How To Insulate An Attic

 One of the best ways to banish cold from your living space is attic insulation installation. Since heat rises, the attic is the logical place to install insulation. You can insulate your attic either by blowing in loose-fill cellulose insulation or by laying fiberglass batts between the ceiling joists. Installing one layer of R-19 insulation by yourself in an attic 60 feet by 40 feet will cost $2,000 to $2,500.

  • Working time: 3 to 5 days
  • Total time: 2 to 3 days
  • Skill level: Intermediate
  • Project cost: $2,000 to $2,500

Before You Start

Before beginning the insulation process, it’s highly recommended by the U.S. Department of Energy to conduct a thorough energy audit on your home. This audit helps identify areas of heat loss and inefficiency, providing valuable insights into where and how to best insulate your attic for maximum impact.

Professional Audits

A professional energy audit offers a comprehensive assessment of your home’s energy performance. This includes sophisticated tests such as using an infrared camera to detect heat leaks, conducting blower door tests to measure air infiltration, checking furnace efficiency with specialized meters, and performing surface and ambient air temperature readings. Qualified technicians will also conduct a visual inspection to identify insulation gaps and other issues. The average cost of a professional energy audit ranges from $400 to $500, depending on the extent of services provided.

DIY Audits

For those who prefer a DIY approach, conducting a basic visual energy audit of the attic can be a good starting point. This involves checking if the attic door is insulated from the top side and ensuring there is adequate weatherstripping around the access door. Additionally, inspect for caulking or expanding foam around pipes, ducts, and other potential air leaks. These simple checks can help identify areas that may benefit from insulation or air sealing.

When to Insulate an Attic

The ideal time to insulate an attic is before the onset of cold weather, allowing you to maximize energy savings throughout the heating season. However, given the extreme heat that attics can experience in summer, it’s advisable to choose a mild, temperate period for installation, typically during the transition from summer to fall. This timing ensures comfortable working conditions while preparing your home for the colder months ahead.

Fiberglass Batts or Rolls vs. Blown-In Insulation

When it comes to DIY attic insulation, fiberglass batts or rolls and blown-in cellulose insulation are popular options. Fiberglass batts are favored by many DIYers for their ease of installation and affordability. They involve laying down strips or rolls of insulation between the attic joists, making it relatively straightforward to achieve the desired depth and R-value. Fiberglass batts can be layered to increase insulation effectiveness, although this method requires physical handling and transportation of materials into the attic.

Fiberglass Batts/Rolls

Installing fiberglass batts involves carefully placing strips or unrolling rolls of insulation between the attic joists. This method allows for easy customization to fit between standard joist spacing. Fiberglass batts are generally simple to work with, as they can be cut with a utility knife to the desired size and shape. It’s important to wear appropriate protective gear, including gloves, long sleeves, and a mask, to minimize exposure to fiberglass particles.

Blown-In Insulation

Blown-in cellulose insulation is another effective method for attic insulation but requires specialized equipment. A blower machine located on the ground forces cellulose insulation through a hose into the attic, allowing for comprehensive coverage even in hard-to-reach areas. While this method may be more challenging for DIYers due to equipment rental and difficulty in assessing insulation depth, it offers excellent thermal performance when installed correctly.

Safety Considerations

Working in an attic requires careful attention to safety. Always wear appropriate protective gear, including a respirator or mask, gloves, long sleeves, and eye protection, to guard against airborne particles and potential irritants. Be cautious of protruding nails from the roof structure and use plywood boards to distribute weight evenly on ceiling joists to prevent accidental falls.

Tools and Materials

Gather all necessary tools and materials before starting the insulation project. Essential tools include a utility knife, caulking gun, cordless drill, staple gun, tape measure, flashlight, ladder, and work light. Materials typically include R-19 fiberglass insulation, attic vent chutes, caulk, expanding foam insulation, and two-by-fours for creating barriers around heat-producing fixtures.

Instructions for Installing Fiberglass Batts/Rolls

  1. Access Attic: Safely access the attic using a sturdy ladder and ensure adequate lighting for visibility.
  2. Seal Air Intrusions: Use caulking or expanding foam to seal gaps around vents, pipes, and other penetrations to minimize air leakage.
  3. Protect Heat-Producing Items: Insulate around heat-producing fixtures such as recessed lights to prevent contact with insulation.
  4. Install Attic Vent Chutes: Place foam attic vent chutes between rafters to maintain airflow from soffit vents to the attic space.
  5. Measure and Cut Insulation: Measure the space between joists and cut fiberglass batts to fit snugly without compression. Use a straight edge to ensure clean cuts.
  6. Lay Out Insulation: Lay down fiberglass batts or rolls perpendicular to the joists, ensuring full coverage and avoiding gaps or overlaps.
  7. Add Second Layer (Optional): For increased insulation, consider adding a second layer of fiberglass batts perpendicular to the first layer. This step can significantly improve thermal performance.

When to Seek Professional Help

While DIY installation of fiberglass batts is manageable for many homeowners, blown-in insulation requires specialized equipment and expertise. If considering blown-in insulation, it’s often best to hire professionals to ensure proper installation and optimal energy efficiency. Professional contractors have the experience and equipment needed to tackle attic insulation safely and effectively.


Insulating your attic is a practical and cost-effective way to enhance energy efficiency, improve comfort, and reduce heating costs in your home. Whether you choose fiberglass batts or blown-in cellulose insulation, proper installation is key to maximizing insulation effectiveness. Conducting a thorough energy audit before insulation helps identify areas for improvement and ensures that your efforts yield the best results. By following safety guidelines and utilizing the recommended tools and materials, you can successfully insulate your attic and enjoy a more comfortable living space year-round. If unsure about the process or considering blown-in insulation, consulting with professionals can provide peace of mind and optimal insulation performance. Ultimately, investing in attic insulation is a valuable step towards creating a more energy-efficient and comfortable home environment.

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