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Roof Ventilation Details for Energy Conservation InspectAPedia®  -     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

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.

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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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INTERIORS of BUILDINGS
ACOUSTICAL SEALANTS
AGE of a BUILDING - how to determine
AIR BYPASS LEAKS
AIR LEAK DETECTION TOOLS
AIR LEAK MINIMIZATION
AIR SEALING STRATEGIES
ANIMAL ALLERGENS
ASBESTOS IDENTIFICATION IN BUILDINGS
ATTIC LEAKS, CONDENSATION & ATTIC MOLD
ATTIC VENTILATION
BASEMENT HEAT LOSS
BASEMENT LEAKS Moisture or Mold
BASEMENT WATERPROOFING
BATHROOM VENTILATION
BLOWER DOORS & AIR INFILTRATION
BRICK LINED WALLS
BUCKLED FOUNDATIONS due to INSULATION?
CATHEDRAL CEILING INSULATION
CHIMNEY INSPECTION DIAGNOSIS & REPAIR
COMBUSTION AIR for TIGHT BUILDINGS
CRAWL SPACES
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR
ENERGY SAVINGS in BUILDINGS
ENERGY SAVINGS PRIORITIES
ENERGY SAVINGS RETROFIT CASE STUDY
ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE
ENERGY SAVINGS RETROFIT OPTIONS
ENVIRONMENTAL HAZARDS
FIBERGLASS INSULATION
FIBERGLASS HAZARDS
FIBERGLASS MOLD
FIREPLACE Damage & Unsafe Hearths - Settlement
FLAT ROOF MOISTURE & CONDENSATION
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOODS IN BUILDINGS-mold
FLOORING TYPES & DEFECTS
FOUNDATION WATERPROOFING
FRAMING DETAILS for BETTER INSULATION
FRAMING DETAILS for DOUBLE WALL HOUSES
FREEZE-PROOF A BUILDING
HEAT LOSS in BUILDINGS
HEAT LOSS DETECTION TOOLS
HEAT LOSS INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
Heat Tapes: Use on Roofs for Ice
HEATING COST SAVINGS METHODS
HOUSEWRAP AIR & VAPOR BARRIERS
HUMIDITY LEVEL TARGET
ICE DAM PREVENTION
Ice Dams: Comparing Two Houses
INSULATION CHOICES
INSULATION FACT SHEET- DOE
INSULATION IDENTIFICATION GUIDE
INSULATION LOCATION for BASEMENTS
INSULATION LOCATION for CAPES, CRAWLSPACES
INSULATION for GREENHOUSE or SOLARIUM
INSULATION MATERIAL IDENTIFICATION GUIDE
INSULATION MOLD
INSULATION R-Values & Properties
INSULATION & VENTILATION INSPECTION & IMPROVEMENT
  ATTIC CONDENSATION CAUSE & CURE
  Air Bypass Leaks, Thermal Tracking
  Blocked Soffit Intake Vents
  BRICK VENEER WALL INSULATION
  CATHEDRAL CEILING INSULATION
  ENERGY SAVINGS in BUILDINGS
  ENERGY SAVINGS PRIORITIES
  ENERGY SAVINGS RETROFIT CASE STUDY
  ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE
  ENERGY SAVINGS RETROFIT OPTIONS
  FRAMING DETAILS for BETTER INSULATION
  FRAMING DETAILS for DOUBLE WALL HOUSES
  Inspect Attics for Moisture or Mold
  Inspect Basements for Moisture or Mold
  Inspect Building Exterior
  Inspect the Ridge Vent System from the Attic
  Inspect the Soffit Vent System from the Attic
  Insulation Air & Heat Leaks
  INSULATION R-Values & Properties
  Insulation Values of Log Home Walls
  POLYISOCYANURATE FOAM INSULATION
  POLYSTYRENE FOAM INSULATION
  RADIANT BARRIERS
  RIGID FOAM USE INDOORS
  Urea Formaldehyde Foam Insulation UFFI
  URETHANE FOAM Deterioration, Outgassing
  Vermiculite Insulation
LOG HOME GUIDE
MOBILE HOME INSPECTIONS
MOISTURE CONTROL in BUILDINGS
  Attic Moisture or Mold Sources
  BASEMENT HEAT LOSS
  BASEMENT LEAKS Moisture or Mold
  BASEMENT WATERPROOFING
  Chimney Leaks
  CRAWL SPACE Dryout Procedures
  DEW POINT CALCULATION for WALLS
  DEW POINT TABLE - CONDENSATION POINT GUIDE
  EFFLORESCENCE, Salts & White / Brown Deposits
  FLOOD Damage Assessment & Repairs
  FLOOD DAMAGED FOUNDATIONS
  FLOOD VENTS
  FLOODS IN BUILDINGS-priorities
  FOUNDATION WATERPROOFING
  HUMIDITY CONTROL & TARGETS INDOORS
  HOUSEWRAP AIR & VAPOR BARRIERS
  LOG HOME Leak Diagnosis & Cure
