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Thermal Inspection

We use thermal drones to detect moisture entrapment in flat commercial roofs (membrane/TPO) for property managers in Southern NH.

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Thermal inspections can be helpful on roofs (for water ingress...), solar panels (detection of blocking diodes going bad, reverse polarity, cell defects, junction or combiner box issues ...), wind turbines (connection points, switches, brushings, transformers, generators, motors, blade stress fractures...), house inspections (thermal quality, air leaks...) etc.

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All IR imagery includes a RGB image, since shadows, leaves, dirt etc can impact the results.  Being able to compare the two images helps to eliminate false positives.

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The roof below is over 20 years old.  The darker areas are cooler and should be inspected for water ingress. If it were closer to sunset, these same areas can be warmer, since water will retain heat longer than the sourrounding material.

Thermal roof inspection
Roof Inspection

This house was built in the 1800's and short on insulation.  The wood burning stove is running (patio level at chimney), with some solar noise on a 40F day, late afternoon from the left (West).  Top floor is not heated (except of heat going up stairs).  A report would include temperature area/spot annotaions indicating temperatures.  Sample report further down.

Weather on Oct 10, 2022   https://www.wunderground.com/history/daily/us/vt/south-burlington/KBTV/date/2022-10-10

Thermal house inspection: IR
Thermal house inspection: RGB

Here's a friends log cabin with extensive insulation Basement included, heated).  There isn't any detectable heat loss (40F, late afternoon).  The majority of heat detected is from solar noise.

Thermal house inspection: IR
Thermal house inspection: RGB
House Inspection : Thermal
House Inspection : RGB

Old house in Nashua with significant heat loss (54F area).  Owner insulated afterwards.

Partial example of a thermal evaluation report. 

Roof Thermal Inspection Report
House Inspection : Thermal
House Inspection : Thermal
House Inspection : Thermal

When We Fly: The Science of Optimal Conditions

1. Exterior Walls (Building Envelope)

Focus: Detecting heat loss, insulation voids, and air leakage.

  • Significant Temperature Split (Delta T)

    • Requirement: A difference of at least 18°F (10°C) between interior and exterior temperatures.

    • Why: This pressure drives thermal energy through the walls, making invisible insulation gaps or thermal bridges clearly visible to our sensors.

  • Zero Solar Loading

    • Requirement: Inspection must occur before sunrise, after sunset, or on a heavily overcast day.

    • Why: The sun heats surfaces unevenly ("solar loading"). This artificial heat masks true internal heat loss, creating false positives and hiding real defects.

  • Low Wind Speeds

    • Requirement: Wind speeds ideally below 15 mph (approx. 6.7 m/s).

    • Why: High winds strip heat away from the building's surface (convective cooling) too quickly, washing out the subtle temperature patterns we need to analyze.

  • Dry Surfaces

    • Requirement: No precipitation within the last 24 hours; surfaces must be completely dry.

    • Why: Wet surfaces cool down via evaporation. This evaporative cooling looks exactly like a thermal anomaly, leading to inaccurate data.

2. Low-Slope Roofs (Moisture Entrapment)

Focus: Identifying wet insulation under the roof membrane.

  • High Solar Loading (Pre-Flight)

    • Requirement: A sunny, clear day prior to the evening inspection.

    • Why: We use the sun to heat the roof all day. Wet insulation holds this heat longer than dry insulation, creating the "thermal capacitance" contrast we look for.

  • The "Solar Window" (Timing)

    • Requirement: Flights occur strictly after sunset (dusk) but before dew settles.

    • Why: Once the sun sets, the dry roof cools instantly, while the wet areas glow warm. We fly during this specific window of maximum thermal contrast.

  • Clean Roof Surface

    • Requirement: Free of standing water, snow, or heavy debris.

    • Why: Puddles mask the temperature of the material beneath them. We need a clear line of sight to the roof membrane to detect the subsurface heat signature.

  • Low Humidity / No Dew

    • Requirement: Low ambient humidity to prevent rapid dew formation.

    • Why: Dew acts like a blanket of water, uniforming the temperature of the roof and erasing the thermal footprint of the trapped moisture below.

Action Required: Pre-Flight Checklist for your Sky Dog Inspection

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To ensure we capture the highest quality thermal data during your upcoming aerial inspection, we need your help creating specific environmental conditions at the site.

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Thermal cameras do not see visible light; they see heat energy. For us to detect insulation gaps or moisture entrapment, we need the building to "communicate" with our sensors.

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Please complete the following checklist 4 hours prior to our scheduled flight time.

1. Create the "Delta T" (Temperature Split)

Crucial for Exterior Wall Inspections We need a temperature difference of at least 18°F (10°C) between the inside and the outside of the building. This pressure difference forces thermal energy through wall defects, making them visible to our drone.

  • If it is COLD outside: Please turn your heating system UP.

    • Target: Ensure the interior is at least 72°F–75°F (22°C–24°C).

  • If it is HOT outside: Please turn your A/C system DOWN.

    • Target: Cool the building as much as reasonably possible to create contrast with the hot exterior air.

  • Timing: Adjust the thermostat at least 4 hours before our arrival to allow the wall materials to soak up the temperature change.

2. Stabilize the Building Envelope

  • Close all windows and external doors.

  • Close trickle vents.

  • Ensure that no large machinery or external exhaust fans are venting directly onto the walls we are inspecting, if possible.

3. Site Access & Safety

  • Unlock Gates: Please ensure we have ground access to the perimeter of the building for the pilot to maintain Visual Line of Sight (VLOS) with the drone.

  • Notify Security/Tenants: Please inform on-site security and tenants that a drone will be operating in the area to prevent alarm or interruption.

  • Lighting: If this is an evening/night flight, please turn off exterior floodlights if possible, as they can interfere with the thermal sensor's calibration.

 

Weather Disclaimer

As discussed, aerial thermography is strictly weather-dependent. If wind speeds exceed 15 mph, or if there has been precipitation (rain/snow) within 24 hours of the flight, we will need to reschedule. Wet surfaces create "evaporative cooling" which masks defects and results in unusable data.

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We will confirm the weather conditions with you 24 hours prior to the flight.

Thank you for helping us get the best possible results for your property.

Sky Dog Aerial Thermal Imaging www.skydogati.com

Providing thermal and mapping services to Hudson NH, Nashua NH, Manchester NH, Concord NH and the greater New England area.

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