A sewer scope is one of the highest-value specialist inspections to add.
A sewer scope is one of the highest-value specialist inspections to add.

Home inspections follow industry standards (ASHI or InterNACHI) that define what an inspector must do and — critically — what they are NOT required to do. A standard home inspection gives you a visual walkthrough of accessible systems. It does NOT include testing for specific hazards, evaluating specialized systems, or providing warranties. For most homes, supplementing the standard inspection with 2-4 targeted specialist evaluations is the single most important due diligence decision a buyer makes.

This guide covers what's in the standard inspection scope, what's not, and which specialist inspections are worth the extra money.

This guide is organized the way the decision actually plays out in practice: what matters, what does not, and the reasoning behind each recommendation. Numbers and ranges reflect 2026 Connecticut, Massachusetts, and New York conditions and pricing.

Quick answer

A standard home inspection covers visible, accessible portions of roof, exterior, structure, electrical, plumbing, HVAC, interior, insulation/ventilation, fireplace, and built-in appliances. It excludes wells, septic systems, sewer lines, pools, pests, mold, radon, lead, asbestos, UST (oil tanks), chimney interior, roof underlayment, inside walls, underground components, and future conditions. Most buyers should add: sewer scope ($150-$450), radon test ($150-$300), WDO/termite inspection ($100-$300), and in many regions either well/septic or oil tank scans. Total cost for a complete diligence package: $700-$2,500 depending on home and region. The most expensive surprise is the specialist inspection you didn't do.

Field context

Northeast residential markets reward preparation more than most national guides convey. Inventory is chronically tight in desirable suburbs, transaction customs vary by state (attorney involvement, P&S structure, review periods, and contingency conventions all differ between CT, MA, and NY), and the housing stock includes a disproportionate share of pre-1940 homes whose inspection findings can derail inadequately-prepared buyers. Buyers and sellers who understand the sequence, the timing, and the standard variations before entering a specific transaction consistently outperform those who learn the process in real time.

Two preparation items matter disproportionately. The first is team assembly: buyer's agent, real estate attorney, inspector, mortgage lender, and insurance agent should be engaged before a specific property is in play, not after. The 10-to-14-day window between offer acceptance and binding contract is not the right time to be interviewing professionals. The second is decision pre-commitment: knowing in advance what offer price, contingency terms, and walk-away conditions feel acceptable. Under bidding-war pressure, homeowners routinely make decisions they would not have made with 48 hours to think; the antidote is to decide in calmer moments and stick to the decision.

Finally, the regional market conditions matter to timing but less than most buyers believe. Over a 7-to-10-year ownership horizon, a carefully-chosen property in a strong location outperforms a poorly-chosen property purchased at a market low. The leverage is in property and location selection, not in timing the market.

What IS in the standard inspection scope

ASHI and InterNACHI standards of practice define these visible and accessible areas:

Exterior

  • Roof surface (if safely accessible)
  • Siding, trim, flashing
  • Windows and doors
  • Exterior paint and caulk condition
  • Decks, porches, steps, railings
  • Grading and drainage at foundation
  • Driveway and walkway condition

Structure

  • Foundation (visible portions)
  • Slab or basement floor
  • Framing (accessible from basement, attic, crawlspace)
  • Walls and floors for visible movement
  • Beam and column visible condition

Electrical

  • Service entry and main panel
  • Visible wiring
  • Outlets and switches (representative sample)
  • Smoke and CO alarm presence
  • Bonding and grounding where visible

Plumbing

  • Water supply pipes (material, visible condition)
  • Drain, waste, vent pipes (visible)
  • Water heater (age, operation, relief valve)
  • Fixtures (functional check)
  • Shutoff valves (operation where safely tested)

HVAC

  • Heating system operation and age
  • Cooling system operation and age
  • Thermostat operation
  • Visible ductwork
  • Return and supply registers

Interior

  • Walls, ceilings, floors for visible defects
  • Doors, windows for operation
  • Stairs and railings for safety
  • Attic access and insulation visible
  • Basement/crawlspace visible conditions

Built-in appliances

  • Dishwasher, disposal, microwave, range, oven — functional check

What is NOT in the standard inspection scope

Underground / subsurface

  • Sewer lateral — the pipe from house to municipal main; scope requires video inspection
  • Septic systems — leach field, tank condition, flow testing
  • Wells — water quality, flow rate, aquifer depth
  • Underground oil tanks (USTs) — presence and condition
  • Drain tile / footing drains — functionality
  • Buried propane tanks — condition

Inside walls, ceilings, floors

  • Wiring runs between outlets
  • Plumbing lines in walls
  • HVAC duct runs within framing cavities
  • Insulation in closed cavities
  • Mold in wall cavities

Environmental

  • Lead paint (separate RRP-certified inspector)
  • Asbestos (separate abatement inspector)
  • Radon (separate test)
  • Mold (separate inspector; industrial hygienist for detailed testing)
  • Water quality testing
  • Soil contamination

Specialized systems

  • Swimming pools and spas (separate pool inspector)
  • Irrigation systems (dedicated inspection)
  • Elevators and lifts
  • Security systems
  • Low-voltage systems (alarms, CCTV)
  • Solar PV (often requires solar-specific inspection)
  • Generators (service inspection)

Pest / biological

  • Wood-Destroying Organisms (WDO) / termites
  • Carpenter ants, other wood-destroying insects
  • Rodent activity (specialty)
  • Insects in general

Inaccessible areas

  • Attics with limited access
  • Crawlspaces below minimum clearance
  • Roofs too steep or weather-affected
  • Areas blocked by storage
  • Finished basements that obscure framing

Chimney interior

  • Flue liner condition
  • Creosote buildup
  • Crown condition inside
  • Cap condition (visible externally only)

Future conditions and lifespan

  • Inspector describes current condition; not guarantees of future performance
  • No warranty on systems, components, or the inspection itself (some inspectors offer buyer-focused warranties; these are separate products)

The specialist inspections worth adding

Sewer scope — almost always worth it ($150-$450)

Video scan of the sewer lateral from house to municipal main. Catches root intrusion, bellies, offsets, and material-specific problems. Critical for homes 30+ years old or with mature trees on the lot. See the sewer line article for detail.