  LOG HOME Condensation &Moisture
  MOISTURE CALCULATIONS
  MOISTURE PROBLEMS: CAUSE & CURE
  MOLD in BUILDINGS
  Soffit Intake Vents & Attic Condensation
  WATER ENTRY in BUILDINGS
  VENTILATION DESIGN PROBLEMS & SOLUTIONS
  WHOLE HOUSE VENTILATION Strategies
Mold Growth Resistance of Foam Insulation
MOLD INFORMATION CENTER
ODORS & SMELLS DIAGNOSIS & CURE
PAINT FALURE, DIAGNOSIS, CURE, PREVENTION
PLASTER & BEAVERBOARD & DRYWALL
RADIANT BARRIERS
RADIANT HEAT
RADIANT HEAT Floor Mistakes to Avoid
RADIANT SLAB FLOORING CHOICES
RADIANT SLAB TUBING & FLUID CHOICES
ROOF VENTILATION SPECIFICATIONS
  Inspect the Ridge Vent System from the Attic
  Inspect the Soffit Vent System from the Attic
  Insulation Air & Heat Leaks
  Roof Venting: Intake - Outlet Area Ratios
  Roof Venting: Proper Locations
  Roof Venting: Both Ridge & Eaves Venting Needed
  Roof Venting: Eaves Intake if no Overhang
  Roof Venting: Soffit Intake Vent-Continuous
  Roof Venting: Un-Vented Roof Solutions
  ROOF VENTING ENERGY SAVING DETAILS
  ROOF VENTING NEEDED?
  Soffit Ventilation
ROT, FUNGUS, TERMITES
  TERMITE SHIELDS vs TERMITICIDE
ROT, TIMBER FRAME
SAFETY HAZARDS & INSPECTIONS
SEARS KIT HOUSES
SOLAR ENERGY SYSTEMS
  PASSIVE SOLAR DESIGN METHOD
  PASSIVE SOLAR HEAT PERFORMANCE
  PHOTOVOLTAIC POWER SYSTEMS
  SLAB INSULATION, PASSIVE SOLAR
  SOLAR COLLECTOR AIR or GAS COLLECTION
  SOLAR COLLECTOR FILMS
  SOLAR COLLECTOR WOOD HOUSINGS
  SOLAR HEATING SYSTEMS
  SOLAR HOT WATER HEATERS
  SOLAR HOUSE EVALUATION
  SWIMMING POOL SOLAR HEAT, INDOOR
SOUND CONTROL in BUILDINGS
STAIN DIAGNOSIS
STAIRS, RAILINGS, LANDINGS, RAMPS
STUCCO OVER FOAM INSULATION
STRUCTURAL INSPECTIONS & DEFECTS
SUMP PUMPS GUIDE
THERMAL EXPANSION of MATERIALS
THERMAL MASS in BUILDINGS
THERMAL MASS in UPSTAIRS
THERMAL TRACKING Indicates Heat Loss
VAPOR BARRIERS
VENTILATION in BUILDINGS
  Air Bypass Leaks, Thermal Tracking
  ATTIC CONDENSATION CAUSE & CURE
  BATHROOM VENTILATION
  Blocked Soffit Intake Vents
  BLOWER DOORS & AIR INFILTRATION
  BRICK VENEER WALL INSULATION
  CATHEDRAL CEILING INSULATION
  CRAWL SPACE VENTING & Dryout Procedures
  HEAT LOSS: How to Calculate Heat Loss in a Building
  HOUSEWRAP AIR & VAPOR BARRIERS
  HUMIDITY LEVEL TARGET
  ICE DAM PREVENTION
  Inspect Attics for Moisture or Mold
  Inspect Basements for Moisture or Mold
  Inspect Building Exterior for Moisture Problems
  Inspect the Ridge Vent System from the Attic
  Inspect the Soffit Vent System from the Attic
  Insulation Air & Heat Leaks
  MOISTURE CONTROL in BUILDINGS
  MOISTURE CALCULATIONS
  MOISTURE PROBLEMS: CAUSE & CURE
  ROOF VENTILATION SPECIFICATIONS
  ROOF VENTING ENERGY SAVING DETAILS
  Soffit Ventilation
  VENTILATION DESIGN PROBLEMS & SOLUTIONS
  WHOLE HOUSE VENTILATION Strategies
WATER ENTRY in BUILDINGS
WIND TURBINES
WINDOWS & DOORS
  SKYLIGHT LEAK DIAGNOSIS & REPAIR
  SITE BUILT DOUBLE GLAZED WINDOWS
  SLOPED GLAZING DETAILS
  VERTICAL GLAZING DETAILS
  WINDOW / DOOR ENERGY EFFICIENT, DOE
  WINDOW LEAKS INTO BASEMENT
WINTERIZE A BUILDING
WOOD Burning Heaters Fireplaces Stoves

• 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."
  
• 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.
  Excerpts with updates and annotations expanding the original Best Practices Guide text can be found in the online review and book summary at BEST CONSTRUCTION PRACTICES GUIDE and also at DECK & PORCH CONSTRUCTION, at INDOOR AIR QUALITY IMPROVEMENT GUIDE, and in other articles found at InspectAPedia.com such as HOUSEWRAP AIR & VAPOR BARRIERS, SOUND CONTROL in BUILDINGS, and other topics.
• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• 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.

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