“Infrared thermography is the use of infrared radiation to…express heat signatures and heat differences. Infrared inspection can help identify water intrusion, missing insulation, insulation deficiencies, heat or energy loss areas, air leakage points. An infrared camera can help the inspector “see” when no other tool can provide enough information.”
(The quote above and much of the images and information below are reproduced from the International Association of Certified Home Inspectors certified training pages.)
The eye cannot see infrared radiation. In order to get an infrared image, a detector is used to detect the wavelength of the radiation. This wavelength is related to a specific temperature, and a color is then assigned to that temperature or wavelength.
A home thermographic inspection is Qualitative, not qualitative.
Qualitative measuring includes:
- analysis of image;
- gauging apparent temperature;
- finding anomalies;
- finding location; and
- analyzing patterns.
Quantitative measuring includes:
- taking temperature measurements;
- making compensations; and
- classifying the seriousness of anomalies.
There is generally no need for determining exact temperatures in a home inspection.If a moisture spot in the ceiling appears during inspection in the pattern shown on my IR camera, the temperature of the moisture is irrelevant. For our purposes, only the pattern is relevant.
In the above image the location of an apparent moisture leak is revealed by the pattern, not the temperature. (The inspector would then employ other means, such as a moisture meter, to confirm). Apparent temperature is all that is required from the IR camera to assist in locating defects.
The following images were taken in the United States. Some of the systems and situations encountered do not apply to residences in Israel. Their value, then, is to generally illustrate the power of Thermography.
Interpreting Infrared Images
Water infiltration is indicated by certain shapes of colder or warmer areas.
- A puddle-like appearance indicates leaks, and spread out from one spot.
- Wicking occurs when water appears to flow upward. This is seen in wood, drywall and brick.
- Well-defined fold spots between joists with some spread beyond the joists should be noted.
- Always back up your initial suspicions with moisture-meter readings or further inspection from the attic, roof, etc.
Above is a gutter with no downspout which empties onto the roof at the open gutter end. Excessive water flowing down the roof at one area can overflow and damage the flashing and penetrate into the sheathing of the dormer.
This image shows the inside. Note the accumulation of the water just above the reticule, and the generalized wicking of moisture to the entire area at the angle of the roof. This shows the importance of proper interpretation.
Above, we see another indication of a common problem. The duct was not properly insulated and sealed in the attic, and condensate moisture from the cold duct is leaking into the drywall. This is commonly seen on the second floor of larger houses where the colder duct meets the humid air from the attic area. The duct should be properly insulated and sealed against humid air.
Here is something commonly seen in attic ductwork. The duct connections are not properly insulated. This causes heat loss in the winter and condensation in the summer.
Here we see a common problem. This ceiling can-type light allows hot, moist air to escape through holes in and around the can. This hot, moist air hits the cold attic air and condenses, leaving water to accumulate on the ceiling and the joists. The slow and steady accumulation may cause mold growth and greatly deteriorate the drywall and the wood before displaying itself visually, without infrared imaging.
It is always best to find problems when they are small and easy to fix, rather than after they have done considerable damage.
Here is an example of water in exterior materials. There is an apparent roof leak at the wall-roof junction in a commercial building. The exterior of the building is constructed with an Exterior Insulation Finishing System, EIFS, and water has infiltrated past the flashing and accumulated in the foam backing below the flashing.
This image shows moisture intrusion around the chimney above a fireplace. The older plaster and lathe wall show no other indications of water. Moisture in the chimney chase that would not otherwise have been detected until it was too late!
courtesy of InterNACHI member John McKenna, CMI
These images show an interior wall with a vinyl siding exterior. It has a smaller roof over the corner section with no flashing tins.
The thermal image of the wall corner displays extensive water infiltration where the roof-wall junction was not properly flashed.
Most air leaks occur in floors, walls and ceilings. Unsealed interior HVAC ducts are the second most common location for leaks. Fireplace installation and exterior and plumbing penetrations are the third most common.
These images show an exterior ceiling-wall interface. Thermal imaging shows hot-air infiltration where the rim joist is not properly sealed.
The same effect can be seen with cold air infiltration.
Weatherstripping and improper door positioning can also cause air infiltration.
Thermal imaging can reveal moisture in the closed-cell material behind the surface, which is generally caused by moisture wicking from the grade flashing.
