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This website discusses how to inspect, diagnose ventilation problems in buildings and suggests building ventilation methods. 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 photo shows an area of melted snow on this New York cape cod home, indicating an area where escaping heat has led to a warm roof area, building heat loss, and possibly leaks into the building interior.

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.

© Copyright 2010 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Key Articles about Building Ventilation Design, Inspection, Diagnosis, Cure

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.

• Air Bypass Leaks, Thermal Tracking indoor stains can indicate air leaks and insulation or vapor barrier defects
• ATTIC CONDENSATION CAUSE & CURE - how to get rid of or prevent excessive attic moisture, condensation, and related mold problems
• BATHROOM VENTILATION - effective bath ventilation avoids attic and other building moisture problems
• Blocked Soffit Intake Vents - roof intake venting design
• CATHEDRAL CEILING INSULATION - alternatives for avoiding moisture problems in cathedral ceilings
• CRAWL SPACE VENTING & Dryout Procedures - what to do about a damp or wet crawl space
• Heat Tapes: Use on Roofs for Ice - a stopgap measure to avoid ice dam leaks
• INDOOR AIR QUALITY IMPROVEMENT GUIDE - extensive guide to selection and design of indoor air quality problem solutions
• Inspect Attics for Moisture or Mold - how to spot signs of moisture & ventilation trouble in attics
• Inspect Basements for Moisture or Mold - how to spot signs of moisture & ventilation trouble in basements
• Inspect Building Exterior for Moisture Problems - how to spot signs of moisture & ventilation trouble on the building exterior
• Inspect the Ridge Vent System from the Attic - how to spot signs of moisture & ventilation trouble in attics
• Inspect the Soffit Vent System from the Attic - how to spot signs of moisture & ventilation trouble in attics
• BLOWER DOORS & AIR INFILTRATION - how we test a building for air leaks
• HEAT LOSS: How to Calculate Heat Loss in a Building - what will it cost to heat the building, where are the problems
• HOUSEWRAP AIR & VAPOR BARRIERS - to avoid air leaks and moisture troubles
• HUMIDITY LEVEL TARGET - how dry does the building interior need to be
• ICE DAM PREVENTION - what are ice dams, what causes them, why do they cause building leaks & mold
• MOISTURE CONTROL in BUILDINGS - guide to indoor building moisture theory & design
• "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.
• Crawl Space Ventilation - how to ventilate or not ventilate a crawl space, and why
• MOISTURE PROBLEMS: CAUSE & CURE - guide to building moisture
• Roof Ventilation - design guide for proper roof ventilation
• Roof Venting: Intake - Outlet Area Ratios
• Roof Venting: Proper Locations
• Roof Venting: Both Ridge & Eaves Venting Needed
• Roof Venting: Soffit Intake Vent-Continuous
• ROT, TIMBER FRAME - how moisture, vapor barrier, & insulation may conspire to rot a building
• Soffit Ventilation - design guide for proper soffit ventilation at the building roof eaves
  
• HOUSEWRAP AIR & VAPOR BARRIERS
• WHOLE HOUSE VENTILATION Strategies, in depth article on building ventilatin concepts, designs, products, including Guide to Sizing House Ventilation, Whole House Ventilation Table, Installation of Whole House Ventilation, Exhaust-Only Ventilation, Single-Port Exhaust Venting,, Multiport Exhaust Venting, Ventilating Heat-Pump Systems,, Supply-Only Ventilation, Forced-Air Supply Ventilation and Multiport Supply Ventilation

Other Articles Related to Building Ventilation, Insulation, Moisture, Air Leaks, Heating Cost

