Long-form guide · 11-minute read
Strata inter-unit leak. Find the source. Protect the recovery.
When water shows up in one unit from a leak somewhere above, the most important question isn't 'how do we fix it' — it's 'who's responsible'. We locate the source unit precisely, document common-property vs. unit-owner responsibility, and produce subrogation evidence packages that protect the strata's insurance recovery position.
What is strata inter-unit leak detection?
An inter-unit leak is the most common — and most disputed — type of water damage in BC stratas. Water shows up on one unit's ceiling, but the actual leak is in a unit on the floor above, in a riser inside the wall cavity, in common-property plumbing, or in a horizontal main between floors. Figuring out exactly where matters enormously for insurance, repair scope, and chargeback authority.
BC's Strata Property Act draws sharp lines between common property (the strata's responsibility), limited common property (assigned exclusive use but often shared repair burden), and individual unit interiors (the owner's responsibility). The line determines who pays the deductible, whether subrogation can be pursued, and whether the strata can charge back the repair cost.
Professional inter-unit leak detection identifies the source unit and floor, locates the leak within the unit (or on common property), and produces documentation formatted for the strata's insurance adjuster and for any subrogation action against the at-fault party. This is fundamentally different from residential leak detection — the report has to do legal work, not just diagnostic work.
When you need strata inter-unit leak detection
If you're seeing any of these signs, professional detection is warranted:
- Ceiling stain in one unit with no visible source in that unit
- Wet patches on shared wall between two units
- Water dripping from light fixture or sprinkler head
- Strata-wide pressure drop or unusual common-area meter reading
- Recurring damage at the same location across months (chronic source)
- Mold or moisture detected behind drywall in unit shared with another above
- Adjuster requesting source identification before approving claim
- Pre-AGM building survey identifying suspected leak patterns
Early source identification = lower deductible at renewal
BC strata insurance deductibles have multiplied since 2019. Each claim that gets paid out raises the deductible at renewal — sometimes by tens of thousands. Locating the source quickly and pursuing subrogation against the at-fault party (negligent owner, faulty contractor) keeps claims off the strata's loss history. Prevention surveys (annual leak audits) keep claims from happening at all.
How we detect it
- 1
Council or PM contact
Strata council or property manager calls — describes the damage location, unit numbers, and recent history. We schedule access to all potentially affected units.
- 2
Visual inspection + history review
Walk-through of damaged unit and units above. Review any prior claim history, depreciation report findings, and known common-property issues.
- 3
Thermal + moisture survey
Thermal imaging across ceilings, walls, and floors in all suspect units. Pin-type moisture meters confirm wet zones. This narrows the source to a unit and a room.
- 4
Acoustic + tracer where needed
If the leak is active and pressurised, acoustic correlation triangulates it. For intermittent leaks (auto-fill systems, irrigation), we may install temporary monitoring or use tracer gas.
- 5
Adjudicate common vs. unit
We map the located leak against the building plans and the Strata Property Act framework to identify whether it's common property, limited common property, or unit-owner responsibility.
- 6
Adjuster + subrogation report
Written report formatted for insurance adjuster: thermal imagery, moisture maps, acoustic data, plan-view location, responsibility opinion, and chain-of-custody documentation suitable for subrogation if needed.
Detection technologies we use
Thermal Imaging (FLIR)
First-pass survey across multiple units to identify moisture patterns. Non-invasive — no disruption to tenants.
Learn moreAcoustic Correlation
Triangulates pressurised line leaks in risers and horizontal mains. Critical for high-rise riser leaks that span 30+ floors.
Learn morePin Moisture Meter
Confirms wet drywall and framing — quantifies moisture content for the adjuster's report.
Tracer Gas
For slow or intermittent leaks where acoustic isn't decisive. Identifies pinhole copper leaks in riser stacks and horizontal mains.
Learn moreCommon scenarios
380-unit high-rise
Ceiling damage on 22nd floor. Thermal + moisture survey of units 22, 23, 24 identified source in unit 24 — failed dishwasher supply hose. Repair scoped before insurance was filed. Strata's deductible never came into play.
