Roof, electrical, and HVAC defects home inspectors flag most

Roof, electrical, and HVAC defects show up on more inspection reports than any other system in the house. Industry research on tens of thousands of inspection reports, compiled in RapidEye's 2026 home inspection industry statistics, puts roof issues at close to 20 percent of reports and electrical problems right behind at nearly 19 percent, with windows, gutters, and plumbing rounding out the top five. HVAC trouble is not far behind once you count dirty filters, leaky ducts, and aging furnaces. If you inspect homes for a living, you already know why: these three systems are big, they age fast, and past owners love to patch them with a quick DIY fix instead of a real repair.

This post walks through the exact defects that show up again and again on roofs, electrical systems, and HVAC equipment. We will cover why each one matters, what a buyer or seller should do about it, and how PadInspector helps you document every one of them without losing an hour of your day to typing.

What counts as a home inspection defect?

A defect is anything that is not working the way it should, is unsafe, or is close to the end of its useful life. Some defects are small, like a loose gutter screw. Others are big, like a cracked heat exchanger that can leak carbon monoxide. A good inspector notes both kinds, because a buyer needs the full picture before closing.

Not every defect is a deal breaker. Most homes, even nice ones, have several small issues. The goal of a report is not to scare anyone. It is to give a clear, honest list so the buyer knows what they are getting and what it might cost to fix.

What are the most common roof defects inspectors find?

The roof takes the most weather damage of any part of a house, so it is no surprise it tops the defect list. Sun, wind, hail, and freeze-thaw cycles all chip away at roofing material year after year.

Missing, cracked, or curling shingles

Shingles dry out and curl as they age, and wind can rip them off entirely. Once a shingle is gone or cracked, water has a straight path into the roof deck. ASHI's guide for homebuyers on roofs notes that a typical roof lasts 20 to 30 years depending on the material and how well it was installed, so age alone is a strong clue that shingle damage is coming.

Bad flashing around chimneys, vents, and skylights

Flashing is the thin metal that seals the joints where the roof meets a chimney, vent pipe, or skylight. It is a small part with a big job. When flashing rusts, cracks, or was installed wrong in the first place, water sneaks in at exactly the spot the flashing was supposed to protect. Inspectors covering this topic at HC Inspectors' roof defect guide list damaged flashing as one of the most frequent roof call-outs on their reports, right alongside clogged gutters and loose shingles.

Poor attic ventilation

A roof needs to breathe. Without enough intake and exhaust vents, heat and moisture build up in the attic. That trapped heat can bake shingles from underneath and shorten their life, while trapped moisture feeds mold and rot in the wood deck. InterNACHI's ten-step roof inspection training walks through checking ventilation, flashing, and drainage as core parts of every roof inspection, not optional extras.

A quick roof example

Picture a 22-year-old roof with a few curled shingles near the ridge, rusty step flashing at the chimney, and almost no soffit vents. None of those three things alone would fail the house. Together, they tell a buyer this roof needs a real budget line within the next year or two, not just a patch job.

What are the most common electrical defects inspectors find?

Electrical problems are the second most reported issue nationwide, and they carry real safety weight. According to NFPA's research on home fires from electrical distribution and lighting equipment, electrical failures cause an estimated annual average of 527 civilian deaths, 1,580 injuries, and 2.4 billion dollars in direct property damage in the United States. That is not a rare event. It is a steady, ongoing risk in older homes.

Missing GFCI protection

Ground fault circuit interrupters cut power in a flash if they sense current going somewhere it should not, like through a person. They belong near water: kitchens, bathrooms, garages, and outdoor outlets. The Consumer Product Safety Commission's GFCI fact sheet explains that a GFCI can shut off power in as little as one-fortieth of a second, fast enough to prevent a serious shock. Homes built before GFCIs were standard often still have none installed, and that gap shows up constantly on inspection reports.

DIY wiring and reversed polarity

Every inspector has a story about a "handyman special" wiring job. Reversed polarity, mismatched wire gauges, and open splices without a junction box are all signs someone skipped a permit and a professional. These fixes are usually cheap to correct, but they are still a real shock or fire hazard until an electrician sorts them out.

Overloaded or outdated panels

Older homes were wired for a much smaller electrical load than modern life demands. Add central air, an electric range, a home office, and a couple of EV chargers, and an old 100-amp panel starts to strain. Double-tapped breakers, rust inside the panel, and outdated fuse boxes all point to a panel that needs an upgrade before it becomes a hazard.

What are the most common HVAC defects inspectors find?

Heating and cooling equipment does not always get its own line in defect studies, but it drives plenty of comfort complaints and a few genuine safety issues. It also tends to hide its problems behind a closet door, so buyers rarely think to check it themselves.

Dirty filters and weak airflow

A clogged filter is the simplest problem on this whole list, and also one of the most common. It forces the blower motor to work harder, cuts efficiency, and can even cause the system to freeze up or overheat. It is an easy fix, but it is still worth flagging so a new owner starts off on the right foot.

