What you bought, in one sentence
A home inspector performs a visual, non-invasive examination of the readily accessible systems and components of a house, operating the normal operating controls and opening readily openable access panels, then writes a report describing what was found and naming what could not be reached. That is the whole product, and the ASHI Standard of Practice puts it in one definition: to inspect is “the process of examining readily accessible systems and components by (1) applying this Standard, and (2) operating normal operating controls, and (3) opening readily openable access panels.”
Nearly every disappointment with an inspection traces to a mismatch between what the buyer expected on the day and what that sentence actually required. The inspection is bounded, the boundary is published, and reading it beforehand costs ten minutes. What follows is where the boundary sits and what happens when the house will not let the inspector reach something.
Four words do all the boundary work
Readily accessible. A defined term, and the definitions differ. ASHI and the Illinois rules exclude anything requiring the inspector to move personal property, dismantle, use destructive measures or take an action likely to risk persons or property. Massachusetts, at 266 CMR 2.00, adds a clause the others do not: anything requiring the inspector “to resort to portable ladders.” That is materially narrower, and it reaches the roof, the gutters, the eaves and a high attic hatch.
Visual and non-invasive. Nothing is opened up, taken apart or cut into, and the inspector does not move your belongings. Observable evidence — a stain, a patch, a repainted band at the base of a wall — is reportable, and is usually what prompts a recommendation for somebody whose work is invasive.
Not technically exhaustive. Both national standards use that exact phrase, as does the Arizona board. The inspection establishes the condition of what could be seen on one day through one set of eyes, and nothing more. A defect found later inside a wall is usually evidence the inspection worked as every standard defines it, rather than evidence it failed.
No prescribed order, and no prescribed length
No standard reviewed for this site prescribes the sequence of the work. The conventional pattern — exterior and roof first while the light is good, then structure, attic and crawlspace, then the mechanical systems under power, then the interior room by room, then appliances, then a verbal walk-through — is practice, not rule.
No standard prescribes a duration either. The figure repeated almost everywhere online, two to three hours, does not come from a statute, a regulation, a federal form, a standard of practice or a government publication.
Here is what was searched and did not contain one: Form HUD-92564-CN; the ASHI Standard of Practice; the InterNACHI Residential Standards of Practice; the TREC REI 7-6 form and its instruction sheet; the Illinois, North Carolina, Ohio, Tennessee, Oregon, Kentucky and Louisiana rules; CPSC publications on home safety and home-structure injuries; NC Cooperative Extension publication FCS-436; and the Massachusetts Division of Occupational Licensure’s consumer fact sheet. The last two are the documents most likely to carry such a figure — a land-grant extension guide for buyers, and a regulator’s consumer page — and both discuss inspections at length and give no duration at all.
One regulatory handle exists. Massachusetts requires every report to “record the on-site Inspection start and finish times,” and Illinois requires the inspection time and the weather as report content. No other state rulebook reviewed requires either. In Massachusetts the duration of your inspection is a documented fact in the report you paid for; everywhere else it is whatever the inspector chooses to note.
The absence is structural. No federal program collects home inspection statistics, and a duration rule would reward presence over findings.
What has to be on and reachable
An inspection is a test of systems under power. A system that is shut down is not inspected: the standards do not require an inspector to energize anything turned off, and mostly treat doing so as a safety matter. This is the largest preventable cause of a partial inspection.
| Needed on the day | What happens without it |
|---|---|
| Electricity on at the meter | Panel, receptacles, switches, AFCI and GFCI devices, the air conditioner, the furnace controls and every appliance go uninspected |
| Gas or propane on, pilots lit | Furnace, water heater, range and gas fireplaces cannot be operated. Relighting pilots is not the inspector’s job |
| Water on | Fixtures cannot be run, drains and the waste and vent system cannot be observed in use, and the water heater cannot be checked under load |
| Clear attic hatch and crawlspace access | Roof structure, insulation, ventilation, under-floor framing and plumbing runs may be excluded. Inaccessible spaces need not be entered |
| Clear access to panel, furnace, water heater | Nothing gets moved. Personal property in front of equipment is an exclusion, not a delay |
| Keys, codes, pets secured | Locked gates, sheds and outbuildings are not inspected. A dog in the yard closes the exterior; a car in the garage closes the garage floor |
On a vacant property — a foreclosure, an estate, a long-empty listing — assume nothing is on and arrange utilities in advance. It is the most common reason an inspection has to be repeated, and a second visit is a second fee. Note too what blocked access does to the clock: it shortens the inspection and produces an exclusion.
