Attic Insulation is an Important Part of a High-Performance Home

Attic Insulation – the Basics to a High Performing Home

Contrary to common belief, a high‐performing home or good building science is not necessarily expensive and unattainable to the consumer. Many basic practices are available that can achieve a better performance for your home.

There are numerous uncomplicated techniques in construction which can make a huge difference in the performance of your home.

Consider sealing and insulation in the attic space as a basic practice. There are many variations to insulate attic spaces from improving the performance for remodel projects to new construction. Plus, placing attic insulation at the rafter level to allow for a semi‐conditioned space in the attic area.

Attic Insulation High Performance Home Details

The High Performance homes team has created four details for your convenience. Each detail is a variation on how you might consider insulating your attic. As a member of the AIBD, you have free access to these details and more details pertaining to high performing homes.

Horizontal Method

The first detail at the upper left is a simple horizontal method of insulating attic space. This is probably the simplest and least expensive method for insulating your attic.

Plus, it keeps your home warm and cool.

If you choose to use this method, it is important to not place your HVAC equipment on the celling rafters. Or even worse, using the attic space as storage. This method breaks up the insulation depth needed for protecting your home.

Ceiling Coffers and Interior Vaults

At the upper right, the condition is similar. The difference we see is how to insulate when ceiling coffers or interior vaults are a part of the structure. Again, maintain continuous insulation without other obstacles to interfere with the insulation depth.

Attic Insulation in the Rafters

The lower left detail is an even better detail, and the cost becomes a little more expensive. This detail shows the insulation tucked into the rafters. This allows the attic space to become a part of the building envelope. In this case, equipment and storage or other uses can be utilized in the attic space.

Plus, this method allows for a better heat and cool condition for the main living spaces below the attic.

The lower right detail is like the lower left in that the insulation is tucked into the rafters. In this case, into knee walls in the attic creating a habitable space in the attic.

Vapor Barriers

The first two details at the top require an effective vapor barrier between the insulation and ceiling material. For the two lower details, you must design the important detail of ventilation into the rafter space.

An effectively ventilated roof needs a one‐inch airspace from the soffit to the ridge. Achieve this by designing a continuous air chute in each rafter bay. Air chutes, when combined with soffit vents and a ridge vent, will help prevent problems with condensation and ice dams.

Caulking and Sealing

Always remember that tight caulking and sealing is needed to complete effective insulating. And tight homes require good ventilation. Check out the High Performance Homes Team blog on Caulking and Sealing – the Basics to a High Performing Home.

More about the High Performance Homes Team

The American Institute of Building Design (AIBD) encourages the design and building of High Performance Homes. The AIBD High Performance Homes Team is creating blogs that guide you as the designer in good practices for high‐performing homes.

The High Performance Homes Team strives to be the resource for designers, builders and consumers in the quest to design and build energy efficient, comfortable, and environmentally safe homes. If you would like to be a part of the AIBD High Performance Homes Team, contact AIBD at

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