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Used House Inspection Checklist: 12 Things First-Time Buyers Miss

June 12, 2026

A home inspector spends three hours at the property and delivers a 40-page report. That sounds thorough until you realize they can’t see through walls, they don’t test every outlet, and they aren’t the ones who’ll live with the problems they miss. Most first-time buyers treat the inspection report like a warranty. It’s not. It’s a snapshot taken by someone who got paid whether they found everything or not.

I’ve walked through a dozen used houses with friends who were buying, and I’ve missed things myself on my own purchases. Here are twelve items that routinely slip past both buyers and inspectors — and how to check them yourself.

1. Windows and Doors That “Sort of” Work

A window that sticks halfway up isn’t just annoying — it’s a fire escape that doesn’t escape. Open and close every window and exterior door. Feel for drafts around the edges. A door that won’t latch properly could mean a shifted frame, which could mean foundation movement. If the sellers have strategically placed weatherstripping or draft stoppers, ask yourself what they’re hiding.

2. The Cabinets Under Every Sink

This is where water damage lives. Open the cabinet doors under the kitchen sink, every bathroom sink, and anywhere there’s a plumbing connection. Look for water stains, swollen particleboard, mold spots, or that musty smell that says “this has been leaking for a while.” Shine a flashlight at the back panel. Press the floor of the cabinet with your fingers — if it’s soft, water has been sitting there.

A moisture meter costs $30 and removes the guesswork. I bring one to every walkthrough now.

3. The Roof, From the Ground

You don’t need a ladder. Walk to the street or the far corner of the yard and look up. Missing shingles. Curling edges. Sagging ridge lines. Dark patches that might be moss or might be rot. Check the gutters from below too — if they’re pulling away or overflowing, drainage has been neglected. Roof replacement costs five figures. Your inspector will note obvious damage. They won’t always catch a roof that’s on year 18 of a 20-year lifespan and looks “fine for now.”

4. Electrical Outlets, Every Single One

A home inspector tests a representative sample. That means some outlets never get checked. Bring a plug-in outlet tester — the kind with three lights that reads open ground, reversed polarity, or missing neutral. Test every outlet you can find, especially in older homes where a previous owner may have done their own wiring. I found an ungrounded outlet behind a couch in a house I almost bought. The inspector missed it because the couch was in the way.

5. The Foundation, Inside and Out

Walk the exterior perimeter. Cracks wider than 1/8 inch deserve a second look. Stair-step cracks in brick or block walls are a red flag. Inside the basement or crawl space, look for horizontal cracks — those are worse than vertical ones because they mean the wall is bowing under soil pressure. Check for water stains on the floor or at the base of walls. A damp basement after three dry days means the drainage problem is permanent, not weather-related.

6. HVAC That “Turns On” but Doesn’t Actually Work

Flipping the thermostat and hearing a fan run isn’t enough. Let the heat run until it reaches the set temperature. Do the same with the air conditioning. Check the temperature at a vent with a thermometer. Listen for grinding, rattling, or cycling on and off too frequently. Ask for utility bills from the past 12 months — if the heating cost is double what comparable homes pay, the furnace is limping along and you’ll be the one to replace it.

7. Utility Bills the Seller Doesn’t Want to Share

A seller who refuses to provide 12 months of electric, gas, and water bills is hiding something. High water bills might mean a leaking pipe or a failing water softener. Spiking electric bills in winter could mean a heat pump that switches to expensive resistive backup heat. Compare the usage to similar homes in the area. Data doesn’t lie the way fresh paint does.

8. Grading and Drainage Around the Foundation

Stand at one corner of the house and look along the foundation line. The ground should slope away from the house — at least 6 inches of drop over the first 10 feet. If the soil slopes toward the foundation, or if there are flower beds mounded up against the siding, water is being directed into the basement or crawl space. Downspouts should extend at least 4 feet from the foundation. If they dump water right at the corner, you’re looking at a future leak.

This is the most boring thing on the list. It’s also the one that causes the most expensive damage over time.

9. GFCI Outlets in Wet Areas

Kitchens, bathrooms, garage, exterior outlets, and laundry rooms should all have GFCI protection. Press the TEST button, then the RESET button on each one. If TEST doesn’t click, or if RESET won’t stay in, the outlet is dead. Non-functioning GFCIs in a house built after the 1970s usually mean the wiring was never updated — and that’s a bigger electrical project than swapping a few outlets.

10. Chimney and Vent Terminations

From the ground, look at the chimney cap. Missing or cracked. Look at the mortar joints between bricks. Crumbling mortar lets water in. Check vent pipes coming through the roof for rust or missing caps. A damaged flue isn’t just a water leak — it’s a carbon monoxide risk if combustion gases can’t vent properly. Inspectors check the firebox. They don’t always check the top of the chimney.

11. Attic Insulation Depth and Condition

If the attic access is safe to peek into, bring a flashlight and look. Fiberglass or cellulose insulation should be at least 12 inches deep across the entire floor. Less than that in a cold climate means high heating bills. Look for compressed areas where someone stored boxes on top of the insulation — compressed insulation loses its R-value. Check for dark spots that mean moisture or rodent activity. If you see daylight through the roof decking, you have holes.

12. Main Sewer Line Material

Ask what the sewer line is made of. If the seller doesn’t know and the house is pre-1980, assume the worst. Orangeburg pipe — basically tar paper formed into tubes — was used from the 1940s to the 1970s and fails catastrophically. Clay pipes crack and let roots in. Cast iron rusts from the inside out. Replacing a sewer line under a front yard costs anywhere from $3,000 to $15,000 depending on depth and length. A standard home inspection does not include a sewer scope. Pay the extra $200 to $400 for one. It’s the best money you’ll spend during due diligence.

Final Advice: Bring Someone Who Owes You Nothing

Bring a friend, a parent, or anyone who isn’t emotionally attached to the house. You’ll be standing in the kitchen imagining where the coffee maker goes. They’ll be looking at the water stain on the ceiling. That second pair of eyes is worth more than anything on this list.

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