ASHI vs InterNACHI Standards of Practice explained

Here is the short answer: the ASHI Standard of Practice and the InterNACHI Standard of Practice cover the same basic ground (structure, roof, plumbing, electrical, heating and cooling) but they are written differently, define terms differently, and draw the exclusion lines in slightly different places. According to an ASHI-reviewed comparison from National Home Inspection Authority, "neither standard requires inspectors to perform invasive or destructive testing," since both are built around a visual, non-invasive inspection. That shared foundation is real, but the fine print underneath it is not identical, and that fine print is what this article walks through.

We already covered ASHI and InterNACHI as membership groups (cost, exams, perks) in our other post on ASHI vs InterNACHI certification. This post is different. It skips the membership dues and exam questions and goes straight into the written rulebooks themselves: what each Standard of Practice tells an inspector to inspect, describe, and report, what each one explicitly leaves out, how each one defines its own words, and how each treats things like roof access and cosmetic flaws.

What is a Standard of Practice, and why does it matter?

A Standard of Practice is a written rulebook. It tells an inspector what a normal, professional inspection must cover, what tools and methods count as "inspecting," and what falls outside the job. Think of it as the fine print behind every inspection report.

Both ASHI and InterNACHI publish their own version. Neither one is a law by itself. Your state license, not your association's rulebook, is what makes an inspection legal. But most working inspectors follow one of these two documents closely, because clients, agents, and even some state boards point to them as the accepted baseline for a "normal" inspection.

What counts as a "home" under each Standard of Practice?

Both documents use almost the same scope, which surprises a lot of new inspectors.

How InterNACHI defines its scope

The InterNACHI Standards of Practice apply to "properties with four or fewer residential units and their attached garages and carports." A residential unit is defined as a space with its own kitchen, sleeping area, and bathroom. Anything bigger, like a five-unit apartment building, falls outside this Standard entirely.

How ASHI defines its scope

The ASHI Standard of Practice uses nearly the same line: it applies to "buildings with four or fewer dwelling units and their attached and detached garages and carports." ASHI also adds a plain warning up front that its inspections are "not technically exhaustive," meaning the inspector is not expected to find every hidden problem, only what a reasonable visual check would turn up.

What must an inspector actually inspect, describe, and report?

Here is where the two documents start to read differently, even though they aim at the same systems.

InterNACHI's three-part structure

InterNACHI breaks nearly every system into three jobs: inspect it, describe it, and report on it if it needs correction. For the roof, that means the inspector must inspect the coverings, gutters, and flashing, describe the roof-covering material, and report anything like an active leak as needing correction. The same three-part pattern repeats for the foundation, electrical panel, plumbing, and heating and cooling system.

ASHI's condition-based language

ASHI leans on a different phrase throughout its document. It asks the inspector to flag anything "not functioning properly, significantly deficient, unsafe, or near the end of its service life," then explain the problem in plain terms if it is not obvious, and recommend correction or further monitoring. ASHI's report also has to name any major system that was present at the property but not inspected, along with the reason why (for example, a locked electrical panel or standing water in a crawl space).

How do the two Standards handle roof and attic access?

This is one of the most practical differences for a working inspector, and it is also one of the biggest myths clients believe.

Ground level, ladder, or eaves only

Neither Standard requires an inspector to climb onto a roof. InterNACHI's language says the inspector shall "inspect from ground level or the eaves" and is "not required to walk on any roof surface." A real estate education resource, Kaplan Real Estate Education's roof safety guide, backs this up directly: "there are no requirements in the standards of practice of the national associations for home inspectors for climbing on the roof," and it lists ground-level binoculars, ladder inspection, and drones as accepted alternatives.

Why this rule exists

Falls are one of the biggest safety risks in the inspection business. Both organizations built their Standards around a visual, non-invasive inspection, and that includes not asking an inspector to risk a fall just to look at shingles up close.

Attic access limits

ASHI spells out hard numbers here: an inspector is not required to enter a crawlspace with less than 24 inches of clearance, or an attic with an access opening smaller than 16 inches by 24 inches. InterNACHI's language is less numeric. It simply says entry is not required where the space is "not readily accessible, or where entry could cause damage or, in the inspector's opinion, pose a safety hazard." Either way, the inspector gets to make a judgment call, but ASHI gives a specific measurement to point to.

What do the glossaries and key definitions say?

Both Standards include a glossary, and the word choices matter more than most people assume.

"Readily accessible," compared

InterNACHI defines "readily accessible" as a system "capable of being safely observed without the removal of obstacles." ASHI's version is nearly a match: available for visual inspection "without requiring moving of personal property, dismantling, destructive measures, or actions that will likely involve risk to persons or property." The two land in the same place: if the inspector has to move furniture, break something, or risk getting hurt, it is not "readily accessible," and it is fair game to skip.

"Material defect" vs "unsafe"

InterNACHI centers its whole document on the term "material defect," defined as an issue that could have "a significant, adverse impact on the value of the property, or that poses an unreasonable risk to people." ASHI splits the idea into separate terms. It defines "unsafe" narrowly, as a condition that poses "a significant risk of serious bodily injury...during normal, day-to-day use," and handles value or performance issues under its broader "not functioning properly" and "significantly deficient" language instead of one catch-all term.

How does each Standard treat cosmetic and aesthetic issues?

Both documents draw a clear line around looks versus function, and both land on almost the same answer: cosmetic issues are not the inspector's job.

