- Lead is a toxic metal that was once commonly used in the manufacture of household paint and plumbing fixtures, and as an additive to gasoline. While it has long been prohibited in new construction, lead-based paint and plumbing that weren't removed may present a significant health hazard. Homes constructed
prior to 1978 may contain lead paint, which can be ingested by small children or contaminate surrounding soil and vegetable gardens. It is easily identifiable by its alligator-like flaking pattern. Lead pipes, too, were used in homes up until the late 1940s, and they may allow lead to leach into drinking water. They can be identified by their dull gray color and the ease by which they can be scratched by keys or coins.
- Asbestos insulation, which can increase the chances of developing lung cancer and mesothelioma, was used in homes between 1930 and 1950. Asbestos insulation should be left undisturbed until it can be removed by a qualified professional, as its fibers can be inhaled when they are airborne, creating a significant health hazard.
- Older homes were not constructed to meet modern energy efficiency requirements. They may suffer thermal losses from single-pane windows, insufficient or compressed insulation, leaking ductwork, and inefficient heaters and other appliances. It should be noted, however, that older homes better capitalize on natural sources of lighting, heating and ventilation through the use of design features such as exterior shutters, shade trees, and thick, heat-retaining masonry walls.
- Buried oil tanks were often abandoned and forgotten after homes switched to newer fuel sources. Today, these tanks pose a safety hazard to homeowners and their neighbors, as their contents may leak into surrounding soil. Disposal guidelines vary and may call for removal of the tank or filling it with sand or gravel. Soil testing may be required to investigate whether an abandoned fuel tank has leaked underground.
- knob-and-tube (K&T) wiring. This was an early standardized method of electrical wiring in buildings from about 1880 to the 1940s. While codes do not require its removal, K&T wiring often suffers from unsafe modifications, old age, overheating, and lack of a ground wire. It can be identified by its characteristic porcelain insulating tubes;
- a lack of ground-fault circuit interrupters (GFCIs). Homes built before the 1970s may not have been equipped with GFCI protection, which guards against overloads, short circuits and ground faults; and
- a lack of grounded receptacles, which provide a safe path to ground for stray electrical current. Most major appliances, such as stoves, refrigerators and computers, have three-prong plugs and require three-slot or grounded receptacles. Homes in the U.S. built before 1962 were not constructed with three-slot receptacles.
- Wells, cesspools and septic tanks were commonly used before homes and buildings were connected to public sewer and water systems. If they were abandoned and not removed, these elements pose hazards related to their deterioration and collapse.
- Radon is a naturally occurring gas that has been identified as the second leading cause of lung cancer in the United States. It usually enters the home through cracks in the foundation, a common problem found in vintage construction. Radon cannot be seen, smelled or tasted, so concerned homeowners should consult with their InsideOut inspector about radon testing during their next scheduled inspection.