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A Checklist for Odor Source Diagnosis InspectAPedia®  -     A Checklist helps diagnose and track down the source of building odors Does your home have "BO" - building odor? Links to articles on diagnosing and curing smells in buildings

This article provides a checklist and a methodology useful for tracking down the sources of odors in buildings.

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Checklist for Diagnosing the Source of Odors or Smells in Buildings

We offer below a list of clues that any home owner, home inspector, or other investigator can follow in seeking to pinpoint the source of an annoying or obnoxious odor in buildings. Readers are asked to contact us to suggest additions or corrections to this list.

Often people's perception of odors varies with time and exposure or with a number of other site factors that make it hard to track down just where a smell is coming from. But if we think carefully about when, and under what conditions we notice odors, often that information is instrumental in tracking down an odor to its source and thus in helping us decide if an odor refers to a potentially dangerous or unhealthy condition.

This list is in simple alphabetic order, not in order of probable cause, importance, or health risk, all of which can vary widely.

• Odors & Heating Equipment or other Appliances: does the odor appear only when certain appliances are running: cook stove, air conditioner, heater, aquarium pump, fans, clothes dryers, clothes washers, dishwashers, or electrical devices such as TV's?
  
  Heating Oil fired equipment: If the odor appears to be related to oil burning appliances such as an oil fired furnace, boiler, or water heater, see OIL HEAT ODORS. If the odor appears due to a leaky oil tank or a heating oil spill, see OIL TANK LEAK ODORS.
  
  LP or Natural Gas fired equipment: If the odor appears related to gas burning heating appliances, see chimney backdrafting, leaks, and odors from flues. Separately we discuss CARBON MONOXIDE hazards in buildings. Readers concerned with LP gas or natural gas combustion flue gas products and hazards should also see Natural Gas Combustion Products and also LP & Natural Gas Safety Hazards.
  
  Also see CHIMNEY INSPECTION & REPAIR GUIDE if odors appear related to any heating appliance that vents through a chimney.
  
  
• Odors & Building Structure: does the odor relate to presence of a nearby air movement pathway such as a building stairwell, elevator shaft, or heating and cooling duct system?
• Odors & Building height, use, occupancy: does the odor relate to the level in the building (convection currents are very powerful updrafts in high-rise buildings), to use of elevators, windows open or shut, stairwell or parking garage doors open or shut; condition of air shafts, cooking.
  
  
• Odors & Fans: while exhaust fans are often used to move odors out of a building, a little thinking and investigating may be in order: does the exhaust fan or whole house fan or attic roof vent fan cause odors, dust, or even mold to move upwards through the building? (Be careful that your whole house fan or other exhaust fans do not overpower and cause improper operation of your radon mitigation system if you have one installed).
  
  
• Odor history: when was the odor first noticed? What date? For how long has it been observed? Who first observed it? Does the first occurrence of a smell relate to an event, change, or modification in the building? If so, what exactly?
  
  
• Odor location: does the odor appear throughout a building or only on certain floors, in certain rooms, or at certain walls?
  • What is different about the room where an odor appears:
    • What side of the building is the room on? What conditions are different there such as sun exposure, wind exposure, nearby trees, prevalent wind direction, outdoor possible odor sources?
    • What side of the room, what wall, has the strongest odor: is it an exterior or interior wall?
    • What materials are unique to the odor-source room, such as carpets, carpet padding, drapes, window shades, kind and type and age of windows, screens, heat, air conditioning, pet occupancy, people occupancy, laundry storage, proximity to baths, kitchens, laundry, openings between floors?
  • What is different about the floor or level in a building where odors occur? Proximity to basements, attics, leaks, rodents, pests, animals, heating equipment, pesticide treatments
    
    See SMELL PATCH TEST to Track Down Odors where we describe a procedure that assists in pinpointing odor sources to a particular surface or piece of furniture or carpeting, using aluminum foil, paper towels, and simple masking tape.
    
    
• Odors & neighbors: does the odor correlate with activities by building occupants or building neighbors? What about trash burning, level of septic system usage, use of woodstoves, coal stoves, home improvements, building projects.
  
