Required Site Conditions for Infrared Building Envelope Survey
The requirements listed below are based on current industry standards, including those published by ASTM, RCI and Infraspection Institute. Compromising on any of these requirements may adversely affect the results of the Infrared Building Envelop Survey.
The Required Site Conditions may vary depending the location of the Survey (interior or exterior) and the purpose of the survey.
Survey Location: Interior of Building
Purpose of Survey: Air Filtration
Clear Line of Sight: Since an infrared imager cannot “see through” objects, a direct line-of-sight is needed for all surfaces to be surveyed. Any portions of the surfaces to be surveyed with obstructions, such as cabinets, files or furniture, cannot be surveyed.
HVAC Status: The HVAC system should be operating under normal daytime conditions. This includes operating temperature as well as pressure (neutral, negative or positive).
Minimum Daytime Temperature: Daytime high temperatures should be at least 40° F. If temperatures do not rise above this point, wet areas of the roof are likely to remain frozen and not absorb solar energy. Without solar loading, thermal images indicative of moisture are not likely to be identified.
Survey Location: Interior of Building
Purpose of Survey: Moisture Presence
Clear Line of Sight: Since an infrared imager cannot “see through” objects, a direct line-of-sight is needed for all surfaces to be surveyed. Any portions of the surfaces to be surveyed with obstructions, such as cabinets, files or furniture, cannot be surveyed.
HVAC Status: The HVAC system should be operating under normal daytime conditions. This includes operating temperature as well as pressure (neutral, negative or positive).
Recent Rain or Active Leaks: The survey should be completed when the suspect areas are actively leaking or there has been a recent rain event.
Survey Location: Exterior of Building
Purpose of Survey: Air Exfiltration
Dry Building Surfaces: The building surfaces must be dry at Sunrise. Areas that had moisture at Sunrise may not have enough solar loading to show the necessary thermal patterns.
Clear Line of Sight: Since an infrared imager cannot “see through” water or objects, a direct line-of-sight is needed for all surfaces to be surveyed. Any portions of the areas to be surveyed that are obstructed, such as the presence of trees, shrubs or snow, cannot be surveyed.
Minimum Daytime Temperature: A temperature differential of at least 18°F should exist between the inside building temperature and the outside air temperature.
Winds of less than 15 mph: During daytime hours and at the time of the Survey, winds should be less than 15 mph. In addition to being a safety issue when on the roof, stronger winds can result in a cooling effect that may cause thermal images not to be seen.
No precipitation on the day of the Survey: Moisture that falls during the day of the Survey will interrupt normal solar loading and cooling of the building surfaces. Even if evaporation results in the surfaces drying, the effects of the evaporation can interfere with the thermal images.
Survey Location: Exterior of Building
Purpose of Survey: Moisture Presence
Dry Building Surfaces: The building surfaces must be dry at Sunrise. Areas that had moisture at Sunrise may not have enough solar loading to show the necessary thermal patterns.
Recent Precipitation: If the surface to be inspected is EIFS, appreciable precipitation should be recorded within a week prior to the survey. Surfaces consisting of brick, cementitious stucco, concrete, etc. should be inspected within 48 hours of precipitation sufficient to cause building to leak.
Clear Line of Sight: Since an infrared imager cannot “see through” water or 3tcobjects, a direct line-of-sight is needed for all surfaces to be surveyed. Any portions of the areas to be surveyed that are obstructed, such as the presence of trees, shrubs or snow, cannot be surveyed.
Solar Loading: The day of the Survey should be a mostly sunny day, providing good solar loading. A general rule of thumb is if the building surface or a nearby similar surface (i.e. parking lot, street or sidewalk) is warm to the touch, sufficient solar loading has occurred.
Winds of less than 15 mph: During daytime hours and at the time of the Survey, winds should be less than 15 mph. In addition to being a safety issue when on the roof, stronger winds can result in a cooling effect that may cause thermal images not to be seen.
No precipitation on the day of the Survey: Moisture that falls during the day of the Survey will interrupt normal solar loading and cooling of the building surfaces. Even if evaporation results in the surfaces drying, the effects of the evaporation can interfere with the thermal images.
