A common question regarding Thermal Cameras are;
The answer is yes and no.
While Thermal Cameras cannot see through walls or glass, as they will detect the surface temperature of the first solid material you point at, what they can see is the heat given off (or taken away) from sources close to the wall giving us information about what is going on behind the wall. This would essentially enable you to be able to see what's going on inside or behind the wall and give you a lot of information that we cannot see with the naked eye.
As mentioned above, it's not possible for any thermal camera to see through any solid object. So how it works is that there is an object or substance that is causing temperature variance on the wall, floor or ceiling.
To check this; a wall, floor or ceiling has a uniform temperature which means that under normal circumstances the temperature is the same across the whole surface.
However, if you suspect poor insulation or wish to detect pipes behind the wall, this is possible.
Let's assume you have the heating on inside a room and its freezing cold outside. if there are holes in your insulation it will show up in blue spots on the screen compared to the rest of the surface. A well-insulated house will have uniform temperature across windows, doors, and walls throughout the day.
Thermal image of heat behind the wall
Thermal cameras focus on the infrared heat energy and converts it into colors that represent the different level of heat on the thermal images. Brighter colors such as red, orange or yellow represent warmer temperatures while darker colors like purple, blue or black indicate colder temperatures. From the image above, you can see that the television and the sofa are warmer compared to other objects. You can also see that parts of the wall are cooler than others and this is how it can detect what's happening behind a solid object, in this case, a wall.
By looking at the infrared image of the surroundings of the house, inspectors can tell whether insulation is needed or not by checking for things such as heat loss or air leakages. Other factors to be considered would be weather conditions or the shape of the home. To check if there are any gaps in the walls, inspectors would usually perform a test called blower door test, which would be done to check which exact spots causes the air leakages so that the necessary action can be taken.
An Infrared image of the wall will visibly show the drywall screws because of the difference in temperature between the drywall and screws. The same can be seen for the studs since wood releases heat at the different rate than metal screws and drywall. The temperature range can be adjusted depending on which part you would like to see more details of, whether it be the screws or the studs.
To have a well insulated home, inspections such as energy loss, HVAC, moisture, roof leaks and plumbing leaks should be inspected in addition to just inspecting the heat radiation behind walls. Thermal images can also see the differences in temperatures caused by insects, mold and moisture. With a good understanding of thermal imaging and the help of a knowledgeable inspector, any insulation problems can be quickly solved.
Moisture is nigh impossible to spot with the naked eye. You don't know its there until its too late and the room is moldy and products contaminated. Thermal Cameras do a great job in helping inspectors or site operators to inspect critical locations and check for moisture, before its too late.
To do this; simply scan locations prone to moisture exposure with the thermal camera and check if the heat is uniform. Places with moisture will show up colder to the surrounding area as the water draws away the heat. This can be picked up with a thermal camera or imager enabling preventative actions to tackle the issue.