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Where & How Much Attic Insulation Do You Need?

Posted on : May 5, 2024

Where & How Much Attic Insulation Do You Need?

Attic insulation is a material installed in a home's attic space that provides a barrier to prevent heat transfer between the living areas and the attic. We often get questions like what areas of an attic require insulation, how much attic insulation is needed, and how much it costs to insulate an attic. 

At McClellands Contracting and Roofing, we do our best to provide insights into different components of your roofing system. In this blog post, we have compiled valuable information about your home’s insulation, including answers to the questions above.

What Is The Role Of Attic Insulation?

Attic insulation is extremely important for your home, adding both value and comfort. Insulating your attic is crucial for maintaining a balanced temperature in your home. 

Insulating your attic brings the following benefits to your home or living space:

  1. Prevents heat loss/gain through the attic space.
  2. Increases energy efficiency and lowers utility bills.
  3. Improves indoor comfort by regulating temperatures.
  4. Stops drafts and air leaks through the attic.
  5. Reduces strain on heating/cooling systems.
  6. Creates a more eco-friendly, sustainable home.
  7. Enhances soundproofing between floors.
  8. Adds resale value to the home.
  9. May qualify for energy rebates or tax credits in some areas.
Attic Insulation

Where To Insulate In The Attic

Heat can easily escape or enter your living spaces, so proper insulation is crucial. Here are some key areas in your attic that require proper insulation for a balanced temperature.

1. Attic Floor

The attic floor is the horizontal surface that separates your living space from the attic area above. It's one of the most important areas to insulate because heat naturally rises. Without proper insulation, you could be losing a tremendous amount of warm air into the attic space in the winter and gaining heat in the upper levels of your home in the summer. Insulating the attic floor creates a thermal barrier that helps keep conditioned air inside your living area.

Attic Floor

2. Attic Hatch or Door 

The attic hatch or door is the entry point into the attic from your living space below. This area is often overlooked but can cause air leaks and heat transfer if not properly insulated. The attic hatch should be insulated with rigid foam insulation or insulation batts and also weather-stripped to prevent drafts.

Attic Hatch or Door

3. Knee Walls

Knee walls are short, vertical walls with attic space directly behind them. They are commonly found in rooms with sloped ceilings, like bonus rooms or finished attic spaces. Knee walls must be insulated because the attic space behind them can allow heat or cold to transfer through if they are left uninsulated. Insulating knee walls prevents this transfer and helps regulate temperatures.

4. Rafters

If a heating or cooling system is installed in an unfinished attic, insulate the rafters to convert the area into a conditioned space. In a finished attic room or dormer, insulate between the rafters and studs of your exterior wall for better temperature regulation.


How Much Attic Insulation Do You Need?

According to Energy Star, the recommended insulation level for residential attics is R-38, which typically equates to 10-14 inches of insulation thickness, depending on the insulation type. Generally, the insulation needed depends on your climate and the material used. 

A quick method to see if you need additional attic insulation is to look across the breadth of your attic floor: 

  • If the insulation is level with or below the floor joists (which means they are visible), you should add extra insulation.
  • If the insulation is much above the joists and completely covers them, you probably have enough, and adding more may not be cost-effective.
Attic Insulation Do You Need

How To Insulate An Attic Properly

Insulating an attic involves clearing the area, sealing air leaks, laying down insulation batts or blown-in insulation to the recommended R-value, and ensuring proper ventilation. By following certain steps, you can insulate your attic:

1. Prepare the Attic

  • Remove any existing insulation, debris, and clutter from the attic space. 
  • Identify and seal all air leaks around plumbing stacks, electrical boxes, exhaust fans, and the attic hatch using caulk or spray foam sealant. 
  • Seal gaps in the attic floor to prevent air leakage between living spaces and the attic.

2. Insulate the Attic Hatch/Door

  • Attach the insulation securely using adhesive or mechanical fasteners precisely to the attic door or hatch. 
  • Weatherstrip around the hatch or door to create an airtight seal when closed. This prevents the cool air from leaving and unconditioned air from coming into the home.
  • Additionally, insulate the knee walls, if any.

