Home Inspector Standards of Practice: Scope, Reports, and Ethics

Home inspector standards of practice define the minimum work a residential home inspector must perform: a non-invasive, visual examination of readily accessible areas across a home’s major systems, resulting in a written report that identifies material defects observed on the day of the inspection. The two organizations whose rules govern almost every inspection in the United States are the American Society of Home Inspectors (ASHI) and the International Association of Certified Home Inspectors (InterNACHI). Their standards overlap heavily, and understanding where they draw the line between what an inspector must do and what sits outside the job is what keeps expectations realistic on both sides of a sale.

Who Writes the Rules

ASHI and InterNACHI each publish a Standard of Practice that most inspectors follow by contract, by license, or both. InterNACHI defines a home inspection as “a non-invasive, visual examination of the accessible areas of a residential property, performed for a fee, which is designed to identify defects within specific systems and components defined by these Standards that are both observed and deemed material by the inspector.”¹ ASHI’s standard uses similar framing with its own definitions and reporting obligations.²

Roughly 35 states require inspectors to hold a license, and most of those states reference ASHI, InterNACHI, or a close adaptation as the regulatory baseline. Even where licensing is not mandatory, inspection contracts typically incorporate one of the two standards by reference. When a dispute reaches a courtroom or a licensing board, that standard becomes the yardstick for whether the inspector met the duty of care.

What “Readily Accessible” and “Visual” Really Mean

“Readily accessible” is narrower than most buyers assume. ASHI defines it as areas available for visual inspection without moving personal property, without dismantling anything, without risk to the inspector or anyone else, and without risk of damage to the property.³ The inspector will not move furniture, lift carpet, remove ceiling tiles, or climb over stored belongings in a garage to reach a panel. If something is blocked, it does not get inspected, and the report should say why.

The visual limitation rules out destructive testing of any kind. If a defect is hidden behind drywall or under flooring, the inspector cannot drill, cut, or pry to find it. The assessment captures the property’s visible condition during the hours the inspector is on-site. It does not predict future failures, catch intermittent problems that were not active during the visit, or uncover latent defects concealed by finishes. Case law generally supports this boundary: an inspector is not liable for a leak behind a finished basement wall because that area was not accessible without damaging the home.

Representative Sampling

Inspectors do not test every outlet, window, or fixture. Both major standards use a “representative number,” which ASHI defines as one component per room for similar interior items like windows and electrical receptacles, and one component on each side of the building for similar exterior items.² A house with 80 outlets might see eight or ten tested. A defective outlet in a room where a different outlet was tested can go undetected and still fall within the standard. This single rule accounts for a large share of buyer frustration after closing.

Normal Operating Controls Only

When testing systems, the inspector uses the controls a homeowner would use day to day: flipping a thermostat to confirm heating and cooling respond, turning on faucets, flushing toilets, pressing GFCI test buttons.¹ The inspector will not bypass a safety switch, manually ignite a pilot light, or activate a system that was shut down at the time of the visit. A furnace that is off with no obvious way to start it from a standard thermostat gets noted as “not operated” rather than forced into service.

Systems the Inspector Must Evaluate

ASHI and InterNACHI require inspection of the same core systems, organized slightly differently between the two. A standard inspection covers:

Roof covering, gutters, downspouts, vents, flashing, skylights, and chimney components, with visible signs of active leaks reported. Many inspectors evaluate the roof from the ground or eaves rather than walking on steep or fragile surfaces.
Exterior wall cladding (siding, brick, stucco), trim, eaves, soffits, fascia, a representative number of windows and all exterior doors, walkways, driveways, decks, porches, railings, and grading around the foundation.¹
Visible foundation walls, slabs, crawlspaces, and basement walls, checked for significant cracking, settlement, or signs of water penetration, along with wood framing in contact with soil and visible structural modifications that raise safety concerns.
Plumbing: the main water shut-off, water heating equipment and its safety controls, interior fixtures and faucets, toilets, drain and waste piping, and sump pumps where present.²
Electrical: service entrance, main disconnect, panelboard, overcurrent protection, grounding and bonding, a representative number of switches and receptacles, GFCI and AFCI protection, and the presence of smoke and carbon monoxide detectors.¹
Heating and cooling systems, each tested through normal thermostat controls, with any that fail to operate or could not be accessed noted in the report.
Fireplace: visible and accessible portions of the firebox, lintel, damper, and cleanout. Joint separation, a non-functional damper, or a missing smoke detector in the same room gets flagged.

