What are the main differences between blown-in and batt insulation for attics?

Blown-in insulation is loose-fill, ideal for irregular spaces, while batt insulation comes in pre-cut panels for standard joist spacing. Blown-in fills gaps more effectively, offering better air sealing, while batts require careful fitting to avoid air pockets.

Which type of insulation is easier to install for a DIY attic project?

Batt insulation is generally considered easier for DIY installation in attics with consistent joist spacing, as it requires no specialized equipment. Blown-in insulation often necessitates renting a blowing machine, adding complexity to the DIY process, although some home improvement stores loan them out for free to homeowners who are buying large quantities of insulation.

How do the costs of blown-in and batt insulation compare for DIY attic insulation?

Batt insulation typically has lower upfront material costs for DIY projects. Blown-in insulation may have similar material costs, but often includes the added expense of renting a blowing machine, though some stores offer free rentals with a minimum purchase.

What R-value can I expect from blown-in versus batt insulation in my attic?

Blown-in insulation can achieve R-values of 2.2 to 3.8 per inch (fiberglass) or 3.2 to 3.8 per inch (cellulose). Fiberglass batts typically offer R-values between 2.9 and 4.3 per inch, with high-density options reaching higher values.

Which type of attic insulation is better for tight spaces and irregular attic shapes?

Blown-in insulation is better suited for attics with tight spaces, obstructions, and irregular shapes because it conforms to the space, filling nooks and crannies effectively. Batt insulation can be difficult to install in these areas, potentially leaving gaps and reducing overall insulation performance.

DIY Attic Insulation: Batt vs. Blown-In

By Home Sidekick Team June 02, 2025 8 min read 1568 words

insulationatticDIYhome improvementenergy efficiencybatt insulationblown-in insulation

A poorly insulated attic is like leaving a window open year-round – you're throwing money away! Heating and cooling costs skyrocket when your attic can't effectively regulate temperature. As a savvy homeowner, you might be considering tackling attic insulation as a DIY project. Two of the most popular methods are batt and blown-in insulation. But which is right for you? This comprehensive guide breaks down the pros, cons, and installation process of each, helping you make an informed decision to boost your home's energy efficiency and save on utility bills.

Batt Insulation: The Traditional Approach

Batt insulation, typically made of fiberglass, mineral wool, or even cotton, comes in pre-cut panels designed to fit between standard studs and joists. It's a readily available and relatively inexpensive option, making it a favorite for DIYers.

Pros of Batt Insulation:

DIY-Friendly Installation: Batt insulation is generally easy to handle and install, requiring minimal specialized tools. You can cut it to size with a utility knife, making it adaptable to various attic configurations.
Cost-Effective: Batt insulation typically has a lower upfront material cost compared to blown-in. This makes it an attractive option for budget-conscious homeowners.
Readily Available: You can find batt insulation at most home improvement stores. This accessibility makes it convenient for immediate project needs.

Cons of Batt Insulation:

Gaps and Compression: Achieving a tight seal with batt insulation can be challenging. Gaps and compression significantly reduce its R-value (resistance to heat flow). According to the U.S. Department of Energy, even small gaps can drastically diminish insulation performance (Energy.gov).
Difficult to Install in Irregular Spaces: Attics often have odd angles, wiring, and obstructions. Fitting batt insulation snugly around these areas can be time-consuming and frustrating.
Lower R-Value per Inch Compared to Some Blown-In Options: While batt insulation can provide adequate R-value, it typically requires thicker layers than some blown-in materials to achieve the same level of insulation.
Can Sag Over Time: Gravity can cause batts to sag, especially in areas where they aren't properly supported, further reducing their effectiveness.

Installation Tips for Batt Insulation:

Measure Carefully: Accurately measure the spaces between your attic joists to ensure a snug fit.
Wear Protective Gear: Always wear gloves, a dust mask, and eye protection when handling fiberglass insulation to prevent skin and respiratory irritation.
Install with the Paper Facing Down (if applicable): If your batt insulation has a paper facing, it should face down towards the heated space below to act as a vapor retarder. Check local building codes, as in some climates the facing should not be used.
Cut Neatly Around Obstructions: Carefully cut the insulation to fit snugly around wiring, pipes, and other obstructions. Seal any gaps with caulk or expanding foam.
Avoid Compression: Don't compress the insulation to fit it into tight spaces, as this reduces its R-value. If necessary, use a thinner batt.
Consider Faced vs. Unfaced: Understand the vapor barrier requirements in your area. Faced batts have a built-in vapor retarder, while unfaced batts require a separate vapor barrier in certain climates.

Blown-In Insulation: Filling the Gaps

Blown-in insulation, typically made of fiberglass or cellulose, is installed using a blowing machine that distributes the material evenly across your attic floor. This method excels at filling gaps and creating a consistent thermal barrier.

Pros of Blown-In Insulation:

Excellent Coverage: Blown-in insulation effectively fills gaps, cracks, and crevices, creating a tight seal and minimizing air leaks. This helps to maximize energy efficiency.
Easy to Insulate Irregular Spaces: It easily conforms to odd angles, around pipes, wiring, and other obstructions, ensuring consistent coverage throughout the attic.
Higher R-Value Potential: Blown-in cellulose, in particular, often boasts a higher R-value per inch compared to fiberglass batts, allowing you to achieve greater insulation with less material.
Environmentally Friendly Options: Cellulose insulation is often made from recycled paper, making it an environmentally conscious choice.

