What Does a Home Inspector Check?
A certified home inspector evaluates 400+ components across all major systems of a property — from the foundation footing to the ridge cap. Here's a complete breakdown of every system inspected, what inspectors look for, and what falls outside the scope of a standard inspection.
Structural System
Foundation, basement walls, crawlspace, load-bearing walls, floor joists
Poured concrete, concrete block, stone rubble, or slab — inspectors look for cracks (horizontal cracks in block walls are a serious warning), bowing, settlement, and signs of water intrusion. Horizontal cracking typically indicates lateral soil pressure and warrants structural engineering evaluation.
Checked for efflorescence (white mineral deposits signaling water migration), active seepage, staining, and structural cracks. Inspectors probe for soft spots in block mortar.
Inspector enters accessible crawlspaces to check for standing water, wood rot, pest damage, vapor barrier condition, insulation installation, and clearance between wood and soil (minimum 6 inches per most codes).
Visually assessed for plumb and alignment. Sagging rooflines, bouncy floors, or doors that don't close squarely can indicate load-bearing wall issues.
Inspected from below (basement or crawlspace) for notching, cutting, pest damage, rot, and improper spans. Sistered joists and improper modifications are documented.
Roof System
Shingle condition, flashing, gutters, soffit/fascia, attic access from roof
Inspectors assess granule loss, curling, cupping, blistering, missing shingles, and estimated remaining life. Three-tab shingles have a 15–20 year life; architectural shingles 25–30 years. Roof age is often listed in the inspection report.
One of the top sources of roof leaks. Step flashing, counter flashing, and chimney saddles are checked for separation, rust, improper sealant use (a common DIY mistake), and missing sections.
Checked for proper pitch, secure attachment, joint separation, rust, and downspout discharge location. Downspouts should discharge at least 6 feet from the foundation.
Wood rot in soffit boards is a common finding, particularly on older homes. Fascia boards support gutter hangers — rot here can cause gutter collapse.
Roof-mounted vents, ridge vents, and any visible sheathing from roofline perspective are assessed. Active leaks or staining on sheathing visible from the exterior indicate a problem.
Electrical System
Service entry, panel, breaker types, AFCI/GFCI, aluminum wiring, knob-and-tube
Inspectors identify the service entry (overhead vs. underground), amperage (60A is undersized for modern loads; 100A minimum, 200A standard for most homes), and panel manufacturer. Zinsco and Federal Pacific Stab-Lok panels are flagged as safety hazards due to documented breaker failure rates.
Double-tapping (two wires under one breaker terminal), oversized breakers, and tripped breakers are documented. Breaker condition and labeling accuracy are checked.
GFCI (Ground Fault Circuit Interrupter) protection is required by modern codes at all wet locations — kitchens, bathrooms, garages, outdoors, and unfinished basements. AFCI (Arc Fault) breakers are required in most living areas per NEC 2014+. Older homes missing these are noted.
Used extensively in homes built between 1965–1973 as a copper substitute. Aluminum wiring expands and contracts more than copper, causing loose connections and overheating at outlets. This is a significant red flag requiring remediation by a licensed electrician — either pigtailing with copper or full rewire.
Found in homes built before 1940. Open air wiring with no ground conductor. Problems arise when insulation is piled on top (creates fire hazard) or when circuits have been modified improperly. Many insurers won't cover homes with active knob-and-tube. Inspectors assess condition and extent.
Plumbing System
Supply line material, water heater, fixtures, drain speed
Copper remains the gold standard — inspect for blue-green corrosion at joints. PEX (cross-linked polyethylene) is modern and flexible. Galvanized steel pipe in homes older than 40 years is often heavily corroded internally, reducing water pressure and eventually failing. Polybutylene (gray plastic, 1975–1995) is a recalled material that failed in large numbers — a significant finding.