This images show leakage from the downspout and gutter behind the wooden siding.
photos courtesy of Scott Wood
Here, it had rained recently. If it had not, this defect may have not been clear.
This image shows leakage around the window frame because of failed flashing.
pictures courtesy of Scott Wood
What is the cause of this colder area at the exterior corner of the house? Is this a problem with the flashing between the stucco and the brick? No. It’s just from watering the lawn. The picture above was taken three hours after the watering stopped.
Because of the difference in thermal masses of different building materials, they will absorb and radiate heat, and infrared light, at different rates. This leads to the “see-through-the-wall” illusion of thermal imaging. That is not the case.
Here we see a ceiling joist structure. Note that the Laminated Veneer Lumber (LVL) joists on the right are slightly cooler (and have slightly greater density and thermal mass) than the dimensional lumber joists on each side. The denser and usually stronger structural members are slower to absorb and radiate heat.
These images show a bedroom wall, as seen in visible and infrared light. Note the studs, the insulation gap at the top, and the colder readings at the inside corner where the double studs are.
This is the gabled end of a cathedral ceiling. Note the studs and the ceiling joists with blocking. What is that glow in the upper right-hand corner?
These are structural members in a stepped ceiling.
This picture shows triple studs at a joist that supports a double joist under a wall on the upper floor.
Water freely flows throughout most houses. It’s called plumbing. Pipes leak. Drain pipes get clogged and back up. Plumbing fixtures come loose and allow water to go where it’s not supposed to go. Pipes in houses can also carry heated water and steam for heating. When evaluating the plumbing in a house, all the water sources (sinks, basins, bathtubs, dishwashers) should be run for at least five minutes to properly illustrate the pipe positions and allow leaks to form. It is best to run hot water in the winter and cold water in the summer to obtain the proper temperature difference for imaging.
Here is a classic problem. Improper sealing of the plumbing fixtures to the tile shower enclosure has lead to water infiltration behind the wall.
This shows ceiling water from a leaky toilet wax ring. It is just as important to scan interior walls and ceilings as it is to check exterior walls.
picture courtesy of Jeff Pope
Whenever electrical power flows, some of the current is converted into heat. Higher temperatures in electrical wiring is common. Much higher temperatures is not. Just because something is hot (or cold) does not necessarily mean it is defective. In some cases, relative temperature differences revealed by the colors of an infrared image are not conclusive. Actual temperature readings may be needed to determine if problems exist. The clear recommendation for some electrical issues would be to consult an expert to evaluate the load(s).
Visual inspection of a ceiling fan switch reveals no apparent problems. Thermal imaging reveals a hot switch. Note the warmth in the shared hot wire with the other switch. Why is the one switch hotter?
This image shows an electrical distribution panel in a condominium unit. No apparent problems are seen. What does thermal imaging show?
The GFCI breaker at the upper left is warm and the breaker (and wire) at the lower right is also warmer. When the dead front was removed, the GFCI breaker started to arc. The breaker at the lower right was rated for 15 amps, but was supplying a 20-amp furnace blower motor.
Upon closer examination, the greatest temperature difference can be seen where the breaker attaches to the buss bar, where the arcing is occurring.
The above shows a rectangular air-return duct in a plaster wall. Where was the duct installed? Note thermal images during both heating and A/C operation.
This is a duct encased in a ceiling soffit in a finished basement. Note the framing of the soffit, as well as the hot spot at the far end, where the duct had been physically damaged.
Here we see a branch duct off the main duct and its termination at a supply register.
This shows hydronic heating pipes under the floor in an office building floor.
This shows radiant heating pipes under tile flooring. Note the rug and sofa.
A leaking hydronic heating pipe in a slab floor at the wall is shown here.
This shows a concrete slab construction with radiant heat. Using thermal imaging, the placement of the pipes can be seen, and any leakage can be noted.
This is a barrel-style ceiling in an older house with a substantial radiant heating system in the ceiling.
This driveway is heated with heat pipes. The upper section was not functioning and the client wanted the leak point located.
With careful adjustment of the span and level of the image, pipe leaks can be localized.
Adjustment of the span, level and reflectivity settings of the camera, environment permitting, can enhance exterior scanning. Here, we see the lines of a heat pump system running inside the wall to the attic air-handler system.