Roofs
The
following publications and papers deal with unvented vs. vented attics and
cathedral ceilings, ceiling vapor barriers, etc.:
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Unvented Roof
Assemblies for All Climates
April 2007, Chris Schumacher. A brief summary of the benefits of
constructing unvented roofs in any climate.
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Understanding Attic Ventilation
Revised 2006, Joseph Lstiburek. Attics or roofs can be designed and
constructed to be either vented or unvented in any hygro-thermal zone.
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Roof Design
November, 2004, Building Science Corporation. Roofs can be
designed and constructed to be either vented or unvented in any hygro-thermal
zone.
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Venting on Venting
Revised November 2004. Just about everyone in the building industry can be guilty
of using building terms loosely, and a prime example is with attics, roof
assemblies. Just so that we are all on the same page.
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Unvented Roof Summary Article
Updated February 2003. This article covers the basic theory and practice behind
unvented, cathedralized, conditioned attics; it also summarizes and
references the other articles shown below.
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Unvented Roofs,
Hot-Humid Climates, and Asphalt Shingles
January 2003, Joseph Lstiburek. If you are considering the above
combination, read this to understand the physics and the right approach to
use in construction.
- Unvented
Roof Systems
January, 2001, Joseph Lstiburek. Unvented roof systems can be safely
used in many different climates. In cold climates, insulating sheathing
must be added exterior to the roof sheathing to prevent condensation on
the underside of the roof sheathing.
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Unvented-Cathedralized Attics: Where
We've Been and Where We're Going
ACEEE Proceedings, August, 2000, Armin F. Rudd, Joseph W.
Lstiburek, Kohta Ueno. Unvented- cathedralized attics are recommended for
hot climates to decrease cooling loads. Results from test houses are
presented in detail.
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Performance
of Building America Initiative Houses with Unvented Attics and Tile Roofs
Constructed by Pulte Homes, Las Vegas Division
September, 1999, Armin Rudd. Both energy modeling and field testing reveal
no energy penalty for unvented attics in a hot climate. Differences
associated with tile versus asphalt roofing shingles are also discussed.
- Vented and Sealed
Attics in Hot Climates
June, 1997, Armin F. Rudd, Joseph W. Lstiburek. In hot climates,
vented attics can contribute to increased cooling loads and moisture
problems especially when ducts are located in the attic. Results showed
that, when compared to typically vented attics with the air distribution
ducts present, sealed "cathedralized" attics (i.e. sealed attic
with the air barrier and thermal barrier [insulation] at the sloped roof
plane) can be constructed without an associated energy penalty in hot
climates.
- Measurement of Attic Temperatures
and Cooling Energy Use In Vented and Sealed Attics In Las Vegas,
Nevada
1996, Armin F. Rudd, Joseph W. Lstiburek and Neil A. Moyer. Sealed
(unvented) attics reduce cooling costs when ducts are located in the
attic. For tile roofs the increase in temperature of the tile and roof
sheathing is acceptable when the attic is sealed.
- Ceiling Vapor Barrier Debate
1999, Joseph Lstiburek. "To hell with the experts, this is my
answer," says Joseph Lstiburek in this article that puts to rest the
age-old question regarding the use of vapor barriers, vapor retarders, and
air barriers. When coupled with "Air Barriers vs. Vapor
Barriers" above, you are all set.
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