An exclusion is a transfer of risk, and the transfer is to you
An inspection stopped by an obstruction is a partial inspection, and the standards do not let that disappear quietly. Massachusetts requires every report to record obstructions and conditions that prevented the inspection, and to indicate which designated components were not inspected. Illinois requires the reasons. Texas gives the inspector a dedicated mark, NI, for present but not inspected. Kentucky requires exclusions listed with specificity. North Carolina polices it: its board’s list of the five most common report compliance failures includes a report that did not state why designated components were not fully inspected.
Now the consequence nobody states plainly. The gap is yours. The inspector discharged their obligation by disclosing it, and no seller owes you a second visit. If the attic was not entered because the hatch was blocked and you close anyway, you bought the attic unseen. Three options follow, all time-sensitive: arrange access and a re-inspection, bring in the specialist the exclusion points to, or accept it knowingly. Doing none of the three is the fourth option, and the one most buyers take by default.
Weather works the same way quietly. Snow or ice means the roof covering was not seen. Cold means the air conditioner could not safely be run. Rain the night before means a dry basement proves less than it looks. Massachusetts and Illinois require the weather in the report for that reason. Elsewhere, ask.
What an inspector may not determine
Four determinations are outside the scope almost everywhere, and an inspector who supplies one is working outside the standard that governs them rather than above it.
Code compliance. Texas rules do not require it, and the Commission’s guidance states that it does not require inspection to any of the various building codes; ASHI, InterNACHI and the Arizona board exclude it too. Codes are adopted jurisdiction by jurisdiction and applied as of the date of permit, so compliance is a records question rather than a visual one.
Engineering, adequacy and capacity. The hard line falls at the word adequacy. An inspector must report indications of foundation movement, active water penetration and wood in contact with soil, and may not determine foundation adequacy, identify joist sizing or provide any engineering or architectural service. The same wall stands around causation, which puts the question every buyer asks about a crack outside the scope of the person in front of it.
Concealed and latent conditions. Outside every standard reviewed. Texas: anything buried, hidden, latent or concealed.
Remaining useful life. ASHI excludes “the age, life expectancy or remaining useful life of systems and components”; InterNACHI excludes service life expectancy; Texas and Arizona exclude it by rule. One live conflict is worth knowing before the day. Form HUD-92564-CN, the notice lenders put in front of FHA borrowers, tells buyers an inspector will “estimate the remaining useful life of the major systems, equipment, structure, and finishes” — a service essentially every standard of practice excludes. A buyer who reads the form and then receives a report declining to age the furnace has been set up for a complaint that is nobody’s fault.
Environmental conditions — radon, asbestos, lead paint, mold, air and water quality, pests — are excluded almost everywhere and ordered as named services before the inspection, not raised as questions during it.
Attending: well advised, and barely codified
Attend if you can. The surprising part is how thin the institutional backing is. Two documents recommend it, neither from the inspection industry: the Massachusetts Division of Occupational Licensure’s consumer fact sheet, which says “while not necessary, it is recommended that the buyer be present for the inspection,” and NC Cooperative Extension publication FCS-436, which says “be there when the inspection is done. Follow him or her around. Ask questions.”
That is the entire record. Neither the ASHI standard nor any of the ten state standards of practice reviewed for this site contains a provision on who may attend. The question half of all buyers ask is, as a matter of regulation, not addressed, which makes attendance a term of your agreement rather than a right.
Arrive for the last part, not the beginning: the early work is where interruption costs most and a client sees least. Operate nothing, bring nobody, and leave the negotiating until you have read the document. What attending gets you that the report cannot is location knowledge — the main water and fuel shut-offs, which breaker feeds the garage, where the crawlspace hatch is. None of that is a defect, so none of it is required report content.
