by Scott Bane, InterNACHI® Certified Professional Inspector®
and Kate Tarasenko, Editor-in-Chief
A borescope is a tool designed to help an inspector visually inspect hard-to-reach, narrow and/or restricted areas. The borescope itself is a non-invasive tool, but damage can occur if drilling is done to view a closed-off area. Although a home inspector is not required to inspect systems or components that are deemed inaccessible, according to InterNACHI’s Home Inspection Standards of Practice, a borescope can be a valuable tool to help capture data of a property’s condition, and using a borescope can help you get a clearer idea of potential problems in areas that are just out of reach.
The borescope was invented in 1960 by prominent researcher and inventor Narinder Kapany. He was an Indian-American physicist who is considered the “Father of Fiber Optics,” and is also credited with coining that term. In addition to their use in communications, industrial and medical instrumentation, and lasers, fiber optics are used in high-end borescopes, as they allow the tool to translate information at high resolution in a non-destructive manner.
This tool can be used in a variety of inspection situations, including visualizing a chimney flue, looking behind walls near utility access points, looking behind home systems, and under appliances and around pipes. Another useful place to employ a borescope is in tight crawlspaces and attics, where spiders and other creatures you don’t want to encounter may take refuge.
Borescopes range in cost anywhere from $100 to the mid-five figures, depending on the brand and features. They can be operated with an exchangeable rigid or flexible extendable arm attached to a viewing lens or camera. High-end borescopes offer built-in lighting, infrared modes, adjustable zoom fiber-optic connections, and photo and/or video capability. Some models offer micro-SD ports for additional data storage. They come in waterproof models, and some have high-resolution viewing screens with adjustable contrast.
Most borescopes are designed to view and focus within 1 to 4 inches from the optical lens, with a digital zoom power of up to 5x. All optics have something called a field of view. The field of view is also referred to as the angle of view or aperture angle. The field of view is defined as a cone of vision that extends from the lens tip to a wide area, rather than a single focal point. With a wider field of view, more surface area can be observed. A borescope can have a field of view range of 10 to 90 degrees; 80 degrees and above is considered wide angle. The working diameter of a borescope is the outer diameter of the borescope’s shaft. The working length of the tool is limited by the length of the borescope’s shaft. The depth of field is the area that the borescope can give a focused image of the observed object. Some borescope tools have focus rings that can be adjusted to bring the observed area or object into clearer focus.
Some borescope models offer thermal imaging. Infrared thermography or thermal imaging is a non-invasive method that allows the inspector to identify temperature differences and anomalies that are imaged on a screen. Dark colors indicate cold or damp areas, and bright colors indicate hot areas. Thermal imaging can be used to help identify possible plumbing leaks, roof leaks, insulation deficiencies, and even hot spots in the electrical system through subtle temperature differences. For example, temperature differences near the roof line and between walls can be an indication of moisture and, consequently, potential mold issues. Many inspectors charge $300 to $500 for this service; some offer them free as part of their standard home inspection.
When using a borescope, care should be taken to maneuver the tool slowly and carefully through the given opening in order to observe the restricted area. If there is a focus ring, adjust the lens until the area or object of concern is clearly in view, and take photos in regular and infrared mode, if applicable. Using a borescope that has photo capability, the photos can then be transferred into your reporting software. If the borescope is not equipped with an internal camera, a digital camera or smartphone can be used to take a photo of the borescope’s screen, which you can then transfer into your home inspection report. If a light is not standard on the borescope, a small LED flashlight can be taped to the camera’s shaft to provide illumination.
A borescope should be kept in its protective case when not in use. The lens should be kept clean and free of debris. If the lens needs cleaning, a microfiber cloth and some glass cleaner should be used to avoid scratching. Borescopes do not require any kind of calibration, so dropping them does not make them less accurate, but should still be avoided.
Having the ability to inspect all areas of the home allows the home inspector to write the most robust and accurate report possible. Including photos of deficiencies in the inspection report gives the inspector the chance to explain more clearly a property’s condition and offers greater information to his/her client, as well as value to their service.
In short, a borescope is an invaluable tool that can greatly enhance a home inspector’s ability to inspect a property. Borescopes also allow inspectors to offer specialty inspections by exploring inside walls and other areas. It’s another useful tool that can expand the inspector’s services to help make them more money.
Scott Bane is a Certified Professional Inspector® and the owner-operator of Bane Industries, his home inspection business based in Erie, Pennsylvania. Scott is also a PA-licensed pest control applicator. He attended the University of Maryland and Penn State, and earned his Bachelor of Business Administration from Loyola University in New Orleans. Scott is also a U.S. Army veteran.
Take InterNACHI's free, online Infrared Thermography Inspection Training Course
Take InterNACHI's free, online Building Science and Infrared Thermal Imaging for Inspectors Course