3. Install Rafter Vents (if needed)

  • Rafter vents are essential for allowing insulation to extend to the edge of the exterior walls, ensuring proper coverage.
  • Install these vents along the eaves before laying insulation to maintain adequate airflow and prevent moisture buildup.

4. Lay Insulation Over the Attic Floor

  • Roll out batts or blow in loose-fill insulation evenly across the attic floor.
  • Ensure the insulation is level with or slightly above the attic floor joists. 
  • Aim for a consistent depth throughout for even coverage.

5. Complete Insulation Coverage

  • After addressing the main areas, inspect for any remaining gaps or obstructions like around plumbing, wiring, or chimneys.
  • Cut batts to fit these spaces and stuff them in tightly, ensuring uniform insulation depth throughout the entire attic space. 
  • Double-check for any missed areas to maximize coverage.

6. Final Housekeeping

  • Once the insulation is complete, replace the attic hatch or door.
  • Install attic rulers to monitor insulation levels over time and ensure they are maintained.
  • Verify that adequate attic ventilation exists from the soffits to the roof ridge to prevent moisture buildup and promote airflow.

How Much Does It Cost To Insulate An Attic?

The exact cost to insulate an attic can differ based on the size of your attic, the type of insulation used, and whether you need any prep work done. On average, you can expect to pay between $1 to $7 per square foot, including the labor and materials. Here is a rough cost estimation of different types of attic insulation:

1. Fiberglass Batt Insulation

Cost per square foot: $0.40 - $1.50

Fiberglass batt insulation is one of the most common and economical options. Prices can vary based on the R-value and thickness.

2. Blown-In Fiberglass Insulation

Cost per square foot: $0.50 - $2

Blown-in fiberglass is a popular choice for attics as it can easily fill irregular spaces and cavities. Costs depend on the desired R-value and depth.

3. Cellulose Insulation

Cost per square foot: $0.60 - $2.30

Made from recycled materials, cellulose insulation is an eco-friendly option. Costs vary based on the required thickness and whether it's loose-fill or dense-pack.

4. Spray Foam Insulation

Cost per square foot: $0.50 - $7

Spray foam insulation provides an excellent barrier and air sealing but is more expensive. Costs depend on the type (open-cell or closed-cell) and thickness.

5. Rigid Foam Board Insulation

Cost per square foot: $0.60 - $2

Rigid foam boards are effective for insulating attic hatches, knee walls, and other irregular spaces. Prices vary based on the material (XPS, EPS, or polyiso) and the size of the boards.

6. Mineral Wool Insulation

Cost per square foot: $1.40 - $2.50

Mineral wool (rock wool or slag wool) is a durable and fire-resistant option for attics. Costs depend on the desired R-value and thickness.

Also Read: 5 Best Attic Insulation Options in 2024 (Pros & Cons)

DIY vs. Professional Insulation Installation

When it comes to insulating an attic, professional insulation installation offers numerous advantages over a DIY approach. While DIY may seem appealing due to lower upfront costs, it carries significantly more cons. DIYers may struggle with proper techniques, handling materials safely, achieving consistent coverage, sealing air leaks effectively, and meeting code requirements. Most crucially, DIY work lacks the expertise, warranties, and quality assurance that professionals provide. 

Conversely, professional installation ensures efficient and code-compliant insulation, proper air sealing, and ventilation and often includes warranties. Professional roofers will handle and install the materials efficiently, avoiding any mistakes. If you hire a professional roofer or contractor for your attic’s insulation, it will be less time-consuming as they have previous experience, which makes the process faster. For homeowners who have never insulated  space, hiring a professional is a comparatively more reliable and effective option, minimizing risks and maximizing energy efficiency. 

DIY vs. Professional Insulation Installation

Call Us For Roof Replacement Services In Pittsburgh

When it comes to the best attic insulation solutions in Pittsburgh, trust our experts at McClellands Contracting and Roofing. Our team of professional roofers will thoroughly inspect your attic, provide a customized quote, and perfectly install the insulation system that will maximize energy efficiency and indoor comfort year-round. 

With a focus on exceptional roofing services and customer satisfaction, we'll ensure your home has an effective insulation system that keeps it cozy no matter the weather. To book a free consultation or discuss your project, call us at (412) 353-5660.

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