  
• Odors & occupants: does the odor occur when the building is occupied by large number of people, visitors, or specific individuals who may have brought something new into the building?
  
  
• Odor perceivers: who notices the smells? Is the odor perceived only by certain occupants? Is the odor more noticeable to building occupants or to occasional visitors. People's sensitivity to many odors tends to diminish over longer exposure times as the odor-sensing neurons and brain response become desensitized.
  
  Such individuals may notice an odor only upon entry to a building and not after being indoors for a time; people can also become desensitized to an odor such that even after leaving and returning to the building they do not notice the odor as much as is noticed by visitors. This seems especially true with animal and pet odors for people who live with pets.
  
  
• Odors & Pets or other Animals in Buildings: what is the history of animals and pets occupying the building? What about prior owners and their pets. What about animal pests such as rodents: mice, squirrels, raccoons, insects, who may be responsible for smelly insulation, animal urine or fecal waste on building surfaces, dead animals in walls or ceilings. See Building Inspection & Test Procedures for Pet Allergens.
  
  
• Odors & Plumbing: does the odor presence relate to the use or dis-use of plumbing fixtures in the building? Does heavy usage bring out the odor problem? Problems with the building drain-waste-vent piping, leaks, and even loose toilets are common sources of sewer gases, septic odors, and even "rotten egg" odors in buildings.
  
  Does the odor problem seem worse when the building has been unoccupied for some time? See SEWER GAS ODORS and SEWER GAS ODORS in COLD WEATHER for drain and septic system related odor diagnosis. See ODORS IN WATER for smells in drinking water or showers.
  
  
• Odor strength: is the odor perceived as strong or mild?
  
  
• Odors & time of occurrence: does the odor appear all of the time or only at certain times. For odors that come and go, does the time of the odor correlate with:
  • Time of day, sunlight, operation of heating or cooling equipment
  • Time of year, season, foliage, outdoor or indoor activities including activities of neighbors or industrial facilities that can produce odors, chemicals, gases, that move towards the subject property
  • Heating or cooling season: does the odor appear when the heating system comes on? Check immediately to assure that there are no carbon monoxide hazards or flue gas hazards. See CARBON MONOXIDE & GAS HEAT ODORS
  • Cooking activities may be an odor source
  • Odors in high-rise buildings: use of elevators, use of stairwells, doorways left open or shut during different periods
• Odors & local temperature: does the odor appear or disappear in relation to changes in building temperature?
  • Sunlight striking plastic window screens may make a distinctive odor only on the sunlit side of the building
  • Plumbing system drains or vent systems may release odors when a private septic system is under heavy use or in certain weather conditions - see SEWER GAS ODORS in COLD WEATHER;
    
    
• Odors & weather conditions: does the odor correlate with weather conditions such as humidity, temperature, rain, snow, wind?

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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.

ENVIRONMENTAL HAZARDS GUIDE
MOLD INFORMATION CENTER
ODORS, Smells, Gases in Buildings-Diagnosis & Cure
ANIMAL ODORS IN BUILDINGS
CARBON MONOXIDE & GAS HEAT ODORS
CARPETS & PADDING ODORS IN BUILDINGS
GAS MEASUREMENT TOOLS
HEATING OIL EXPOSURE HAZARDS, LIMITS
HEATING SYSTEM ODORS
HOUSEWRAP AIR & VAPOR BARRIERS
MOLD ODORS, Musty Smells in Buildings
ODOR DIAGNOSIS CHECKLIST
ODORS, SEPTIC or SEWER
ODORS IN WATER
OIL HEAT ODORS
OIL TANK LEAK ODORS
OZONE for MOLD OR ODORS
SMELL PATCH TEST to Track Down Odors
PAINTS & COATINGS ODORS IN BUILDINGS
PLASTIC ODORS-SCREENS, SIDING
PLUMBING SYSTEM ODORS
SEPTIC SYSTEM ODORS
SEWER GAS ODORS
SEWER GAS ODORS in COLD WEATHER
VINYL Siding or PLASTIC Window ODORS in Buildings
VINYL CHLORIDE HEALTH INFO
WATER ODORS

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