Roof venting details save on energy cost (C) Daniel Friedman

Roof Ventilation Details for Energy Conservation

Roof framing options and construction details that permit optimum roof ventilation to also conserve energy, reducing cooling & heating costs
- Roof ice dam leaks can be cured or avoided by these roof and attic venting details
Solar Age Magazine Articles on Renewable Energy, Energy Savings, Construction Practices
Questions & answers about the relationship between roof ventilation & building energy costs
References

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This article discusses saving energy by roof framing options and construction details that permit optimum roof ventilation to also conserve energy, reducing cooling & heating costs. Sketch at page top and accompanying text are reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Article on Roof Structural Details to Prevent Ice Dams while Saving Energy Costs

"Detailing for Roof Ventilation, the insulated roof requires a few adjustments in detailing - all the changes for the better" - links to the original article in PDF form immediately below are followed by an expanded/updated online version of this article.

Roof Ventilation Details - PDF form, use your browser's back button to return to this page
Roof Ventilation Details - part 2
Roof Ventilation Details - part 3

Provide Adequate Roof Cavity Space for Lots of Ventilation and Lots of Insulation

This roof ventilation design details article from Steven Bliss's "Building it Right" column in Solar Age Magazine and available in the three links just above, describes a few adjustments for insulated roofs that will assure good ventilation without wasting building heating or cooling energy. The author explains the basics of ice dams and ice dam leaks on buildings, the need for a 1- to 2-inch air space over the outer wall top plate, and the importance of continuing the air ventilation pathway up under the roof to the ridge outlet. At the same time, good roof ventilation design prevents leaks from wind, rain, insects, and rodents.

Good attic or under-roof ventilation and insulation design is described for truss roofs as well as framing tips to save time and construction costs. The "raised-heel" or Arkansas truss design is explained - a method for obtaining additional insulation over the top plate for buildings constructed in cold climates. For cathedral ceilings the author recommends flat trusses to provide adequate ceiling depth to permit both good insulation and good air ventilation in the structure.

Use Roof Vents and Roof Eaves Baffles to Assure Air Inflow for Roof Ventilation

The writer explains the use of vertical blocking or baffles to provide airflow passage between each pair of rafters or roof trusses. Where blown-in insulation is to be installed, the baffles need to continue all of the way up to the ridge outlet vent. Baffles may be site constructed using hardboard or manufactured rigid roof baffle products. Raised heel or flat truss design roofs include a vertical baffle flush with the side wall sheathing, or building wall sheathing can be continued vertically to form the baffle.

Additional Roof Venting & Gutter Details to Prevent Leaks and Rot at Roof Eaves

The writer, an advocate of the fully-vented cold-roof building design (to prevent ice dams, attic or roof condensation, and related rot or mold problems as well as providing a cooler building in hot weather) reviews gutter hanging details to assure that leaks do not occur at the vented roof eaves such as using strap hangers to keep gutters away from the fascia board, and placing the gutters low enough in snow-regions that the gutters won't be knocked off of the building by sliding snow and ice.

Options to provide intake venting at the overhang or soffit at the roof eaves include locating a continuous vent strip at the outermost edge of the overhang to minimize wind-blown rain entering the soffit from below. The author cites model building codes on the amount of net free roof vent area in the attic: 1/300 of the ceiling area if the ceiling has a vapor barrier, and 1/150 of the ceiling area if no vapor barrier is installed. We agree with the article's conclusion that these code specifications were written long ago when houses were more drafty, and when the prime concern was winter condensation risks. Because of the increased use of air conditioning in buildings even in northern climates, summer energy costs have become a concern also suggesting that more ventilation than these minimums is recommended today. Finally, if a whole house fan is to be installed blowing into the roof space or attic, still larger ventilation areas will be needed for the fan to work effectively (and to avoid a fire risk).

