Indoor air quality and building ventilation specifications
Questions & answers about building ventilation diagnosis, improvement, repair, inspection, standards & specifications
Building ventilation diagnosis, improvement, repair, inspection, standards & specifications: these articles explain how to inspect, diagnose and repair ventilation problems in buildings. We suggest building ventilation methods and we describe the pros and cons of different ventilation approaches used to assure good indoor air quality, low building energy usage, and minimal building moisture problems.
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Key Articles about Building Ventilation Design, Inspection, Diagnosis, Cure
Information is provided about visual clues of building condition as well as direct inspection for the presence or absence of proper building ventilation systems, pathways, and moisture and air barriers to stop leaks where we do not want ventilation.
Our page top sketch explaining the wind-washing effect on attic insulation is provided courtesy of Carson Dunlop Associates. At left we show an example of severe indoor condensation at a window.
We discuss how to identify and correct various building leaks, moisture, and venting
problems such as ice dams, blocked attic ventilation, excessive indoor humidity, how to prevent indoor mold, and how to respond to building floods and
similar emergencies.
Our photo (left) shows extreme condensation at a building basement window. Moisture at this level risks severe mold growth which can be costly to clean up, and over a longer time this condition invites rot or insect attack on the building. Below is our list of articles on the diagnosis and cure of building ventilation problems.
"Moisture Problems: Causes and Cures. Understanding moisture problems can steer you free of trouble", Steve Bliss: Building it Right, Solar Age, March 1983 p. 37, 38. -- Adapted with permission, from original material to form this web page article.
VENTILATION, BALANCED HEAT COST SAVINGS - how to calculate heating cost savings from correcting the building air change rate and using balanced ventilation systems
FLOOR TYPES & DEFECTS - inspection, diagnosis, repair, and installation tips for resilient flooring, vinyl and asphalt floor tiles, wood flooring, tile floors, carpeting in buildings
Heat Loss in buildings, how to determine and calculate heat loss from a building (or heat gain in a cooling climate), how to evaluate building insulation, & how to insulate buildings
Humidity: How Low Should You Keep Indoor Humidity to Avoid a Mold Problem
Ice Dam Leaks in building attics and roof cavities, how to inspect for evidence of leaks, identify causes, and correct bad attic ventilation, improper roof venting, and these causes of attic mold or roof structure damage
MOISTURE CONTROL in buildings - home page of our extensive list of articles on how to identify and fix sources of building water or moisture problems
Mold Prevention: Avoiding Mold Problems in buildings by Using Mold-resistant Construction Products & Practices
Thermal Tracking & Stains how to recognize thermal tracking or thermal bridging & how to diagnose Stains on Ceilings & Walls, Building Air Leaks & Insulation Defects, as well as other indoor air quality or building concerns
VENTILATION in buildings - home page for our extensive list of articles on how to properly ventilate buildings
VENTILATION DESIGN PROBLEMS & SOLUTIONS - describes common design issues in making a successful building ventilation system, providing solutions for various building venting and moisture problems with supply air & return air problems & solutions, Building indoor air pressure drop during ventilation, Building indoor air ventilation system noise problems & solutions, and building Ventilation airflow controls
WIND WASHING INSULATION At EAVES - how wind and air movement in to a building at soffit vents can push back insulation and lead to heat loss in buildings, ice dams, and even leaks into building walls.
WINTERIZE A BUILDING - how to protect a building and its plumbing and mechanical systems from freeze damage, how to shut down a building to minimize damage; how to de-winterize a building.
Frequently Asked Questions about proper building ventilation methods, curing ventilation, moisture, or fresh air problems in buildings, and venting tricky or difficult building designs
Question: How to fix "Leaks" or condensation problem in roof at un-vented valley rafters?
I just built a new house consisting of cathedral ceilings throughout. I installed perforated soffits along the bottom of the eaves, however, I mistakenly forgot to vent the roof along the valley rafters spanning approximately 30' in length. I have discovered a leak at both valley only occuring in the spring time when the temperature finally rises above freezing.
I strip back both valleys and re shingled using snow and ice shield as well as torch down roofing, it still leaked at first snow. Is my roof sweating from improper ventilation? I also ran the ridge vent continuously along the peak, should I only have this where the soffit is vented?(not above the valley). I ran styrofoam baffles under all of the sheathing even at the valley rafter, could this be warming the roof where they are not vented to the soffit? Can somebody offer some helpful advice? - Scott
Reply:
Scott, the ice and water shield approach can stop leaks around valleys - and is a good practice. The fact that you observed leaks when temperature rises above freezing suggests that a pile-up of snow or ice in the roof valleys is melting, that the water load is exceeding the present roof valley's ability to drain without leakage, and that thus water is finding its way under the shingles past the valley and into the building.
Waterproofing three feet on either side of most valleys will seem to "fix" this leak, but we really don't want to leave water trapped under the roof shingles either - that can be a source of roof damage and reduced roof life.
So in addition to the ice and water shield membrane improvement, take a look at roof valley design details including bends and sealants that prevent water from passing out of the valley and into the roof structure.
