A multi-unit inspection in Montreal — duplex, triplex, quadruplex or income property — differs significantly from a single-family home inspection. More units mean more shared systems, more components to document and a different planning horizon for the owner-investor or property manager. This guide explains the particularities of the Montreal plex, the systems verified, the cost, duration and how the report supports a buying decision or work planning.
Why a plex demands a different inspection
A multi-unit building combines several dwellings under one envelope with shared mechanical and structural systems. The inspection must handle access to each unit (tenants in place or not), the presence of common areas (stairwells, basement, balconies), and shared vertical components (plumbing stacks, ventilation, electrical).
For a buyer-investor, the report serves to evaluate short, medium and long-term work — a key input to build a realistic 5-10 year financial model.
Duplex, triplex and 4+ units: what changes with size
The more units, the more complex the inspection:
- Duplex (2 units) — often owner-occupied below, tenant above; roof, foundation and drainage relatively simple.
- Triplex (3 units) — Montreal's typical exterior staircases, multi-floor balconies, vertical plumbing serving 3 stacked kitchens/bathrooms.
- Quadruplex and 4-unit plex — often a habitable or partially habitable basement, adding humidity and ventilation concerns.
- 5+ unit buildings — fall under commercial scope; see our commercial inspection.
Systems verified in a multi-unit
A multi-unit inspection documents the apparent components of:
- Roofing — Montreal plexes frequently have flat roofs; see our flat roofs guide.
- Foundation and structure — often stone foundations on century-old plexes, cracks, movement indicators (see foundation cracks).
- Vertically-shared plumbing — waste stacks, main drains, galvanized or cast iron drains by age (see plumbing guide).
- Perimeter drainage — french drain, semi-buried basement, infiltration indicators (see french drain guide).
- Multi-panel electrical — one panel per unit plus a common-area panel; capacity, wiring types, aluminum or old fuses.
- Apparent acoustic and fire separation — observable only at accessible locations; visible-indicator documentation only.
- Ventilation — per unit, bathroom fan state, hoods, air exchangers.
- Envelope and exterior stairs — balconies, railings, typical spiral stairs, apparent flashings, windows.
Particularities of Montreal plexes
Montreal's multi-unit stock has its own characteristics:
- Century-old plexes — stone foundations, partially-replaced plumbing, stage-modernized electrical, sometimes-retrofitted ventilation.
- Balconies and exterior staircases — Montreal's iconic feature; concrete state, railings, anchors, ongoing monitoring required.
- Semi-buried basements — often used as dwelling; chronic humidity concerns, limited ventilation, aging perimeter drainage.
- Interior common stairwells — less-ventilated, finishes added over time, humidity-indicator monitoring.
- Stacked kitchens and bathrooms — vertical superposition makes humidity transfers or leaks more visible on a lower floor.
How much a multi-unit inspection costs
Multi-unit rates in Montreal are custom-quoted based on unit count, building age and access. As an indication, a duplex typically starts at $1,100-1,350+tax, a triplex at $1,350-1,600+tax, a quadruplex at $1,600-1,900+tax.
A multi-unit inspection typically demands more on-site time and a more substantial report than a single-family inspection.
How long the inspection takes
A multi-unit inspection generally takes 4 to 6 hours on site for 2-4 units, and more for larger buildings or complex common areas. The complete report is delivered within 24-48 hours*.
To optimize logistics, tenant-unit access must be planned in advance with appropriate notice.
What the report documents for the investor
For a buyer-investor or property manager, the report serves to:
- Quantify short-term work (safety, infiltration, apparent code matters).
- Document components at end of useful life (roofing, windows, balconies) with timeline.
- Identify indicators justifying specialized verification (drain camera, structural assessment, plumber).
- Support price negotiation or renovation-fund planning.
When to request specialized verification
Based on documented indicators, the report may recommend:
- French drain camera inspection by a plumber — when infiltration indicators or an aging drain are documented.
- Structural engineer — for evolving cracks, movement indicators, slab uplift, deteriorated concrete balconies (see masonry and lintels).
- Roofer — flat roof at end of useful life or with recent infiltration indicators.
- Plumber (drain camera) — cast iron waste stacks or galvanized plumbing with end-of-life indicators.
- Air-quality specialist firm — extensive mold signs or chronic humidity documented.
How to prepare as owner or investor
To optimize the inspection:
- Coordinate tenant access with appropriate notice and time windows.
- Prepare documents: leases, work invoices, prior inspection reports, seller's declaration.
- Prepare strategic questions: work horizon, possible renovation financing, tenancy context.
- Block a half-day to be present at the end and do the verbal review.
For a tight deadline, see our pre-purchase inspection and our urgent inspection.