How much does attic insulation cost?

June 23, 2017 Anthony Naimo

Air loss through the attic/roof can often be a leading contributor to higher heating or cooling costs. Because of this air loss, it is commonly recommended to homeowners that they invest in insulating the attic with a high performance insulation material that retains the conditioned air within the home and limits air loss. But how much does attic insulation cost? 

Much like the cost of spray foam insulation for the whole home, the cost of attic insulation can vary depending on a number of factors. 

  • Attic Insulation Material Type - Home attic spaces can be insulated with a range of insulation materials including traditional fiberglass laid on the attic floor, traditional cellulose blown onto the attic floor and spray foam insulation which can be applied to both the attic floor or the underside of the roof deck, depending on the application requirements. If spray foam insulation is chosen, then there is a further choice of light density, open cell spray foam which has a lower per board foot cost, or closed cell, medium density spray foam which has a higher per board foot cost.
  • Labor – Handling materials such as fiberglass or spray foam insulation requires the experience of seasoned professionals who have the equipment and take safety measures for a proper and accurate installation. Proper installation of attic insulation by a professional provides piece of mind for the homeowner, so labor costs should be considered when calculating the overall attic insulation cost.
  • Removal of old materials – If replacing older or damaged insulation material, then removal of the existing materials should be considered as part of the overall cost. The labor involved in removing the existing insulation material and preparing the attic space for the new insulation material can sometimes be as much as the cost of the insulation itself.
  • Location – Building code requirements can play a significant role in determining the insulation requirements for the attic and, therefore, the cost of attic insulation. The location of the building may also dictate the type of attic – vented or unvented.
  • Total surface area – Depending on the insulation type, the attic type and the building code requirements, the total amount of insulation required will vary. The R-value required by the building code will influence the total attic insulation cost. If the insulation is applied on the floor, then the cost can be calculated against the surface area of the attic floor. Likewise, with the underside of the attic roof if spray foam insulation is used. The total roof surface area, the thickness of the foam insulation and the material type will all contribute to the overall cost.

Generally speaking, open cell spray foam can cost between $0.44 to $0.65 per board foot while closed cell foam insulation can cost between $1.00 to $1.50 per board foot. Again, these costs should be regarded as a guide only and does not include the labor involved for removal of existing attic insulation in renovation/retrofit scenarios.

What else should be considered?

The type of attic assembly plays a role in determining how much it will cost to insulate an attic. Typically in northern, colder climates of the United States and Canada, the attic assembly is vented whereas in the southern, warmer climates of the United States, unvented attic assemblies are common.

  • Vented Attics
    In a vented attic assembly, the insulation is laid on the floor of the attic space. Temperatures in vented attic spaces can range between 140oF - 160oF during summer and 30oF to -20oF during winter depending on climate.  HVAC equipment and ductwork systems are exposed to outdoor humidity and temperature extremes. This reduces HVAC efficiency and increases condensation potential. Attic ventilation is commonly used to remove heat and humidity from the attic space.
  • Unvented Attics
    Spray foam such as Icynene is applied on the underside of the roof deck to maintain even temperatures and humidity in the space. Conditioned attic spaces are generally within 5oF to 10oF of the conditioned living space below.  Conditioned attic space allows HVAC equipment to function in a more temperate space for improved performance, improved humidity control, energy efficiency and reduces the potential for condensation.

The aforementioned variables can all impact the total cost of attic insulation. A certified and experienced insulation contractor can provide a breakdown of the costs and their recommendation on which insulation material is the most effective to limit air loss and allow the home or building to maintain even temperatures throughout the year.


How does spray foam insulation perform in different attic types?

The use of spray foam insulation in vented attics offers the ability to:

  • Limit Air Leakage - Spray foam insulation in a vented attic helps limit where air leaks through the ceiling and is replaced by unconditioned outdoor air.
  • Limit Ice Dams Developing - A consistent level of insulation and air tightness, provided by spray foam like Icynene, on the attic floor helps minimize the potential of uneven heat loss and ice dam formation.
  • Air Impermeable Barrier - Spray foam helps limit air infiltration thereby limits airborne moisture accumulation, which helps reduce latent HVAC loads.

In unvented attics, spray foam insulation can work to help address:

  • Wind Driven Rain/Snow - By eliminating vents, an unvented attic helps keep wind-driven rain out of roof vents as well as snow ingress and ice dams. This also applies to wind-driven embers in areas prone to forest fires.
  • Potential Leaks - Light density spray foam is vapor permeable to allow for drainage of water and diffusion of moisture from the roof sheathing. This is critical to detect leaks and limit the risk of structural problems.
  • Air/Duct Leakage - As the HVAC and ducts are contained in the space, any duct leakage remains in the space and duct penetrations through the ceiling (attic floor) do not compromise the building’s air tightness.


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