A common source of frustration after closing is discovering something the home inspector “missed” — only to find out later that the item in question was explicitly outside the scope of a standard home inspection. Understanding what home inspectors are and aren’t required to examine is not fine print — it’s essential knowledge for any buyer who wants to make genuinely informed decisions about additional due diligence.
What a Standard Home Inspection Covers
A standard home inspection, governed by the Standards of Practice of organizations like InterNACHI (which Russ Motyko at Trusted Home Inspections follows), covers the readily accessible and visually observable components of the following systems:
- Roofing (visible roof surface, gutters, downspouts, visible flashing)
- Exterior (siding, trim, windows, doors, grading, decks, walkways)
- Foundation and structure (visible framing, foundation walls, floor structure)
- Electrical (panel, visible wiring, outlets, switches, fixtures)
- Plumbing (supply, drain, waste, water heater, fixtures)
- HVAC (heating system, cooling system, visible ducting)
- Insulation and ventilation (attic, crawl space)
- Interior (walls, ceilings, floors, stairs, doors, windows)
The key phrase is “readily accessible and visually observable.” A home inspection is a non-invasive, non-destructive examination. Inspectors do not cut into walls, excavate soil, or disassemble systems to look inside them.
What Home Inspectors Cannot Inspect
Sewer laterals and underground plumbing. The home inspector can verify whether drains flow and whether visible drain pipes appear functional, but cannot evaluate the sewer lateral — the underground pipe running from the house to the city main. In Portland, sewer lateral conditions are one of the most significant hidden deficiencies in older homes. Cast iron and clay tile sewer lines are common in pre-1970s homes and are subject to root intrusion, offset joints, and collapse. A sewer scope inspection — a separate service using a camera threaded through the clean-out — is strongly recommended for any home built before 1980. This is not included in a standard home inspection and must be scheduled separately.
Buried oil tanks. Many Portland area homes heated with oil before natural gas became dominant have buried oil storage tanks on the property. These tanks are not visible and cannot be detected during a standard inspection. If the home has or had oil heat, or if the listing discloses an old oil tank, a separate oil tank sweep (typically using a metal detector and magnetometer) is warranted. Buried tank remediation costs can be substantial — $5,000 to $30,000+ depending on whether there has been a leak and soil contamination.
Hazardous materials: asbestos and lead paint. As discussed in our articles on asbestos in Portland homes and lead paint, home inspectors cannot identify these materials. They can note suspect materials and recommend testing, but laboratory analysis is required for confirmation. Separate certified testing is available from Oregon DEQ-licensed professionals.
Radon. Radon testing is a separate service. While some inspectors offer radon testing as an add-on, it is not part of the standard visual inspection. Given that approximately 1 in 4 Portland area homes tests above the EPA action level for radon, this is a high-value add-on for any purchase. See our article on elevated radon levels in Portland area homes.
Mold testing. A home inspector can identify visible mold growth and moisture conditions that promote mold development, but air quality testing and surface sampling for mold identification require a separate industrial hygienist or mold testing specialist. The inspection report will recommend professional mold assessment when suspect growth is found.
Chimneys and fireplaces (internal flue inspection). A standard inspection covers the visible exterior and accessible interior components of fireplaces and chimneys — damper operation, firebox condition, visible flue liner at the opening. It does not include a Level 2 chimney inspection with a camera to evaluate the full internal flue condition. Homes with wood-burning fireplaces and chimneys, particularly older brick chimneys, should have a certified chimney sweep conduct a Level 2 inspection before using the fireplace.
Low-voltage and smart home systems. Security systems, smart home automation, irrigation system electronics, and similar low-voltage systems are generally outside the scope of a standard home inspection. Alarm systems in particular are not tested — testing requires knowledge of alarm codes the inspector does not have.
Swimming pools and hot tubs. Some inspectors include basic pool and spa inspection; many don’t. If the property has a pool or hot tub, confirm explicitly whether it is included in the scope of inspection, and consider a specialist pool inspection for anything beyond basic visual observation.
Wells and septic systems. Properties with private wells or septic systems require separate specialist inspection. Well water testing, pump testing, and septic system inspection (including tank pumping and distribution system evaluation) are distinct services. In the Portland metro area, properties in unincorporated areas of Clackamas, Washington, and Clark counties commonly have private water or septic systems.
Areas that are inaccessible or unsafe to enter. If a crawl space has standing water, insufficient clearance, or hazardous conditions, or if an attic is inaccessible, the inspection report will note the limitation. Inaccessible areas are not inspected — period. This is a legitimate limitation and should prompt the buyer to ask the seller to make the area accessible or engage a specialist.
Systems that cannot be operated safely. If a furnace won’t light, the HVAC system is turned off at the main, or a safety switch prevents operation, the inspector notes this as untested. An HVAC system that couldn’t be operated during the inspection is a significant unknown that should be addressed before closing.
Why Thermal Imaging Extends the Inspection’s Reach
While there are genuine limits to what a visual inspection can reveal, thermal imaging — included on every Trusted Home Inspections inspection at no extra charge — adds meaningful additional detection. Infrared scanning can reveal moisture in wall cavities, insulation deficiencies, electrical hot spots, and heat loss patterns that are invisible to the naked eye. It doesn’t eliminate the limits described above, but it does reduce them.
Building Your Full Due Diligence Team
For most Portland area home purchases, a comprehensive due diligence strategy includes:
- Standard home inspection (with thermal imaging)
- Sewer scope inspection (strongly recommended for homes built before 1980)
- Radon test
- Lead paint testing if home was built before 1978 and children will be present
- Oil tank sweep if home has or had oil heat
- Level 2 chimney inspection if home has wood-burning fireplace or older chimney
Not every purchase needs every item on this list. But understanding what the standard inspection doesn’t cover lets you make informed choices about which additional services are warranted for your specific property.
Ready to schedule? Book your inspection online or contact us. See also: How to Read a Home Inspection Report | What to Expect During a Home Inspection
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