Duplex and Multi-Family Home Inspection: What Investors Need to Know
A multi-family inspection is not just a single-family inspection done twice. The scope is larger, the deferred maintenance risk is higher, and the cost of missing a major finding comes directly out of your projected returns.
Why Multi-Family Inspections Are More Complex
A duplex or triplex has the same structural and exterior systems as a comparably sized single-family home -- one roof, one foundation, one exterior -- but multiplied mechanical systems inside. Two or three of everything: furnaces, water heaters, electrical panels, plumbing stacks. Each unit may have been maintained differently, or not maintained at all, depending on the landlord's priorities and the tenants' habits.
The inspection scope must cover both the per-unit systems and the shared building systems. Missing one category means missing half the picture. An investor who sees "roof looks good" in the inspection summary but misses that two of three HVAC units are at end of life has a $15,000 to $20,000 capital expense that wasn't in their underwriting.
What Gets Inspected Per Unit
Each individual unit requires its own evaluation of the following systems. The conditions in one unit tell you nothing reliable about the others.
Each unit should have its own clearly labeled sub-panel or service, with breakers sized appropriately for the unit's load. Check for double-tapped breakers, oversized breakers, and aluminum wiring.
Units often have separate furnaces and AC systems with different ages and maintenance histories. Check age, filter condition, and whether each unit heats and cools adequately. Replacement cost per unit: $4,000 to $12,000.
Confirm each unit has a water heater (or access to a shared system), check age and condition, and verify temperature and pressure relief valves are present and not corroded.
Run multiple fixtures in each unit to check pressure and hot water response. Low pressure in upper-floor units may indicate supply line problems or inadequate main service size.
Multi-family codes often require dedicated bathroom exhaust fans vented to the exterior. Exhaust fans vented to attic spaces create moisture problems that are common and expensive in older multi-family stock.
Each unit must have working smoke detectors per current code, regardless of when the building was built. Landlords must ensure operability. An inspector notes deficiencies but may not test every unit.
Shared Systems: The High-Cost Inspection Targets
Shared systems affect all units simultaneously and represent the largest single repair risks in multi-family properties. These are what differentiate a building in good condition from one with significant deferred capital needs.
A single roof failure affects all tenants and typically costs $8,000 to $25,000 to replace depending on size and material. Inspectors evaluate current condition and estimated remaining life. Get a roofer's estimate if the inspector rates it less than 5 years remaining.
Foundation problems in multi-family buildings are proportionally more expensive to repair because more of the structure is affected. Look for differential settlement between units, which can indicate varied soil conditions under the footprint.
Main water service, shared supply risers, and shared drain stacks all affect every unit. Age of main service line and condition of shut-off valves at each unit are key items.
Common entries, stairs, and walkways are both a liability concern and a maintenance cost. Cracked concrete entries, deteriorated railings, and inadequate lighting are common deferred items.
Paved parking areas crack and deteriorate. Seal coating ($500 to $1,500) and eventual repaving ($5,000 to $15,000) are capital items investors often miss. Check drainage slope and condition.
Shared laundry hookups, boiler rooms, and utility areas often show deferred maintenance and code deficiencies. Check venting, gas connections, and clearances.
Tenant-Occupied Units: Access and What to Look For
When units are occupied, tenants' belongings, furniture, and storage can conceal wall damage, floor conditions, and pest evidence. An inspector cannot move personal property, so some conditions may be genuinely inaccessible. Note what was and was not accessible in writing.
Wear patterns in tenant-occupied units are informative. Heavy water staining around toilets and under sinks indicates chronic plumbing issues that tenants have lived with rather than reported. Patched drywall that doesn't match surrounding texture usually indicates a prior repair for water damage or mold. Stained ceiling tiles are almost always a water intrusion indicator.