• ATTIC CONDENSATION CAUSE & CURE and Ice Dam Leaks - Detection and Correcting Venting and Condensation Problems in Buildings
• Building water entry: what the basement waterproofing companies don't tell you? Water entry prevention and repair suggestions.
• BLOWER DOORS & AIR INFILTRATION - how to measure air leaks, equivalent leakage area (ELA), and air changes per hour (ACH) in a building
• Brick Lined Wall Cavities in Wood Framed Homes - Brick Nogging and What it Means to a Home Buyer or Home Owner
• Carpet Mold Inspection how to look for mold in carpets
• Carpet Mold Test Guide suggestions for alternative methods to test carpeting for mold
• Ceilings: see How to recognize ceiling tiles that may contain asbestos
• Chimneys fire hazards, heating flues, woodstoves, coal stoves, & fireplaces: chimney inspection, defects, safety concerns, repair methods
• Environmental hazards: allergens, EMF, lead paint, lead in water, leaks, moisture, venting, mold-contamination, MVOCs, radon, toxic gases
• Fiberglass Building insulation: are fiberglass particles a problem in indoor air? Is fiberglass insulation a mold harbor
• FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP A Guide to Mold Cleanup Procedures
• Floods in Buildings & interior water damage cleanup, prevention, testing quick steps to prevent mold contamination
• Flooring 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
• INSULATION IDENTIFICATION GUIDE - how to identify various building insulation products
• INSULATION INSPECTION & IMPROVEMENT: Insulation in Buildings: Identification, R-values, Heat loss, Insulation Types, Insulation Characteristics
• 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
• Mold Prevention: Avoiding Mold Problems in Buildings by Using Mold-resistant Construction Products & Practices
• ODORS & SMELLS DIAGNOSIS & CURE - how to identify and remove all kinds of odors in buildings
• Rot, fungus, termites, carpenter ants, powder post beetles, & other wood destroying organisms
• SHEATHING, FOIL FACED - VENTS - do we need to vent building walls with siding installed over foam board insulating sheathing?
• Stain Diagnosis on Indoor Surfaces, how to diagnose stains on walls, floors, carpets, and how to determine the stain source
• 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
• VAPOR BARRIERS & CONDENSATION in BUILDINGS
• VAPOR CONDENSATION & BUILDING SHEATHING
• VAPOR BARRIERS & HOUSEWRAP
• VENTILATION in BUILDINGS - extensive guide to selection & design of building ventilation systems
  •   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: 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
      VENTILATION DESIGN PROBLEMS & SOLUTIONS
      WHOLE HOUSE VENTILATION Strategies
• 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
• 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.

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Technical Reviewers & References

• InspectAPedia.com^® - Daniel Friedman
• InspectAPedia Bookstore lists recommended books, organized by topic & available for purchase. Most of our articles also include a list of recommended books for the specific article topic as well as other references, and information sources.
• Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
• Additional technical contributors & reference sources for this article are listed below.

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

HOUSEWRAP AIR & VAPOR BARRIERS
HUMIDITY LEVEL TARGET

VAPOR BARRIERS & AIR SEALING at BAND JOISTS
VAPOR BARRIERS & HOUSEWRAP
VAPOR CONDENSATION & BUILDING SHEATHING

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
  ROOF VENTING NEEDED?
  Soffit Ventilation
  VENTILATION DESIGN PROBLEMS & SOLUTIONS
  WHOLE HOUSE VENTILATION Strategies

• "Minimizing Air Leakage in Log Homes"
• "Controlling Moisture in Log Homes" and the more general (but brief) DOE article series on moisture control:
  • "Moisture Control", U.S. DOE
  • "Moisture Control in Basements", U.S. DOE
  • "Crawl Space Moisture Control", U.S. DOE
  • "Slab-on-Grade Foundation Moisture and Air Leakage Control", U.S. DOE
  • "Moisture Control in Walls", U.S. DOE
• "Ventilation", U.S. DOE, describes the purpose of building ventilation and three basic ventilation strategies:
  • Natural house ventilation methods
  • Whole House Ventilation Methods, including exhaust ventilation methods, supply ventilation of buildings, balanced building ventilation, and energy recovery (heat exchanger) ventilation systems
  • Spot Ventilation in Buildings
• "Weather-Resistive Barriers", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
• "Vapor Barriers or Vapor Diffusion Retarders", U.S. DOE: how vapor barriers work, types of vapor diffusion barriers, installing vapor barriers

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

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• 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
  • 1993 ASHRAE Handbook Fundamentals (Hardcover), ISBN-10: 0910110964 or ISBN-13: 978-0910110969
• The National Institute of Standards and Technology, NIST (nee National Bureau of Standards NBS) is a US government agency - see www.nist.gov
  • "A Parametric Study of Wall Moisture Contents Using a Revised Variable Indoor Relative Humidity Version of the "Moist" Transient Heat and Moisture Transfer Model", George Tsongas, Doug Burch, Carolyn Roos, Malcom Cunningham; this paper describes software and the prediction of wall moisture contents. - PDF Document from NIS
• Understanding Ventilation: How to Design, Select, and Install Residential Ventilation Systems, John Bower
• Linric psychrometric tools can be found at www.linric.com
• "Weather-Resistive Barriers", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
• ...

More Information on Building Diagnostic Inspections and Repairs

• Links to our list of additional information sources: Interior Defects in Buildings

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