Insulation helps to keep warm air inside during the winter and cool air inside during the summer, reducing the need for heating and cooling systems.

Insulation Materials

When retrofitting existing walls with insulation, common materials used are cellulose, fiberglass, and Urea-Formaldehyde Foam Insulation (UFFI). Each material has pros and cons.

Cellulose: Cellulose insulation is an environmentally friendly option made from recycled paper treated with fire-retardant chemicals. It offers a relatively high thermal resistance (R-value) per inch, making it effective at reducing heat transfer. Cellulose insulation is adept at sound insulation, providing a good solution for soundproofing. It is cost-effective, making it an attractive choice. However, cellulose insulation is sensitive to moisture, potentially leading to mold growth and diminished performance if it becomes wet. Proper installation and density are crucial to mitigate issues such as settling over time.

Fiberglass: Fiberglass insulation is non-absorbent, making it less susceptible to moisture-related problems. Its lightweight nature simplifies the installation process and reduces stress on wall structures. Fiberglass insulation is non-combustible and does not contribute to the spread of fires. When installed correctly, it can maintain its R-value over time without settling. However, fiberglass insulation typically has a lower R-value per inch compared to cellulose, meaning that thicker insulation may be required to achieve the desired thermal resistance. The fine glass fibers in can irritate the skin, eyes, and respiratory system during installation. There can also be some potential for air infiltration if not installed carefully.

Urea-Formaldehyde Foam Insulation (UFFI): UFFI, was used in the past because it can be easily blown into existing wall spaces, but is now considered problematic due to health concerns. UFFI can release formaldehyde gas over time, which can have adverse health effects. UFFI use was banned in the US in 1982, though the ban was overturned on appeal in 1983. If your home has UFFI insulation, it is often advisable to have it professionally removed and replaced with a safer insulation material.

How to Choose and Use Insulation | This Old House

Adding Insulation to Your Attic

The cost of adding insulation to your attic is influenced by the type of insulation chosen, with options like fiberglass batts, blown-in cellulose, spray foam, and rigid foam boards, each carrying a different price tag. Attic plays a significant role, as a larger attic requires more insulation.

Another factor is labor costs, which depends on whether you hire a professional contractor or do the work yourself. Accessibility to your attic also matters, with challenging access or obstructions potentially increasing labor expenses.

The desired R-value (the level of insulation) and any necessary ventilation or air sealing work can impact the total cost. Local building codes may also require specific insulation levels or materials, further influencing the budget.

How to Install Fiberglass Insulation

This Old House host Kevin O'Connor shows how to fill gaps and make a space an addition or remodel more cozy and energy efficient.

Payback Period for Adding Insulation

The payback period for attic insulation hinges on energy savings achieved. Enhanced attic insulation typically leads to substantial energy savings by reducing heating and cooling expenses. The payback period can range from a few years to over a decade, depending on factors like your energy consumption patterns, the cost of insulation, and your local climate.

An energy audit can help you calculate potential energy savings more accurately. Explore any available incentives, rebates, or tax credits for energy-efficient home improvements.