110-unit mid-rise (parkade)
Repeat parkade leak — 7 years, three failed repairs. Combined GPR + thermal traced the source to a podium drain mis-graded since original construction. One targeted repair ended a 7-year claim cycle.
38-unit townhouse strata
Underground common-property water main leak located behind units 7–9. Acoustic correlation pinpointed the leak; strata recovered the prior quarter's excess water charges from the municipal leak adjustment program.
Typical pricing
Typical range. Final price quoted on the free phone consult.
- Strata inter-unit detection is priced by building size and number of units to access.
- Standard residential inter-unit (3–5 units, 1 source) typically $600–$1,200.
- Multi-floor surveys (high-rise, multiple suspected sources) typically $1,500–$2,500.
- Property managers and stratas with annual programs receive portfolio pricing.
Frequently asked questions
Why does the source unit matter so much for inter-unit leaks?
Because the source determines who pays. If the leak is in the upstairs unit (e.g. failed appliance hose), it's the owner's responsibility — often subrogated to the owner's insurance. If it's in common property (riser, common horizontal main), it's the strata's responsibility, paid from the strata's policy. The deductible may be very different in each case.
Can you work with our property manager?
Yes — property managers are our most common point of contact. We integrate into your workflow: single point of contact, simple invoicing, and reports formatted for distribution at AGM/SGM. We're familiar with FirstService, Crossroads, Rancho, Stratawest, AWM-Alliance, Pacific Quorum, Bayside, Korecki, and the other major BC PM firms.
Does the Strata Property Act apply to your report?
Yes — our reports are written with the SPA framework in mind. We distinguish common property from limited common property from unit interior, and we identify the responsibility line explicitly. This is critical for chargeback authority and for any cost-recovery action.
How fast can you respond to an active inter-unit leak?
Same-day response is often available for active loss situations within our hours (Mon–Sat 8am–6pm Pacific). For ongoing damage, the priority is shutting off the source — call us and we'll guide the council/PM through emergency isolation while we mobilise.
Can your report be used for insurance subrogation?
Yes. We deliver evidence packages designed for subrogation — chain-of-custody documentation, equipment manifests, thermal imagery with timestamps, moisture maps, and findings narratives that hold up to opposing-expert review. BFL, Wawanesa, Aviva, Intact, Co-operators, Northbridge all accept our reports.
Do you provide annual leak survey programs for stratas?
Yes — and they're our most cost-effective service. Annual preventive surveys catch developing leaks before they become claims. Most stratas running annual programs see their deductible hold steady (or drop) at renewal.
What if the upstairs owner won't grant access?
Under the Strata Property Act, the strata corporation has access rights for inspection and emergency. Our reports document the necessity of access for the council/PM to enforce. We typically secure cooperation when access is requested formally with the report in hand.
Can you support our depreciation report?
Yes. We work with all major BC depreciation report providers (Normac, RDH, RJC, Morrison Hershfield) — supplying leak-history and current building-condition data for the 10-year and 5-year updates required under the SPA.
How long does an inter-unit investigation take?
Typical 2-floor, 4-unit investigation is 2–3 hours on-site. High-rise multi-floor surveys can be a full day. Written report delivered within 24 hours of on-site work.
What if you can't determine the source?
Rare but possible. If thermal, acoustic, and tracer gas all fail to locate the source, the next step is targeted access (small inspection holes in non-finished areas of suspect units). We always exhaust non-invasive options first.
Does your report help with Form B / Form K disclosure?
Yes. Buyer's lawyers increasingly ask for leak-history certifications during strata sales. We provide formal certifications that attach to Form B disclosure packages and protect both the seller and the strata.
Do you offer permanent leak monitoring systems for high-claim buildings?
Yes. For buildings with chronic claims, we install Zonescan-style permanent acoustic monitoring on risers and horizontal mains. Early-warning data drastically reduces claim size and frequency.
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