What to check by the year it was built

A house from the first decade of the 1900s has been rewired, replumbed and reroofed, often several times. What remains original tends to be framing, plaster, trim and paint, which is where the age-specific checks are.

Homes of the 1910s often still have plaster walls, old-growth framing and layers of paint. Systems have usually been replaced, but you rarely know when.

The 1920s building boom left many bungalows and revivals. Paint, plaster, early insulation and the water service line are the age-specific questions.

Depression-era houses were often modest and modified later. Look at what was added: insulation, heating and wiring changes.

Wartime and early postwar houses used new materials fast, including asbestos-containing products. Lead paint and lead plumbing remain likely.

The postwar boom: slab and crawlspace ranches, early central heating, and widespread asbestos-containing tile, siding and pipe insulation.

Houses of the 1960s added central air and bigger electrical loads; late in the decade, aluminum branch wiring appears.

The 1970s span the aluminum-wiring years, the end of residential lead paint (1978) and the federal safety-glazing standard (1977).

Homes built in the 1980s are after the lead-paint ban but before the 1986 lead-free plumbing rule took full effect; original AC systems used R-22.

By the 1990s lead-free plumbing rules and garage-door entrapment protection (1993) apply; original HVAC from this era used R-22 and is well past typical life.

Homes of the 2000s are young structurally, but their first water heaters, AC systems and roofs are at or past typical replacement age. Imported problem drywall is a possible issue for 2001–2008 builds and renovations.

A 2010s house is past the R-22 era; its first water heater and AC are approaching replacement age, and the next AC will use a new refrigerant.