Attic Ventilation Design Strategies for Manufactured
Homes (October 2002, 42 p.)
A literature search and review was conducted to investigate
attic ventilation design strategies for manufactured homes.
The findings of the literature review were debated among,
and analyzed by, a Steering Committee of industry representatives.
The literature reveals that ventilation of attic and cathedral
ceiling air cavities have been recommended building practices
for four reasons: moisture control, energy conservation, asphalt
shingle durability, and ice dam prevention. U.S. building
codes, including the HUD-code, require attic ventilation in
most cases for all climates. The practice of ventilating all
attics is based on research conducted in cold climates. Studies
in other areas suggest that optimal attic system design may
vary significantly by climate.
The research concluded that homes in the hot, humid climate
may benefit the most from alternate attic design strategies,
including an unvented attic design. A program of testing is
proposed to evaluate various attic design strategies including
an unvented attic constructed simply by eliminating the ventilation
openings, a sealed attic constructed by intentionally sealing
the roof cavity, an attic with insulation in the roof plane,
and a conventionally constructed vented attic. The end product
of this proposed work would be one or more attic designs for
hot, humid climates with improved moisture control performance
characteristics.
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