If you see fog or condensation between the panes of double-glazed windows, the seal is broken, and the window has lost its insulating value.

Check your phone's signal strength in various rooms.

Bring a marble or use a level app on your phone. If the floors slope significantly toward one side of the house, there may be a structural problem. 3. Water Damage and Plumbing

If a basement smells musty or damp, there’s a high probability of past or current leakage.

Ask for the roof’s age. Look for missing shingles, "cupping" (edges curling up), or heavy moss growth. Check the attic for water stains or daylight peeking through.

These are the most expensive items to repair or replace. If these are failing, you have significant leverage for negotiation.

Look for large, stair-step cracks in brickwork or gaps in the foundation.