected by an experienced contractor who understands the potential problems and knows how to deal with them.