The visit is not the inspection
If you are asking how long an inspection takes because you are planning around a contingency deadline, you are measuring the wrong thing. The deliverable is the report, and the gap between the inspector leaving and the document arriving is often longer than the visit. Oregon says so outright: a home inspection “shall be deemed completed when the initial written inspection report is delivered.”
So stop using duration as a screening question. It invites an answer calibrated to what you want to hear and tells you nothing about scope. Ask instead what the inspection includes, what it excludes, which standard of practice the inspector works to, and what happens if a system cannot be reached. Ask for the start and finish times in writing wherever you live — Massachusetts requires them, and nothing stops you asking in the other forty-nine states. Then judge the result by the report rather than the clock.
Where to go next: the procedural walk-through of the day, why no primary source states a duration, whether and when to attend, and the scope boundary in full. Before the day, our guide to what a checklist can and cannot record covers the questions worth carrying. Afterwards, our guide to why there is no national home inspection report explains what governs the document you receive.
Frequently Asked Questions
What happens during a home inspection?
A visual, non-invasive examination of the readily accessible systems and components, with the normal operating controls operated and readily openable access panels opened. The inspector switches systems on and watches them run, runs fixtures and drains them, opens the electrical panel cover, enters the attic and crawlspace where accessible, views or walks the roof, and then writes a report naming both the findings and everything that could not be reached.
How long does a home inspection take?
No primary source states a duration. The national standards, the federal buyer notice, CPSC publications, a land-grant extension guide, a state regulator's consumer fact sheet and nine state rulebooks were all searched and none gives a figure. The familiar two-to-three-hour range is trade custom repeated until it reads like a measurement. Massachusetts is the one state that produces a documented answer, by requiring every report to record the on-site start and finish times.
Do the utilities need to be on?
Yes. A system that is shut down is not inspected, and inspectors are not required to energize anything that has been turned off. Without power, the panel, receptacles, AFCI and GFCI devices, the air conditioner and the appliances go uninspected; without gas and lit pilots, the furnace and water heater do; without water, no fixture or drain can be observed in use. On a vacant property this is the single most common cause of a repeat visit.
Should I attend the home inspection?
Yes if you can, though the institutional support for that advice is two documents and no standard of practice at all. Massachusetts' consumer fact sheet recommends the buyer be present; NC Extension publication FCS-436 advises following the inspector and asking questions. No reviewed standard addresses attendance, so it is a term of your agreement. Arrive for the last part rather than the start, and settle it when you book.
Does the inspector have to walk on the roof or enter the attic?
No. InterNACHI's standard states an inspector is not required to walk on any roof surface, and inaccessible attics and crawlspaces need not be entered and debris need not be moved. Massachusetts goes further and excludes anything requiring a portable ladder from its definition of readily accessible. What you are entitled to know is which method was used, because that determines how much was actually seen.
What happens if the inspector cannot reach something?
It becomes an exclusion and the exclusion is written down. Massachusetts requires obstructions and conditions that prevented the inspection to be recorded, Illinois requires the reasons, Texas marks it NI, and Kentucky requires exclusions listed with specificity. The inspection becomes a partial inspection, and the risk in that gap transfers to you unless you arrange access, bring in a specialist, or decide knowingly to accept it.
Can the inspector tell me whether the house is up to code?
No. Texas rules do not require inspectors to determine code compliance and the Commission's guidance says it does not require inspection to any of the various building codes; ASHI, InterNACHI and the Arizona board all exclude it. Codes are adopted locally and applied as of the date of permit, so a house built correctly under an earlier edition is lawfully existing rather than non-compliant. Compliance is a records question.
Is the inspection finished when the inspector leaves?
Not in Oregon, whose rules provide that “a home inspection shall be deemed completed when the initial written inspection report is delivered.” That definition is written for Oregon's own standards rather than for your purchase contract, but it is the clearest statement in any reviewed document that the deliverable is the report rather than the visit — and it is the right way to think about any deadline keyed to completion of the inspection.