Mechanicals to Ask About Before You Make an Offer

A guide to the furnace, water heater, insulation, and other mechanical questions worth asking before buying a house.

Most buyers walk through a house looking at finishes: paint, flooring, countertops. These are the easiest things to change later and the least useful things to focus on when deciding whether a house makes financial sense to run.

The mechanicals are the part of the house doing the actual work of keeping it comfortable, and they are also the part most buyers know the least about. Start with the furnace or heat pump. Ask its age, when it was last serviced, and whether it was sized correctly for the house. An oversized or undersized system can run inefficiently no matter how new it is.

Ask about the water heater in the same way. Tank or tankless, its age, and its fuel source all affect ongoing cost. Ask about insulation, not just whether it exists but where: attic, walls, and crawlspace or basement can all have different levels, and gaps between them matter more than the total amount installed.

Windows are worth asking about directly rather than assuming from their appearance. Double-pane glass does not guarantee a tight seal, and older windows that look fine can still leak significant air around the frame.

If any of this information is not readily available, it is reasonable to ask for it as part of your offer process, or to have it evaluated before you finalize a purchase. A house that looks finished on the surface can still have real gaps in the systems that determine what it costs to live in.

Asking these questions early does not mean assuming a house is a problem. It means understanding what you are actually buying before you buy it.