Best Attic and Crawl Space Insulation Options

A few attic and crawl space insulation options are available. Poor insulation can reduce your comfort and cause you to spend more on heating and cooling. But the best type depends on your home. We’ll look at the most common types of attic insulation and insulating materials best suited for crawl spaces so you can make an informed decision.

Common Home Insulation Materials

Insulation prevents drafts and the transfer of heat and moisture. Since heat naturally rises, the attic is one of the most important areas to insulate. Each type of insulation has pros and cons and is not suited for every situation. These are the top choices, although the best depends on your needs, budget, and local climate.

Spray Foam Insulation

Spray foam is the only liquid-based insulation. It has many benefits, including ease of application. The material is sprayed into place, where it thickens and grows, filling any gaps or spaces where heat can escape. It forms a durable, airtight seal.

An insulation’s R-value measures its ability to resist the movement of heat (the higher the number, the better a material’s thermal performance). Spray foam has an R-value of 5.6 to 8, which makes it an effective insulator. Other benefits of using it include:

  • Spray foam maintains its quality over time
  • The foam provides some structural support
  • No vapor barrier, so the foam won’t trap moisture
  • A Class-1 Fire Rating
  • Resistance to mold and mildew growth
  • Doesn’t provide a food source for pests

The higher cost of spray foam insulation is offset by its energy efficiency. Precautions are recommended during installation; a mask, respirator, and goggles should be worn. The materials in the foam can irritate your skin. We suggest letting a professional install spray foam insulation, as they understand the complexities involved.

Foam Board Insulation

Rigid foam boards are great for insulating basements and are preferred for crawl space insulation. They are suited for insulating foundation walls. Sealing the joints between the boards prevents air passage, while rigid foam:

  • Is non-water absorbent
  • Doesn’t support mold growth 
  • Provides a high level of energy efficiency

Available in standard sizes, foam boards are easy to cut to fit. This usually requires a circular saw and masonry blade, but sometimes a utility knife can be used to score the material; then you can snap it apart. It’s also easily attached with screws or a special adhesive. Smaller pieces can be sealed with caulk or spray foam.

The types of foam board insulation include:

  • Expanded polystyrene (EPS): EPS is the cheapest form and the same material as disposable coffee cups. However, it only has an R-value of 4 per inch of thickness.
  • Extruded Polystyrene: A denser material available in pink or blue panels, it has an R-value of 5 per inch of thickness. Panels with tongue-and-groove edges limit air movement.
  • Polyiso (Polyisocyanurate): This more costly material provides an R-value of 6 per inch of thickness. Various thicknesses are available, and the material is often foil-faced to reflect heat.

Fiberglass Batt Insulation

The most common type of attic insulation, fiberglass batts have a recognizable pink cotton candy or cloud appearance. They consist of tiny glass fibers produced via heat from recycled material and sand. The fibers are rolled into large sheets fused by a chemical vapor.

The benefits of fiberglass batt insulation, and why it’s such a popular option, include:

  • Production from a renewable energy source (sand).
  • A flame-proof vapor barrier can slow the spread of fires.
  • Air pockets prevent the material from shrinking or collapsing.
  • It is soundproof, reducing internal and external noises.
  • DIY installation is possible.

While many people don’t need a professional to install fiberglass batt insulation, it doesn’t come without risks. The glass in the material can cause injury, while the vapor from the barrier can be harmful (wearing gloves and a mask protects you from harm). 

Other downsides to this insulation include reduced performance if it gets wet. Fiberglass batts take a long time to dry and can breed mold after absorbing moisture. The insulation is also attractive to rodents and other pests.

Blown-In Fiberglass Insulation

Blown-in fiberglass insulation is also available. The base material is the same as with batts (without the vapor). It is installed using a blowing machine. In addition, blown-in fiberglass insulation provides an airtight layer, filling cracks or gaps to limit the movement of hot or cold air. It also has sound-insulating properties.

Other perks include:

  • Faster Installation: The blown-in method is quicker than installing fiberglass batts. Rather than days, it takes just hours. 
  • Improved Air Quality: The absence of a vapor improves indoor air quality, which is beneficial for people with allergies.
  • Proper Care Maintains Efficiency: With routine maintenance, you can prevent the R-value from decreasing due to settling.

Blown-In Cellulose Insulation

This attic insulation is also applied using a blowing machine. It consists of recycled wood, cardboard, newspapers, and other materials, which are made flameproof with boric acid and other substances. Blowing the material in fills spaces and gaps in attic walls. 

Blown-in cellulose is eco-friendly; no new material needs to be produced and it can be reused. It also has a 23% higher R-value than fiberglass batts. Wind-washing is reduced as well. This phenomenon is when insulation is pushed away from the edges, which reduces thermal performance.

These advantages help offset cons such as messy installation. The cellulose should also be kept dry. Any dampness can allow mold to grow. Such a situation takes much time and effort to resolve, as the insulation must be cleaned up bit by bit.

How Do I Choose the Right Insulation?

The best insulation to choose depends on where you’re installing it. Foam boards are best for crawl spaces. Also, think about how you’re using the space. Consider properties such as the type of material, its thickness, insulating value, sound absorption, energy efficiency, and ability to control moisture. However, if you intend to turn your attic into a living space, you may want to insulate the roof instead. 

How Do I Find the Best R-value for Insulation?

The level of heat resistance you need depends on your home’s location and climate. The U.S. Environmental Protection Agency (EPA) has established eight climate zones across the country. The recommendations for insulation efficiency in an attic, floor, etc. vary depending on the zone you live in. Generally, the farther north you live, the colder your location, and the higher in altitude you are, the higher the R-value you’ll need.

How Do I Know My Home Needs More Insulation?

Signs your home is under-insulated include a sudden increase in energy bills, meaning your HVAC system is working harder. Cold spots, especially near windows and doors, can mean air is leaking through cracks or seams. Hearing lots of noise from outside can mean your walls and ceilings need to be better insulated.

Contact Trio Heating & Air

When it comes to attic and crawl space insulation, there are a few ways to consider your options. Choosing the right insulation requires knowledge of available materials and your home. We can install various types of insulation to regulate indoor temperatures. Our team can also help you take advantage of moisture control, sound dampening, and energy savings as well as insulation rebates, coupons, and tax credits. Call (415) 223-5096 to learn more and request help with crawl space and attic insulation.

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