Cons of Blown-In Insulation:

Requires Specialized Equipment: Installing blown-in insulation requires renting or purchasing a blowing machine. This adds to the initial cost and complexity of the project.
Messy Installation: The blowing process can be messy, creating dust and debris in the attic and surrounding areas. Proper preparation and ventilation are essential.
Settling Over Time: Blown-in insulation can settle over time, reducing its R-value and requiring additional insulation to maintain optimal performance.
Potential for Moisture Absorption: Cellulose insulation can absorb moisture if the attic isn't properly ventilated, leading to mold growth and reduced insulation effectiveness.
Can Be More Expensive Upfront: While the long-term energy savings can offset the initial cost, blown-in insulation often has a higher upfront material and equipment rental cost compared to batt insulation.

Installation Tips for Blown-In Insulation:

Seal Air Leaks First: Before installing blown-in insulation, thoroughly seal any air leaks in your attic, such as around recessed lights, wiring penetrations, and plumbing stacks. Use caulk, expanding foam, or weatherstripping to create an airtight barrier. This is crucial for maximizing the effectiveness of the insulation.
Use Baffles: Install rafter baffles (also known as vent chutes) to maintain proper ventilation at the eaves. These baffles prevent the insulation from blocking airflow from the soffit vents.
Rent a Quality Blower: Choose a blowing machine with sufficient power and a long enough hose to reach all areas of your attic. Follow the manufacturer's instructions carefully.
Wear Full Protective Gear: Wear a respirator, goggles, gloves, and a full-body suit to protect yourself from dust and fibers during the blowing process.
Follow Depth Markers: Use depth markers to ensure you're installing the correct amount of insulation to achieve the desired R-value. Most blowing machines have charts that indicate the required depth for different R-values.
Avoid Covering Recessed Lights: Never cover recessed lights with insulation unless they are IC-rated (Insulation Contact rated). Non-IC-rated lights can overheat and pose a fire hazard.
Ensure Proper Ventilation: Attic ventilation is crucial for preventing moisture buildup and maintaining insulation effectiveness. Ensure your attic has adequate soffit and ridge vents.

R-Value and Insulation Levels

R-value is a measure of thermal resistance, indicating how well insulation prevents heat flow. The higher the R-value, the better the insulation. The recommended R-value for attic insulation varies depending on your climate zone. The U.S. Department of Energy provides a map and recommendations for optimal R-values based on your location (Energy.gov). Generally, attics require a higher R-value than walls. Aim for an R-value of R-38 to R-60 in most attic applications.

When comparing batt and blown-in insulation, consider the R-value per inch of each material. Blown-in cellulose often has a slightly higher R-value per inch than fiberglass batts, meaning you can achieve the same level of insulation with a slightly thinner layer. However, proper installation is crucial for maximizing the R-value of any insulation material.

Cost Comparison: Batt vs. Blown-In

The cost of attic insulation depends on several factors, including the size of your attic, the type of insulation material, the R-value you're aiming for, and whether you're doing it yourself or hiring a professional. Generally, batt insulation has a lower upfront material cost compared to blown-in insulation. However, blown-in insulation may offer better long-term energy savings due to its superior coverage and ability to fill gaps.

To get an accurate cost estimate, measure your attic space and research the prices of different insulation materials and equipment rentals in your area. Factor in the cost of protective gear, sealing materials (caulk, expanding foam), and any necessary ventilation upgrades. Consider getting quotes from professional insulation contractors to compare against your DIY cost estimate.

Here's a general cost breakdown:

Batt Insulation: $0.30 - $1.50 per square foot (material only)
Blown-In Fiberglass: $1.00 - $2.00 per square foot (material only)
Blown-In Cellulose: $1.20 - $2.50 per square foot (material only)
Blower Rental: $100 - $200 per day

These are just estimates, and actual costs may vary. Remember to factor in the cost of labor if you're hiring a professional.

Making the Right Choice for Your Attic

Ultimately, the best insulation choice for your attic depends on your specific circumstances, budget, and DIY skills. Consider these factors when making your decision:

Attic Accessibility: If your attic has limited access or many obstructions, blown-in insulation may be the easier option.
Budget: Batt insulation is generally more affordable upfront, but blown-in insulation may offer better long-term energy savings.
DIY Experience: If you're comfortable with basic home improvement tasks, batt insulation is a straightforward DIY project. Blown-in insulation requires more specialized equipment and careful execution.
Climate: Consider the climate in your area and the recommended R-value for your attic.
Air Sealing: Regardless of the insulation type you choose, air sealing is crucial for maximizing energy efficiency.

Before starting any insulation project, check local building codes and regulations to ensure compliance. Proper planning and execution are essential for achieving optimal results and maximizing your energy savings.

Next Steps: Sealing, Insulating, and Saving

Improving your attic insulation is a significant step towards a more energy-efficient and comfortable home. Whether you choose batt or blown-in insulation, remember to prioritize air sealing, proper installation, and adequate ventilation. By taking the time to do it right, you can enjoy lower energy bills, a more comfortable living space, and a reduced carbon footprint. Consult with a qualified professional if you have any doubts or concerns about your DIY insulation project.

Ready to take the plunge? Start by assessing your current attic insulation, identifying air leaks, and researching the best insulation options for your needs. With a little planning and effort, you can transform your attic into an energy-saving powerhouse!