ventilation (Home Systems)

Ventilation

• What this is: how whole-home mechanical ventilation works in BC — HRV/ERV systems, bathroom and kitchen exhaust, and fresh-air intake — with a focus on coastal BC’s moisture reality. Covers both strata and detached.
• Not: range hoods (see range-hood (Home Systems)); HVAC filters for the furnace (see hvac-filters (Home Systems)); heating systems (see heating-system (Home Systems)); smoke/CO detectors as standalone devices.
• Figures: 2025–26 Metro Vancouver estimates — get your own quotes.

Bottom line

The rule (tripwire)

• If you see condensation on windows regularly, find mould in corners or closets, or smell musty air → your ventilation is failing. These are not cosmetic issues; in coastal BC’s tight modern construction, inadequate ventilation means moisture cannot leave the building and mould follows. Act now — not on the next inspection.
• If your bathroom fan ducts into the attic instead of to the exterior → this is a code violation and a mould risk. Exhaust must terminate outside the building envelope. Under BC Building Code Section 9.32, exhaust duct must vent directly outdoors, insulated to RSI 0.75, with no termination into attic, soffit, or crawl space.¹
• If you have a ducted HRV/ERV → do not turn it off. It must run continuously (except when servicing) to meet BC Building Code ventilation requirements. Running it on low 24/7 costs roughly $3–10/month in electricity.²

Recurring upkeep

• Clean HRV/ERV filters every 3 months — wash them under running water, air-dry, reinstall. This is the entire owner maintenance job for the unit itself. A clogged filter reduces airflow and kills heat-recovery efficiency.³
• Check exterior HRV vent caps every 6 months — clear debris, bird nests, and ice buildup. A blocked intake or exhaust kills the air exchange.
• Run bathroom fans during showers and for 30 minutes afterward — or install a timer/humidistat so you don’t have to remember. This is the cheapest mould prevention in the building.⁴

One-time setup

• Confirm with your strata (if applicable): is the HRV unit inside your strata lot or in common property? New-construction stratas sometimes have shared HRV systems serving multiple units — if yours is shared, the strata maintains it. If the unit is inside your dwelling, maintenance is yours.
• Add a bathroom timer or humidistat if your fan has no automatic shutoff. A $30–$60 timer that runs the fan 30 minutes after occupancy eliminates the “I forgot to turn it on” failure mode.

Standing facts

• HRV/ERV installation in BC requires a mechanical permit and a licensed HVAC contractor. Only licensed plumbing, gas, or HVAC contractors can pull a mechanical permit in BC. A homeowner cannot self-permit this work.⁵
• In BC homes built after approximately 2014, a principal ventilation system is required by code — typically an HRV running 24/7, though other compliance paths exist. Newer, tighter homes have fewer natural air leaks and therefore more moisture accumulation without mechanical help.¹
• ERV is generally the better choice for Metro Vancouver over a standard HRV — it transfers both heat and humidity, which helps moderate the extreme swings in outdoor humidity common on the coast.⁶⁷

How it works — the one thing that matters

The moisture truth in coastal BC: rain falls over 160 days per year in Metro Vancouver. Modern construction seals homes tightly for energy efficiency — insulation, vapour barriers, triple-pane windows. A tight home is an efficient home, but it traps moisture generated by breathing, cooking, showers, and drying clothes. Without a deliberate route out, that moisture condenses on the coldest surfaces first: window frames, exterior walls, corners. Condensation feeds mould. This is not a product defect or a strata problem — it is the physics of airtight construction in a wet climate. Ventilation is how moisture leaves the house.

