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Green Basics

Roofs: Attics, Structure, Claddings

Roofs Keep Weather Out and Conditioned Air In

Green homes have roofs that are durable and energy efficient

Choose roofing products that are manufactured with minimal environmental impact. A roof’s performance and longevity are affected not only by the choice of roofing material, but also by all of the other materials in the roof assembly and the care with which they are assembled.

There are a number of structural options: Structural insulated panels (SIPs) combine insulation and structure and are often combined with timber framing to produce beautiful living spaces. Trusses and framing with engineered wood are far more common and less expensive.

Roof design considerations

It’s easy to include a thick layer of insulation between the floor joists in an unconditioned attic. But if a house has a complicated roof or HVAC equipment will be installed in the attic, the attic should be unvented and conditioned. Because the roof affects the structure’s energy performance, indoor air quality, and long-term durability, its design can’t be an afterthought — at least not for a green home. Integrated design is a way to involve all trade contractors in design decisions before breaking ground. Choices to consider when designing the roof system:

How will the roof be framed? Roofs have traditionally been framed with dimensional lumber, but deep rafters and ceiling joists can be replaced with I-joists or trusses that are just as strong and use less wood. Building a roof with SIPs uses less wood and incorporates insulation into the process. Replacing sawn lumber with these engineered products can save time as well as natural resources.

How will the roof be insulated? Insulation may be in the roof, the attic floor, or even a combination of the two. The type of insulation may affect how the roof is constructed and may guide the selection of framing…

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2 Comments

  1. Craig Hassell | | #1

    Link Issues
    The link to "Attic Decisions" is not working on this page.

  2. User avater GBA Editor
    Martin Holladay | | #2

    Response to Craig Hassell
    Craig,
    Thanks for letting us know. We have a glitch, unfortunately. Working on fixing it.

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