These three articles should be helpful in curing leaks at your roof valleys for all weather conditions:
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"Weather-Resistive Barriers [copy on file as /interiors/Weather_Resistant_Barriers_DOE.pdf ] - ", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
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, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book 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. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
ASHRAE resource on dew point and wall condensation - see the ASHRAE Fundamentals Handbook, available in many libraries. The following three ASHRAE Handbooks are also available at the InspectAPedia bookstore in the third page of our Insulate-Ventilate section:
2005 ASHRAE Handbook : Fundamentals : Inch-Pound Edition (2005 ASHRAE HANDBOOK : Fundamentals : I-P Edition) (Hardcover), Thomas H. Kuehn (Contributor), R. J. Couvillion (Contributor), John W. Coleman (Contributor), Narasipur Suryanarayana (Contributor), Zahid Ayub (Contributor), Robert Parsons (Author), ISBN-10: 1931862702 or ISBN-13: 978-1931862707
2004 ASHRAE Handbook : Heating, Ventilating, and Air-Conditioning: Systems and Equipment : Inch-Pound Edition (2004 ASHRAE Handbook : HVAC Systems and Equipment : I-P Edition) (Hardcover)
by American Society of Heating, ISBN-10: 1931862478 or ISBN-13: 978-1931862479
"2004 ASHRAE Handbook - HVAC Systems and Equipment The 2004 ASHRAE HandbookHVAC Systems and Equipment discusses various common systems and the equipment (components or assemblies) that comprise them, and describes features and differences. This information helps system designers and operators in selecting and using equipment. Major sections include Air-Conditioning and Heating Systems (chapters on system analysis and selection, air distribution, in-room terminal systems, centralized and decentralized systems, heat pumps, panel heating and cooling, cogeneration and engine-driven systems, heat recovery, steam and hydronic systems, district systems, small forced-air systems, infrared radiant heating, and water heating); Air-Handling Equipment (chapters on duct construction, air distribution, fans, coils, evaporative air-coolers, humidifiers, mechanical and desiccant dehumidification, air cleaners, industrial gas cleaning and air pollution control); Heating Equipment (chapters on automatic fuel-burning equipment, boilers, furnaces, in-space heaters, chimneys and flue vent systems, unit heaters, makeup air units, radiators, and solar equipment); General Components (chapters on compressors, condensers, cooling towers, liquid coolers, liquid-chilling systems, centrifugal pumps, motors and drives, pipes and fittings, valves, heat exchangers, and energy recovery equipment); and Unitary Equipment (chapters on air conditioners and heat pumps, room air conditioners and packaged terminal equipment, and a new chapter on mechanical dehumidifiers and heat pipes)."
1996 Ashrae Handbook Heating, Ventilating, and Air-Conditioning Systems and Equipment: Inch-Pound Edition (Hardcover), ISBN-10: 1883413346 or ISBN-13: 978-1883413347 ,
"The 1996 HVAC Systems and Equipment Handbook is the result of ASHRAE's continuing effort to update, expand and reorganize the Handbook Series. Over a third of the book has been revised and augmented with new chapters on hydronic heating and cooling systems design; fans; unit ventilator; unit heaters; and makeup air units. Extensive changes have been added to chapters on panel heating and cooling; cogeneration systems and engine and turbine drives; applied heat pump and heat recovery systems; humidifiers; desiccant dehumidification and pressure drying equipment, air-heating coils; chimney, gas vent, fireplace systems; cooling towers; centrifugal pumps; and air-to-air energy recovery. Separate I-P and SI editions."
Principles of Heating, Ventilating, And Air Conditioning: A textbook with Design Data Based on 2005 AShrae Handbook - Fundamentals (Hardcover), Harry J., Jr. Sauer (Author), Ronald H. Howell, ISBN-10: 1931862923 or ISBN-13: 978-1931862929
Energy Savers: Whole House Systems Approach to Energy Efficient Home Design [copy on file as /interiors/Whole_House_Energy_Efficiency_DOE.pdf ] - U.S. Department of Energy
"Energy Savers: Whole-House Supply Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Supply_Vent.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11880?print
"Energy Savers: Whole-House Exhaust Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Exhaust.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11870
"Energy Savers: Ventilation [copy on file as /interiors/Energy_Savers_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Natural Ventilation [copy on file as /interiors/Energy_Savers_Natural_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Energy Recovery Ventilation Systems [copy on file as /interiors/Energy_Savers_Energy_Recovery_Venting.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11900
"Energy Savers: Detecting Air Leaks [copy on file as /interiors/Energy_Savers_Detect_Air_Leaks.pdf ] - ", U.S. Department of Energy
"Energy Savers: Air Sealing [copy on file as /interiors/Energy_Savers_Air_Sealing_1.pdf ] - ", U.S. Department of Energy
Ice Dam Leaks in building attics and roof cavities, how to inspect for evidence of leaks, identify causes, and correct bad attic ventilation, improper roof venting, and these causes of attic mold or roof structure damage
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FLOOR TYPES & DEFECTS