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Solar Age Magazine was the official publication of the American Solar Energy Society. The contemporary solar energy magazine associated with the Society is Solar Today. "Established in 1954, the nonprofit American Solar Energy Society (ASES) is the nation's leading association of solar professionals & advocates. Our mission is to inspire an era of energy innovation and speed the transition to a sustainable energy economy. We advance education, research and policy. Leading for more than 50 years. ASES leads national efforts to increase the use of solar energy, energy efficiency and other sustainable technologies in the U.S. We publish the award-winning SOLAR TODAY magazine, organize and present the ASES National Solar Conference and lead the ASES National Solar Tour – the largest grassroots solar event in the world."
Steve Bliss's Building Advisor at buildingadvisor.com helps homeowners & contractors plan & complete successful building & remodeling projects: buying land, site work, building design, cost estimating, materials & components, & project management through complete construction. Email: info@buildingadvisor.com
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: johncranor@verizon.net
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
- Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
- Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
- Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
  Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference Book, a reference & inspection report product for building owners & inspectors.
  Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & Android smart phones.
  Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter inspectaehrb in the order payment page "Promo/Redemption" space.
- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
  Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
- The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
Passive Solar Design Handbook Volume I, the Passive Solar Handbook Introduction to Passive Solar Concepts, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v1.pdf
Passive Solar Design Handbook Volume II, the Passive Solar Handbook Comprehensive Planning Guide, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v2.pdf [This is a large PDF file that can take a while to load]
Passive Solar Handbook Volume III, the Passive Solar Handbook Programming Guide, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v3.pdf
The Passive Solar Design and Construction Handbook, Steven Winter Associates (Author), Michael J. Crosbie (Editor), Wiley & Sons, ISBN 978-047118382 or 0471183083 is available at Amazon.com and via the The Passive Solar Design and Construction Handbook, Steven Winter Associates (Author), Michael J. Crosbie (Editor), Wiley & Sons, ISBN 978-047118382 or 0471183083 is available at Amazon.com and via the InspectAPedia Bookstore
"Passive Solar Home Design", U.S. Department of Energy, describes using a home's windows, walls, and floors to collect and store solar energy for winter heating and also rejecting solar heat in warm weather.
"Solar Water Heaters", U.S. Department of Energy article on solar domestic water heaters to generate domestic hot water in buildings, explains how solar water heaters work. Solar heat for swimming pools is also discussed.
"Heat Exchangers for Solar Water Heating Systems", U.S. DOE describes the types of solar water heater heat exchange methods between the sun and the building's hot water supply
"Heat-Transfer Fluids for Solar Water Heating Systems", U.S. DOE, describes the types of fluids selected to transfer heat between the solar collector and the hot water in storage tanks in a building. These include air, water, water with glycol antifreeze mixtures (needed when using solar hot water systems in freezing climates), hydrocarbon oils, and refrigerants or silicones for heat transfer.
"Solar Water Heating System Maintenance and Repair", U.S. DOE
"Solar Water Heating System Freeze Protection", U.S. DOE,using antifreeze mixture in solar water heaters (or other freeze-resistant heat transfer fluids), as well as piping to permit draining the solar collector and piping system.
"Scaling and Corrosion in Solar Water Heating Systems", U.S. DOE
www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12850 is the base U.S. DOE website for these articles
"Active Solar Heating Systems", U.S. Department of Energy, including
"Radiant Heating Systems" U.S. DOE
"Absorption Heat Pumps & Coolers", U.S. DOE
"Solar Air Heating" U.S. DOE also referred to as "Ventilation Preheating" in which solar systems use air for absorbing and transferring solar energy or heat to a building
"Solar Liquid Heating" U.S. DOE, systems using liquid (typically water) in flat plate solar collectors to collect solar energy in the form of heat for transfer into a building for space heating or hot water heating. The term "solar liquid" is used for accuracy, rather than "solar water" because the water may contain an antifreeze or other chemicals.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

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