Age, capacity, temperature/pressure relief valve condition, flue venting (for gas units), anode rod access, and evidence of leaks are all evaluated. Most water heaters last 8–12 years. Gas units are checked for proper draft and combustion air supply.
Every faucet, toilet, tub, and shower is operated. Inspectors look for leaks under sinks, slow drainage, toilet rocking (loose wax ring), and adequate water pressure. Flexible braided supply lines to toilets and sinks are checked for age — these fail without warning after 10 years.
Each drain is run and observed. Slow drains can indicate partial blockages, inadequate venting (gurgling drains), or more serious line issues. Drain speed and gurgling are documented for all fixtures tested.
HVAC System
Furnace age/BTUs, heat exchanger, AC refrigerant, ductwork, filter, exhaust vents
Furnaces last 15–25 years. Age is typically found on the data plate or encoded in the serial number. Inspectors note estimated remaining life and BTU output. Undersized equipment for home square footage is flagged.
Cracked heat exchangers allow combustion gases (including carbon monoxide) to enter living spaces — one of the most serious HVAC findings. Visual inspection is performed; definitive diagnosis often requires an HVAC technician with combustion analyzer.
Inspectors operate the AC system when ambient temps allow (typically above 60°F). They check temperature differential at supply vents (should be 14–22°F below return air temp), condition of the condenser unit, and signs of refrigerant leakage (ice on lines, oil staining at fittings).
Supply and return registers are assessed. Disconnected duct segments in attics or crawlspaces (conditioning unconditioned space), crushed flex duct, and dirty ductwork are commonly noted.
A clogged filter signals poor maintenance. Inspectors check filter size and condition. Restrictive or missing filters, and non-standard filter locations, are documented.
Combustion appliances require proper venting to outdoors. Inspectors trace gas furnace and water heater flues, checking for backdrafting, proper pitch, and secure connections. Disconnected flue segments in attics are a life-safety issue.
Windows & Doors System
Seals, operation, locks, storm windows
Failed IGU (insulated glass unit) seals appear as fogging or condensation permanently between panes. This reduces thermal efficiency but is cosmetic in terms of structural impact. Every accessible window is checked.
All windows are opened and closed where accessible. Painted-shut, swollen, or inoperable windows are documented. Egress windows in bedrooms must meet minimum size requirements per code (typically 5.7 sq ft openable area, 24 inches height, 20 inches width).
All interior and exterior doors are operated. Inspectors look for doors that don't latch, stick seasonally (indicating settling or moisture issues), missing strike plates, and inadequate locks on exterior doors.
Presence and condition of storm windows is noted. Missing or damaged screens are documented as minor deficiencies.
Attic System
Insulation depth, ventilation, signs of leaks, vermiculite note for pre-1980
DOE recommends R-49 to R-60 in attics for most of the US. Inspectors measure insulation depth in multiple locations. Cellulose, fiberglass batts, blown-in fiberglass, and spray foam are identified. Missing insulation over the top plate (the most common installation error) is flagged.
Balanced attic ventilation prevents summer heat buildup and winter condensation. Inspectors assess the ratio of intake (soffit) vents to exhaust (ridge, gable, or power) vents. Blocked soffit vents are one of the most common attic deficiencies.
Stained sheathing, discolored rafters, and mold growth indicate past or current roof leaks. Inspectors photograph evidence of water intrusion and identify the likely entry point.
Vermiculite attic insulation — a gray, pebble-like material — was commonly contaminated with asbestos, particularly ore from the Libby, Montana mine. If present in a home built before 1990, inspectors flag it and recommend testing before disturbance. Do not disturb vermiculite without prior testing.
Garage System
Auto-reverse, fire door to house, outlets
The auto-reverse mechanism is tested by placing a 2x4 flat on the ground under the door. The door must reverse upon contact. Photo-eye sensors are also tested by interrupting the beam. Failure to reverse is a safety hazard, particularly for children.