Each system is evaluated for safety and basic functionality, not efficiency, capacity, or performance metrics. The inspector is looking for material defects, which InterNACHI defines as issues that “may have a significant, adverse impact on the value of the property, or that pose an unreasonable risk to people.”¹ A component nearing the end of its normal useful life is not automatically a material defect under that definition, although inspectors often note it anyway.

What Falls Outside the Scope

The exclusion list is longer than most buyers expect. InterNACHI’s standards explicitly take the following off the inspector’s plate:⁴

Environmental hazards, including asbestos, lead paint, radon, mold, toxic drywall, electromagnetic fields, and air quality. These require specialized certification and lab testing beyond a visual walkthrough.²
Underground systems: septic tanks, wells, buried fuel storage tanks, and underground irrigation lines.²
Life expectancy and efficiency assessments. The inspector will not estimate how many years a roof has left or rate HVAC energy efficiency, and capacity and BTU output are excluded.⁴
Repair cost estimates. Most standards explicitly prohibit the inspector from estimating what a fix will cost. For a dollar figure, you need a contractor or specialist.
Code compliance. An inspection is not a code inspection. The inspector identifies defects, not code violations, and will not determine whether the house meets current building codes.
Cosmetic conditions. Paint, wallpaper, carpeting, and other finish materials are ignored unless they point to something structural.
Pests. Evidence of rodents, insects, bats, and other pests sits outside the standard scope, though many inspectors offer a separate wood-destroying organism inspection as an add-on.

Advanced Tools Are Not Required

Thermal imaging cameras, drones, moisture meters, and gas detectors are not required under either ASHI or InterNACHI standards.⁴ Some inspectors use them voluntarily, and a thermal camera can catch moisture intrusion or insulation gaps the naked eye misses. An inspector who does not bring a drone is not cutting corners under the standards. If you want thermal imaging or a drone-based roof survey, ask in advance and expect an additional charge.

The Written Report

Every inspection produces a written report. ASHI’s standard requires the report to identify every system and component the inspector examined, note those that are “not functioning properly, significantly deficient, unsafe, or near the end of their service lives,” and flag any systems that were present but could not be inspected, along with the reason.² A locked attic hatch or a flooded crawlspace should appear in the report as inaccessible. Documenting what could not be inspected protects both you and the inspector.

The report is not a warranty, a guarantee of future performance, or an insurance policy on the home. It is a snapshot of what one professional observed on one day. Most inspection contracts make this distinction explicit, and misunderstanding it produces more disputes than almost anything else in the process.

Why the Report Will Not Include Repair Costs

Buyers often ask inspectors to price out repairs, and most will decline. The major standards discourage or prohibit cost estimates because the liability exposure is real. If an inspector says a roof replacement will cost $8,000 and the actual bill comes to $15,000, the client may try to hold the inspector responsible for the difference. The better path is to take the report to a qualified contractor for pricing. Some inspection companies attach third-party cost-estimating tools alongside their reports, but those estimates come from the tool provider, not the inspector.

Liability Limits and Ethics Rules

Most inspection contracts include a limitation of liability clause. InterNACHI’s standard pre-inspection agreement caps liability at 1.5 times the inspection fee, so a $400 inspection limits recovery to $600 regardless of how expensive a missed defect turns out to be. These clauses are generally enforceable under freedom-of-contract principles, with two exceptions: courts will not enforce them against claims of gross negligence, and a handful of states prohibit them outright.⁵ Inspectors also carry two kinds of insurance: general liability for physical harm caused during the inspection, and errors and omissions for claims arising from the report itself. Neither covers items outside the standard of practice.

Both organizations impose ethics rules designed to keep inspectors independent. ASHI’s Code of Ethics prohibits inspectors from repairing, replacing, or upgrading any system covered by the standards for one year after the inspection.⁶ That rule removes the obvious temptation to exaggerate defects to generate repair work. Inspectors also cannot accept referral fees from contractors they recommend, inspect a property in which they have a financial interest, or work under contingent arrangements where their compensation depends on the outcome of the sale.⁷ An inspector who also offers to fix the problems they found is a red flag worth taking seriously.

1
InterNACHI. Home Inspection Standards of Practice
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American Society of Home Inspectors. ASHI Standard of Practice
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American Society of Home Inspectors. ASHI Standard of Practice and Rationale
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InterNACHI. Home Inspection Standards of Practice – Limitations, Exceptions and Exclusions
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InterNACHI. The Enforceability of InterNACHI’s Limitation of Liability and Related Provisions in Its Pre-Inspection Agreement
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American Society of Home Inspectors. ASHI Code of Ethics
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American Society of Home Inspectors. ASHI Standard of Practice for Home Inspections and Code of Ethics