This article lists significant building ventilation system defects, definitions, and home inspection education topics. We discuss both passive ventilation systems (such as soffit and ridge vents or turbine vents in attics) and active ventilation systems such as whole house fans, power vents, and heat exchange recovery HRV ventilation systems.
The building defects and inspection points listed in these articles also guide homeowners and home buyers to building areas that merit careful attention and often point areas of safety concern or important maintenance and repair tasks. Readers should see VENTILATION in BUILDINGS for our complete list of articles on this topic. Also see building ventilation methods at INDOOR AIR QUALITY IMPROVEMENT GUIDE. Page top sketch courtesy Carson Dunlop Associates.
Use the Search Box at the top or bottom of these pages to find in-depth information about building, energy savings, and indoor environment inspection, diagnosis and repair at this website.
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8.0 VENTILATION Inspection Requirements & Defects List
8.1 Building Ventilation Inspection Requirements & Common Defects
8.1.1 Knowledge Base for Building Ventilation System Inspections
1. Describe the function of insulation and roof and underfloor space ventilation systems in homes including controlling heat and moisture flow in the building envelope.
2. Describe the function of air barriers and vapor barriers (vapor retarder, vapor diffusion retarder)
3. Describe these common forms of insulation - loose fill, batts or blankets rigid boards, foamed-in-place
4. Describe the properties of these common insulation materials – fiberglass, cellulose, mineral wool, vermiculite and perlite, expanded polystyrene, extruded polystyrene, polyisocyanurate, polyurethane (how about urea-formaldehyde?)
5. List two common air/vapor barrier materials.
6. Describe the features of adequate installation and repair technique with respect to insulation, air vapor barrier and ventilation in floors, walls and roof systems. Distinguish between attics and cathedral ceilings or flat roofs.
7. Define the following terms:
degree-days, ventilation-unconditioned spaces, ventilation-fresh air for occupants, heat vs. temperature, british thermal unit (BTU), sensible heat, latent heat of vaporization, latent heat of fusion, conduction, radiation, convection, evaporation, thermal conductivity, thermal conductance, thermal conductor, thermal insulator, thermal resistance, air leakage, wind washing, condensation, absolute humidity, relative humidity, stack effect, neutral pressure plane, dew point temperature, vapor diffusion, drying potential, sheathing, housewrap, building paper, direct vent appliance, indoor air quality (IAQ), depressurization, heat transfer, thermal bridge, convective loop, radiant barrier, R value, perm, insulating sheathing, cold wall effect, cold floor effect.
8, Identify the codes or standards which apply to insulation and ventilation systems in your area.
8.1.2 Inspection Skills for Building Ventilation Systems
1. Describe the inspection procedure for insulation in attics, other roof spaces, walls, floors, basements and crawl spaces.
2. Identify the following common defects listed on the next page.
3. Describe the implications of each defect
4. Identify safety issues for the inspector and occupant of the house (injury due to falling through the attic, electric shock).
5. Communicate findings to client verbally and in writing, recommending corrective action when needed.
8.2 House Ventilation Systems Inspection Requirements & Defects List
8.2.1 Knowledge Base for Home Ventilation Systems Inspections
1. Describe the function and importance of house ventilation systems.
2. Describe these approaches to indoor air ventilation: exhaust, supply, balanced.
3. Describe materials and components of each of the ventilation systems.
4. Describe the features of adequate installation and repair technique for each.
5. Define the following terms with respect to indoor air ventilation:
indoor air pollutants, fresh air, air sealing, exhaust ventilation, supply ventilation, balanced ventilation, heat recovery ventilator (HRV), energy recovery ventilator (ERV), heat exchanger, air exchanger, flow measuring station, flow collar, balancing damper, condensate system, defrost system, duct insulation, air filter
6. Identify the codes or standards which apply to house ventilation systems in your area.
8.2.2 Inspection Skills for Home Ventilation Systems
1. Describe the inspection procedure for house air ventilation systems including exhaust, supply and balanced systems.
2. Identify the common defects listed on the next page.
3. Describe the implications of each defect.
4. Identify safety issues for the inspector and occupant of the house (electric shock, illness due to poor air quality, injury due to moving parts).
5. Communicate findings to client verbally and in writing, recommending corrective action as needed.
HEAT RECOVERY VENTILATOR Typical Defects List
HRV CONTROLS Typical Defects List
• Ventilation fan switch not labeled
• Ventilation fan switch not found
• HRV not interlocked with furnace fan
HRV Filters Typical Defects List
HRV DUCTS Typical Defects List
• Cold-side ducts not insulated
• Poor termination or inlet location
• Termination or inlet points not found
HRV Heat Recovery Ventilator WEATHER HOODS Typical Defects List
• Inadequate backflow prevention on exhaust (flap)
• Inadequate screening on inlet
• Missing, damaged, loose
Heat Recovery Ventilator HRV Heat Exchanger Cores Typical Defects List
VENTILATION SYSTEM DUCTS AND GRILLES, Typical Defects List
• Balancing dampers missing
• Duct vapor barrier missing, damaged or incomplete
• Exhaust grilles missing
• Flow measuring stations missing
• Poor location
• Warm-side fresh air duct not properly connected to furnace duct
Readers should see VENTILATION in BUILDINGS for our complete list of articles on this topic. Also see HOME & BUILDING INSPECTORS & INSPECTION METHODS. Use the Search Box at the top or bottom of these pages to find in-depth information about building, energy savings, and indoor environment inspection, diagnosis and repair at this website. Watch out: these inspection lists do not list all possible defects for the systems discussed, and not all home or building inspectors will examine all of the items listed here. CONTACT us to suggest corrections or additions to articles at this website.
Also see building ventilation methods at INDOOR AIR QUALITY IMPROVEMENT GUIDE.
These curriculae and building defect lists are based on smilar curriculum documents first prepared by Joe Scaduto, an ASHI member who prepared course material for Northeastern University's Building Inspection Certificate program in 1988, subsequently by DF, InspectApedia's editor, for New York University ca 1988 and later, with others, recommended to ASHI, the American Society of Home Inspectors. ASHI did not adopt this material though currently that association as well as others offer extensive HOME INSPECTOR EDUCATION material. The curriculum and lists of defects are informed by additional analysis of the process of home inspection that was developed beginning Calgary, AB for Canadian and U.S. home inspector education and certification examinations in 1997. Other early contributors to home inspection education in the U.S. and Canada include Dr. Jess Aronstein, Alan Carson, Mike Casey, Mark Cramer, John Cox, Dwight Barnett, Douglas Hansen, Rick Heyl, Larry Hoytt, Bill Merrill, Kevin O'Malley, Dennis Robitalille, Keith Peddie, Pat Porzio, Roger Robinson.
Watch out: these inspection lists do not list all possible defects for the systems discussed, and not all home or building inspectors will examine all of the items listed here. CONTACT us to suggest corrections or additions to articles at this website.
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