Leaky, uninsulated ductwork

Ducts running through an attic, crawlspace, or unconditioned basement lose a shocking amount of conditioned air if they are not sealed and insulated well. The ENERGY STAR duct sealing guide estimates that a typical home loses 20 to 30 percent of the air moving through its duct system to leaks and poor connections, and that number climbs even higher when ducts sit in an attic or crawlspace. That is real money leaking out of a house every single month.

Cracked heat exchangers and combustion safety

This is the HVAC defect that matters most for safety. A cracked heat exchanger in a furnace can let combustion gases, including carbon monoxide, leak into the air a family breathes. Carbon monoxide has no smell and no color, which is exactly why it is so dangerous. The CDC's carbon monoxide overview reports that more than 400 Americans die every year from unintentional CO poisoning that is not linked to a fire, with over 100,000 people needing emergency care. A furnace that shows scorch marks, rust, or an odd smell near the burner deserves a hard look and, often, a referral to an HVAC pro.

Roof, electrical, and HVAC defects at a glance

Here is the same list in one place: the defect an inspector runs into most on each system, and why it earns a line on the report.

Why do these three systems top the list every year?

Roof, electrical, and HVAC problems dominate reports for a few simple reasons:

• All three sit outside daily view, so small issues get ignored until they grow.
• All three take real weather or wear-and-tear damage over time.
• All three get touched by past owners doing their own repairs to save money, which does not always end well.

What should a buyer or seller do with roof, electrical, and HVAC findings?

A defect on the report is not automatically a reason to walk away from a sale. It is information. Buyers can use findings to ask for a repair credit, negotiate the price, or simply plan a budget for the first year in the home. Sellers who get ahead of these three systems before listing, especially a leaky roof or an outdated panel, often avoid a scramble during the option period.

The smartest move for both sides is to separate safety issues, like a cracked heat exchanger or an exposed wire, from maintenance issues, like a dirty filter. A clear, well-organized report makes that split obvious at a glance instead of burying it in fifty pages of photos.

How PadInspector helps with roof, electrical, and HVAC defects

PadInspector is built for exactly this part of the job. Instead of scribbling notes on a clipboard and typing them up later, you walk the roof, the electrical panel, and the mechanical closet while talking out loud. PadInspector transcribes what you say and attaches your photos to the right area automatically, so a shingle problem, a panel photo, and a furnace shot all land where they belong without you touching a keyboard.

Because roof and electrical defects often tie back to local code, PadInspector's automatic building-code-violation lookup flags issues as you go, saving you from digging through a codebook between appointments. The app also logs the weather on inspection day, which matters a lot for roof and moisture findings: if a client questions a leak call weeks later, you have a record showing it was dry that day, protecting you from liability. And since the whole system works fully offline, a weak signal in an older house with a metal roof or a basement mechanical room never slows you down. See the full PadInspector feature list for everything the app covers.

If you run a team, PadInspector's multi-inspector mode also keeps roof, electrical, and HVAC findings organized across every inspector, so nobody re-checks the same panel twice or misses a defect because notes got lost between two people's phones.

FAQ: Roof, electrical, and HVAC defects

What is the single most common defect home inspectors find?

Roof issues top most industry studies, sitting close to 20 percent of all inspection reports. Electrical problems come in a close second. Both age quietly and often get patched instead of properly repaired, which is why they show up so often.

Do roof or electrical defects always mean a bad deal?

No. Most findings are normal wear that comes with an aging home. Buyers can usually negotiate a repair credit or price adjustment instead of walking away. The real red flags are safety issues, like exposed wiring or a cracked heat exchanger, that need quick attention.

Why do electrical defects get flagged so often?

Older homes were wired for a smaller electrical load than modern families use, and past owners sometimes did their own wiring without a permit. That combination of age and DIY work creates the missing GFCI outlets, reversed polarity, and overloaded panels inspectors see all the time.

Is a dirty HVAC filter a serious problem?

Not usually, but it is worth noting. A clogged filter forces the system to work harder, wastes energy, and can shorten the equipment's life. It is one of the easiest and cheapest fixes on any report.

What HVAC defect is most dangerous?

A cracked heat exchanger is the top concern because it can let carbon monoxide leak into the living space. Carbon monoxide has no smell or color, so a furnace showing rust, scorch marks, or an odd odor near the burner deserves a closer look and often a referral to an HVAC technician.

How can an inspector document these defects faster?

Voice-driven tools like PadInspector let you describe a defect out loud while you are standing right in front of it. The app transcribes your notes and attaches the photo to the correct area automatically, so the report is nearly done by the time you climb down off the roof.

Ready to spend less time typing up roof, electrical, and HVAC findings and more time inspecting? Request an invite to PadInspector and see how much faster your reports can go out the door.