- - Confirm all units have been noticed and will be accessible
- - Get the name of any tenant who has formally refused access so you have it in writing
- - Ask whether any unit is currently vacant and whether utilities are on in that unit
- - Ask whether any pest control treatments are active in any unit
- - Get copies of any outstanding code violations, violation notices, or open permits
Using the Inspection to Build a Capital Expenditure Budget
The inspection report is not just a defect list -- it is the primary input for your capital expenditure (CapEx) budget. Every item the inspector rates as "near end of useful life" is a future expense your pro forma must include.
| Component | Expected Life | Replacement Cost (2-unit) |
|---|---|---|
| Roof (asphalt shingle) | 20-30 years | $8,000 – $20,000 |
| Furnace (per unit) | 15-25 years | $2,500 – $5,000 each |
| Central AC (per unit) | 12-20 years | $3,500 – $7,500 each |
| Water heater (per unit) | 8-12 years | $800 – $1,800 each |
| Electrical panels (per unit) | 40-60 years (if not FPE/Zinsco) | $2,000 – $4,500 each |
| Main sewer line | 50-100 years (varies by material) | $3,500 – $12,000 |
A standard multi-family underwriting practice is to budget $100 to $200 per unit per month for CapEx reserves. The inspection report tells you whether the actual reserve needed is at the low or high end -- or whether you need to budget more before year one.
What to Ask the Seller Before Your Inspection
The seller is legally obligated to disclose known defects in most states, but not obligated to volunteer information you do not ask for. Put these requests in writing through your agent before inspection day:
- 1.Maintenance records for the roof, HVAC units, and any plumbing or electrical work in the last five years.
- 2.Age and service history of each HVAC unit -- they often differ by unit and the listing may not disclose.
- 3.Any permits pulled in the last 10 years, and confirmation they were closed and finaled.
- 4.Any outstanding code violations, notices of violation, or open permits from the local municipality.
- 5.Utility bills (electric, gas, water/sewer) for the last 12 months to verify operating expense assumptions.
- 6.Any known history of water intrusion, mold, or pest activity in any unit.
- 7.Whether any unit has been modified from its permitted use (basement unit, attic conversion).
Frequently Asked Questions
A duplex inspection typically costs $500 to $800, compared to $300 to $500 for a single-family home of similar size. Triplexes run $700 to $1,000. Four-unit properties run $900 to $1,400. The increase reflects additional time to inspect each unit's individual systems -- HVAC, electrical panel, plumbing fixtures -- plus shared systems like the roof, foundation, common areas, and exterior. Inspectors in high cost-of-living markets charge more. Always confirm the fee covers all units before booking.
Yes. Most states require landlords to provide tenants reasonable notice (typically 24 to 48 hours) before allowing access for a buyer's inspection. The listing agent should coordinate this in advance. Occupied units sometimes restrict access -- a tenant may refuse or be unavailable -- so confirm access before the inspection day. If a unit cannot be accessed, note it in writing and consider whether to waive, extend, or hold back an escrow amount for that unit's inspection.
Deferred maintenance that has accumulated across multiple units simultaneously. In a single-family home, the owner-occupant usually addresses problems affecting their daily life. In a tenant-occupied multi-family, landlords often defer maintenance on systems tenants don't complain about: the roof, foundation drainage, electrical panels, and HVAC units that are 'still working' but near end of life. The inspection may reveal $30,000 in upcoming capital expenditures that were not visible in the income pro forma.
Ask for maintenance records on the roof, HVAC units, and any plumbing or electrical work in the last five years. Ask the age of each HVAC unit (they often differ by unit). Ask whether any unit has had water intrusion, mold, or pest problems. Ask about any permits pulled in the last 10 years and whether they were closed. Ask whether any unit has been converted from a different use (attic apartment, basement unit) and whether it was permitted. Ask for utility bills for the last 12 months -- landlord-paid utilities inflate operating expenses.
Properties with 1 to 4 units are typically inspected under residential standards by licensed home inspectors. Properties with 5 or more units are classified as commercial real estate and typically require a commercial property inspection (often called a Property Condition Assessment or PCA), which follows ASTM standards and is more formal and expensive. Some buyers of 4-unit properties also commission a PCA for lender or due diligence purposes even though residential standards apply.