Professionalism and TrustMy Account Apply for Membership My Account Apply for Membership National Association of Infrared Specialists 16192 Coastal Highway, Lewes, Delaware 19958 NAIS Building Envelope Standards of Practice (EnvelopeSOP) This standard sets the requirements for infrared surveys of building envelopes: insulation, air leakage and moisture in walls, ceilings, floors and foundations. Section 1: Purpose, Scope and Alignment 1.1 Purpose. To set a uniform, defensible minimum standard for infrared surveys of building envelopes of residential and commercial buildings. 1.2 Alignment with NAIS Core Standards. This standard is an addendum to the NAIS Core Standards of Practice (CoreSOP) and the NAIS Code of Ethics. Everything in the CoreSOP applies unless this standard says otherwise. It is based on ASTM C1060 (insulation in frame buildings), ASTM E1186 (air leakage site detection) and ISO 6781 (thermal irregularities in building envelopes). 1.3 Scope. Non-invasive thermographic evaluation of readily accessible envelope surfaces to detect insulation anomalies, thermal bridges, air leakage paths and suspected moisture. 1.4 Exclusions. This standard does not cover roof membranes (see the Roofing standard), structural evaluation, code compliance, identification of mold or other microbial growth, or energy modeling. Section 2: Definitions Term Meaning Building envelope The parts of a building that separate the conditioned interior from the outside: walls, roof assembly, floors, foundation, windows and doors. Thermal bridge A conductive path through an assembly that carries heat faster than the surrounding insulation. Thermal bypass Uncontrolled air movement through or around a thermal barrier. Blower door A fan mounted in a doorway that pressurizes or depressurizes the building to reveal air leakage. Readily accessible Reachable for imaging without moving personal property, removing finishes or taking unsafe actions. Section 3: Required Conditions Survey type Condition Requirement Qualitative insulation survey Surface-to-surface delta-T At least 10 degrees C (18 degrees F) surface to surface, held for at least 4 hours before the survey Air leakage with blower door Delta-T during pressurization or depressurization At least 1.7 degrees C (3 degrees F) Exterior scan, frame construction Solar history No direct sun on the surface for at least 3 hours before Exterior scan, masonry veneer Solar history No direct sun on the surface for at least 8 hours before Exterior scan Wind speed No more than 8 mph (12.8 km/h) Exterior scan Rain and wet surfaces None during the survey; surfaces dry unless wetness is the subject If a condition cannot be met, the thermographer shall either reschedule or record the departure and its effect on the result (CoreSOP Section 9.2). Section 4: Procedure 4.1 Order. Survey the interior where possible, because it avoids solar and wind effects. Survey the exterior as well when the purpose needs it. 4.2 Preparation. The thermographer should ask that furniture be moved from exterior walls and that heating or cooling run normally for the preceding period. 4.3 Imaging. Image each area from a consistent distance and angle. Take an overview of every elevation or room, then close-ups of anomalies. 4.4 Comparison. Compare each anomaly with a nearby area of the same construction. A difference between different assemblies is not an anomaly. 4.5 Location. Record the location of every anomaly on a plan or in a numbered photo log. Section 5: Insulation Anomalies that suggest missing, compressed or displaced insulation shall be described as a likely cause only, not a confirmed one. Framing members, fasteners and other thermal bridges are expected patterns. Report them only where they are abnormal for the design. Where possible the finding should be confirmed with a borescope or a small inspection opening, with the owner's permission. Section 6: Air Leakage Air leakage surveys should be done with the building under a pressure difference, such as a blower door test, as ASTM E1186 describes. The thermographer shall record the pressure difference and the delta-T, and note which areas were not pressurized. Leakage paths that the imager alone cannot locate shall be described as suspected. Section 7: Moisture Thermal anomalies that suggest moisture shall be verified with a moisture meter or other secondary tool. Pin and pinless meters measure different things, and the report shall say which was used. The thermographer shall not state that mold, rot or structural damage is present. Where moisture is found, the report should recommend that a qualified person investigate its cause and extent. Moisture readings shall be recorded with the material, the location and the meter reading, and compared with a dry reference reading of the same material. Section 8: Reporting The report shall meet CoreSOP Section 7, with the following added: a plan or photo log locating every anomaly; the indoor and outdoor air temperatures and the surface delta-T at the time of the survey; and, for air leakage, the pressure difference used. Section 9: Limitations This survey is limited to readily accessible surfaces and to the conditions at the time of the survey. It does not see inside closed cavities, cannot identify mold or microbial growth, and cannot by itself determine the cause of a pattern. The CoreSOP limitations statement shall appear in every report.

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