Radon test — always in Zone 1 and 2 ($150-$300)

48-hour continuous monitoring test. Required by some lenders; strongly recommended in all zones. See the radon article.

WDO / termite inspection — always in termite country ($100-$300)

Wood-Destroying Organism inspection with NPMA-33 report. Essential in southern US states; recommended anywhere termites are active. See the WDO article.

Well water testing — for any well water property ($150-$500)

Lab analysis for bacteria, nitrates, metals (including arsenic, lead, uranium depending on region), and basic chemistry. Every well property should test before occupancy.

Septic inspection — for any septic property ($400-$900)

Tank inspection (opening, pumping if due), baffle check, drain field percolation test. Critical for septic properties.

Oil tank (UST) detection — in Northeast/Mid-Atlantic ($250-$1,200)

Tank scan or GPR survey in regions where USTs are common. See the UST article.

Pool / spa inspection — for pool properties ($200-$600)

Pool-specific inspector checks equipment, safety, structural, and electrical.

Specialized structural (if inspection flags) — $400-$1,600

Licensed structural engineer evaluation of any flagged structural concern.

Lead paint risk assessment — pre-1978 homes ($400-$900)

Full XRF scan and risk assessment. See the lead paint article.

Energy audit with blower door — recommended for older homes ($300-$900)

Comprehensive energy performance assessment; informs weatherization and HVAC decisions.

Mold inspection — if visible or suspected ($300-$800)

Separate inspector using air sampling, surface testing, and infrared imaging.

Total diligence package

For a typical older home in the Northeast, a complete diligence package might include:

  • Standard home inspection: $400-$700
  • Sewer scope: $250
  • Radon test: $200
  • WDO inspection: $150
  • Oil tank scan: $400
  • Chimney Level 2: $450

Total: $1,850-$2,150

For a recent-construction home in a dry-climate area:

  • Standard home inspection: $400-$600
  • Sewer scope: $200
  • Radon test: $200

Total: $800-$1,000

Every additional $500 in upfront inspection frequently saves $5,000-$50,000 in post-close surprises. The math strongly favors comprehensive diligence.

Choosing your inspectors

Home inspector

ASHI-certified or InterNACHI-certified. Ask:

  • How long have they been inspecting in your market?
  • Do they offer sample reports?
  • What's their typical report turnaround time?
  • Do they attend the inspection for your questions?

Specialists

Use separate, independent specialists — not recommendations from the home inspector (conflict of interest) or the seller's agent (definite conflict).

Red flags

  • Inspectors who won't attend the inspection with you
  • Reports that are boilerplate without property-specific photos
  • Inspectors who offer to perform repairs (forbidden by most state laws)
  • Unusually fast (under 2 hours) inspections
  • Inspectors without errors & omissions insurance

Scheduling the inspections

Most inspections should occur during your inspection contingency period (typically 7-14 days post-offer).

  • Day 1-2 — Home inspection scheduled
  • Days 2-4 — Home inspection completed; specialists ordered based on findings
  • Days 4-8 — Specialist inspections completed
  • Days 7-14 — Review all reports, negotiate with seller
  • Day 14 deadline — Inspection contingency decision (accept, negotiate, or walk)

Rush everything. Two weeks sounds like a lot, but it disappears fast.

Diligence and documentation

Diligence in a well-run transaction is less about any single tactic and more about consistent execution of a short list of practices. Pre-approval before offer (not pre-qualification). Written offer with clean contingencies rather than a verbal offer with implied terms. Three-to-five-year intent on neighborhood, commute, and school fit, not six-month intent. Inspection with a reputable, licensed inspector whose findings will be credible to the buyer's eventual lender and insurer. Written response to inspection findings — repair requests, credit requests, or escrow arrangements — rather than verbal agreements that become difficult to enforce at closing.

Documentation throughout the transaction creates the record that future diligence depends on. The closing file, the inspection report, the appraisal, the title search, and all written correspondence should be preserved in one place. The homeowner who can produce these documents three, seven, or ten years later has options — for refinancing, for insurance claims, for the eventual resale — that the homeowner with scattered or missing records does not.

Bottom line

The pattern that distinguishes well-executed transactions from difficult ones is consistent across markets: the parties who prepare early, understand the process before entering it, and treat the timeline as a sequence of deliberate steps rather than a series of reactive deadlines end up with better outcomes. That mindset is worth more than any specific tactical maneuver in the transaction itself.

Related Stela Home coverage

How Stela Home helps

Three Stela Home tools work together on this kind of decision:

  • Stela Report — pre-purchase property intelligence with disclosure, condition, and risk flags.
  • Repair Calculator — modeled cost ranges by category and ZIP, calibrated with regional and complexity multipliers.
  • Stela Guides — step-by-step repair walkthroughs reviewed by licensed professionals, with safety callouts and disclosure.

Sources and further reading