InterNACHI states plainly that its inspections "will not deal with aesthetic concerns, or what could be deemed matters of taste, cosmetic defects, etc." and defines a cosmetic defect as an imperfection "which could be corrected, but is not required." ASHI's wording is nearly identical in spirit: inspectors "are not required to identify and to report...cosmetic imperfections that do not significantly affect a component's performance of its intended function." In plain terms, a scuffed baseboard is not a defect. A cracked foundation wall is.

What do both Standards leave out completely?

The exclusion lists are long, and they overlap heavily between the two documents.

Environmental and hazardous conditions

Neither Standard requires testing for mold, asbestos, lead, or radon. This trips up a lot of home buyers who assume a "home inspection" automatically checks the air and water for hazards. As National Radon Program Services explains, "the radon test is generally a separate service and must be requested," which lines up exactly with what both ASHI and InterNACHI say in their own documents: those tests sit outside the base inspection and need a separate request and, often, a separately licensed tester.

Systems, causes, and costs outside scope

Both Standards also agree that an inspector is not required to do several things that clients often assume are included:

• Determine the cause of a problem.
• Estimate the cost to fix it.
• Predict how much longer a system will last.
• Confirm compliance with local building codes.
• Inspect pools, spas, security systems, sprinkler systems, wells, or septic systems, which usually need their own specialist.

The National Association of Realtors' consumer guide to home inspections tells buyers the same thing in plain language: a standard inspection covers "a home's structure, exterior, roof, plumbing, electrical systems, heating and air conditioning, interiors, ventilation and insulation, and fireplaces," while hazard testing is a separate add-on.

What reporting language does each Standard require?

Both documents care a lot about how the final report is worded, not just what gets inspected.

InterNACHI's Standard reminds readers that the inspection "is based on the observations made on the date of the inspection, and not a prediction of future conditions," and that it "will not reveal every issue that exists or ever could exist." ASHI requires its inspectors to explain any deficiency "that is not self-evident" in plain terms, and to list any major system that was present at the home but not inspected, along with the reason. Both rules exist for the same reason: to protect the client from a false sense of certainty, and to protect the inspector from being blamed for a problem that showed up after the walkthrough ended.

Does your state actually require ASHI's or InterNACHI's Standard?

Usually not directly, and this catches new inspectors off guard. Most states write their own Standard of Practice into law, and it often borrows language from both ASHI and InterNACHI without adopting either one word for word. A guide on Texas's licensing Standard of Practice makes the point clearly for that state: "the only SOP that a licensed inspector is legally required to follow is the one codified by TREC," and "neither ASHI's SOP nor InterNACHI's SOP is a Texas regulatory requirement." Membership in either group stays voluntary. If you break your association's Standard, you risk a membership issue. If you break your state's Standard, you risk your license. Always check your own state board's rules first, then treat ASHI or InterNACHI's document as a strong add-on, not a replacement.

How PadInspector helps you follow either Standard of Practice

Whichever Standard of Practice you follow, the paperwork is the same headache: you walk the property, take notes on dozens of items, snap photos of each one, then spend hours turning it all into a clean report before end of day. PadInspector is voice-driven software for iPad, iPhone, and Apple Watch that is built to close that gap. You talk while you walk, and it transcribes your words, attaches photos to the right area of the home, and drafts the full report before you leave the driveway.

It also handles one job that eats hours under either Standard: checking whether something you found is a real code violation worth flagging as needing correction. The PadInspector feature list includes automatic building-code-violation lookup, so instead of digging through a codebook after the walkthrough, you get the reference right when you spot the issue, whether you report it the InterNACHI way or the ASHI way. PadInspector also works fully offline, logs the day's weather for liability protection, and lets office staff pre-fill an inspection from Zillow before you even arrive.

PadInspector is invite-only while the team grows carefully. If you want your reports written faster, no matter which Standard of Practice you follow, request an invite and see how much time comes back to your day.

FAQ: ASHI vs InterNACHI Standards of Practice

Are the ASHI and InterNACHI Standards of Practice legally binding?

No, not by themselves. Both are voluntary professional documents published by membership associations. Your state's own licensing Standard of Practice, where one exists, is the legal requirement. Association Standards add a professional layer on top of that.

Do both Standards require testing for radon, mold, or asbestos?

No. Both explicitly exclude hazard testing from the base inspection. Those tests are separate services that usually need to be requested on their own and, in many states, performed by a separately certified tester.

Can an inspector be required to climb onto a roof under either Standard?

No. Both Standards allow ground-level, eave-level, or ladder inspection of the roof, and neither requires the inspector to physically walk the roof surface. Drones and binoculars are common accepted alternatives.

Do ASHI and InterNACHI define "defect" the same way?

Not exactly. InterNACHI centers its Standard on one broad term, "material defect," covering both value impact and safety risk. ASHI splits the idea into separate terms like "unsafe," "not functioning properly," and "significantly deficient," which cover similar ground through more specific labels.

Do the two Standards apply to the same size of property?

Yes, almost exactly. Both apply to properties with four or fewer residential or dwelling units, plus their attached garages and carports. Larger multifamily buildings fall outside both documents.

Does either Standard require the inspector to estimate repair costs?

No. Both explicitly state that repair cost estimates, remaining service life, and the cause of a defect are outside what an inspector is required to determine. The report identifies the issue; pricing and diagnosis are left to a specialist or contractor.