Roofs
Slate, copper and tile roofs can last more than 50 years. Homeowners with wood shake roofs should expect them to last about 30 years, while fiber cement shingles last about 25 years and asphalt shingle/composition roofs last about 20 years, the NAHB found. Climate and weather conditions, such as snow, hail and hurricanes, can cut the life span of all types of roofs.
Air Conditioning System
Central air conditioning systems typically last 10 to 15 years. For a window air conditioner, InterNACHI suggests five to seven years. Having your unit serviced every year or two, keeping filters clean and trimming bushes around the outdoor unit can keep it working longer, but eventually the components wear out. Before you buy an air conditioning system, water heater or any other costly appliance, keep energy efficiency in mind to prevent your utility bill from soaring. You may also want to check with your utility provider to inquire if rebates or incentives for buying certain appliances are available, or consult EnergyStar.gov for additional tools and information.
Water Heater
A conventional electric or gas water heater typically lasts about 10 years. If you have a tankless water heater, expect it to stick around for about 20 years.