The door between an attached garage and the home must be self-closing, self-latching, and fire-rated (typically 20-minute minimum). A standard hollow-core interior door fails this requirement and is always flagged. Some codes require a step-up from garage floor to the door threshold.
All garage outlets require GFCI protection per modern code. Unprotected outlets in garages are flagged as electrical safety deficiencies. Inspectors operate garage outlets with a circuit tester.
Garage framing, overhead storage, and ceiling condition are assessed. Evidence of vehicle impact on structural members, improper notching, and inadequate header spans over the garage door opening are documented.
How Long Does a Home Inspection Take?
Inspection duration depends heavily on property size, age, and condition. Rushing an inspection is a red flag — a thorough inspector won't cut corners on time.
1,500–2,500 sq ft, post-1980 construction, typical condition.
3,000+ sq ft or pre-1980 construction with original systems, crawlspace, multiple HVAC units.
Plan to attend the full inspection. Most experienced inspectors walk buyers through their findings in real time. You'll leave with a far better understanding of the home than what appears in the written report alone.
What Happens After the Inspection?
InterNACHI and ASHI standards require a written report. Most inspectors deliver a detailed report — often 40–80 pages with photographs, condition ratings, and recommendations — within 12–24 hours of the inspection.
Your real estate agent will help you distinguish between major defects (safety hazards, structural issues, system failures) and minor maintenance items. Not every finding warrants a repair request.
You may request the seller repair specific items before closing, provide a cash credit at closing, or reduce the purchase price. Sellers are not required to agree, but significant defects give you strong negotiating leverage.
If repairs were completed, a re-inspection verifies the work was done properly. This is a reduced-fee visit focused only on previously noted deficiencies — typically $100–$200.
What Home Inspectors Do NOT Check
A standard home inspection is a visual, non-invasive evaluation. Understanding scope limitations helps set the right expectations.
Scuffs, paint condition, minor cracks in drywall, and surface blemishes are not the focus of an inspection.
Inspectors cannot see behind finished surfaces. Hidden mold, pest activity inside walls, and hidden wiring faults may not be detectable.
Areas blocked by personal property are noted as inaccessible. Sellers are not required to move belongings.
Attic floor sheathing and joists beneath thick insulation cannot be fully assessed without disturbing the insulation.
Underground fuel oil tanks, buried sewer laterals, and buried supply lines require specialized testing (sewer scope, tank scan) not included in a standard inspection.
Doorbells, intercoms, speaker wiring, smart home systems, and security systems are outside standard scope.
These concerns require separate specialty inspections beyond the standard scope:
Frequently Asked Questions
Standard inspections do not cover cosmetic defects, areas hidden behind furniture or under insulation, inside walls, buried pipes or underground tanks, or low-voltage systems like doorbells and intercoms. Specialty testing for radon, mold, sewer scope, and asbestos require separate inspections.
Most home inspections take 2–4 hours for an average single-family home (1,500–2,500 sq ft). Larger homes over 3,000 sq ft and older homes (pre-1980) can take 4–6 hours. The inspector needs time at every accessible area — attic, crawlspace, roof, mechanical room, garage, and all living spaces.
You are not required to attend, but it is strongly recommended. Walking through the home with the inspector lets you ask questions in real time, understand the severity of any issues, and learn maintenance tips specific to that property. Most inspectors encourage buyer attendance.
A problem-free inspection is rare — inspectors typically find 20–50 items worth noting. After receiving the written report, you have several options: request the seller repair specific items before closing, negotiate a price reduction, ask for a closing credit, or in cases of major defects, walk away from the deal. Your real estate agent will guide the negotiation process.
The most frequently cited issues include improper grading and drainage, roof defects (missing or damaged shingles, worn flashing), electrical safety hazards (ungrounded outlets, double-tapped breakers), HVAC systems past expected service life, plumbing leaks, inadequate attic insulation and ventilation, and moisture intrusion in basements or crawlspaces.