How an HRV (Heat Recovery Ventilator) works: Two fans run simultaneously — one pulls stale, humid indoor air out; the other draws fresh outdoor air in. Both streams pass through a heat-exchange core where they flow in parallel but never mix. The outgoing warm air pre-heats the incoming cold air through the core wall, so you get fresh air without losing the heat you paid for. Heat transfer efficiency is typically 70–85%.²

ERV vs HRV: An ERV (Energy Recovery Ventilator) does the same thing but the core is permeable to water vapour as well as heat. In summer it keeps humid outdoor air from entering the dry-cool interior. In winter it retains some indoor humidity instead of letting it all exhaust. For coastal BC — where outdoor humidity swings from damp winter fog to drier summer heat — the ERV’s moisture management is an advantage. Both types work. ERV is the commonly recommended choice for the Lower Mainland.⁶

Bathroom and kitchen exhaust: These are point-source fans — they pull moisture and pollutants directly at the source and push them outside through a dedicated duct. They are independent of any HRV system and are the cheapest, fastest way to move moisture. The critical rule: every exhaust duct must terminate outdoors with a backdraft damper. A duct that ends in the attic is introducing warm, moist air into a cold space — exactly the conditions for structural rot and mould.¹⁴

So what: the HRV/ERV is the whole-home baseline ventilation. Bathroom and kitchen fans are the point-source surge capacity. Together they form the moisture-removal system. The load-bearing maintenance task — cleaning the HRV filters — is a 20-minute job every three months. Everything else is checking that the ductwork is intact and the fans are running.

CO and radon context: HRV/ERV systems increase air exchange, which helps dilute CO from combustion appliances and radon from soil. They are not a substitute for CO detectors (required by BC Building Code near combustion appliances) or radon testing (new BC homes from March 2024 require sub-slab rough-in for radon mitigation). Ventilation reduces risk; detectors and mitigation address it.⁸

What goes wrong, and the warning signs

Watch for	What it means
Condensation on interior window surfaces regularly	Indoor humidity is too high — HRV may be off, clogged, or undersized; or exhaust fans aren’t running
Mould spots in bathroom corners, closets, or where wall meets ceiling	Moisture is not leaving — a ventilation failure or a point of cold bridging
Musty or stale smell in unit	Air exchange rate is inadequate — check that HRV is on and filters are clear
Ice buildup on HRV exterior vent cap in winter	Normal in cold snaps, but chronic buildup means the cap needs clearing; blocked = no ventilation
HRV running but no airflow at supply vents	Clogged filters, blocked duct, or a failed fan motor — clean filters first
Bathroom fan that hums but moves little air	Worn motor, duct disconnected in wall/attic, or exterior cap blocked
Cooking odours or smoke lingering	Range hood not venting to exterior, or insufficient flow rate
Musty smell from HRV itself	Core needs cleaning (annual pro task) or condensate drain is blocked

What actually fails (the load-bearing failures):

• Clogged filters reduce airflow — this is the dominant, most common failure; it’s also the one owners can fix in 20 minutes.
• Fan motor failure — HRV and bathroom fans have brushless motors that last 10–25 years with maintenance, but filters clogged for years shorten motor life by making them run harder.
• Core freezing in cold weather — rare in Metro Vancouver’s mild winters but possible; defrost cycles should handle it; chronic freezing means the system is not balanced.
• Duct disconnection in walls or attic — especially after renovation work, or in older homes with flexible duct that has separated at joints; result is fan running with no actual air movement.
• Exterior vent cap failure — dampers stick open (cold air backflows in) or closed (no air exchange); replace when the damper no longer moves freely.

When to replace vs repair

What you see	Do this
HRV filters clogged	Clean — the owner task; not a repair
Exterior vent cap blocked or damper stuck	Replace cap — owner-doable; $20–$60 part
HRV running but low airflow after filter cleaning	Call HVAC pro — core cleaning, duct check, or motor diagnosis
Bathroom fan noisy or vibrating	Replace fan unit — owner-doable for a like-for-like swap if you’re comfortable with basic electrical; otherwise an electrician for ~$250–$5509
HRV unit is 20+ years old with declining efficiency	Replace — HRV units last 15–25 years; an aging unit with declining heat-transfer efficiency costs more to run than a new unit
HRV fan motor failed	Repair or replace unit — motor replacement is possible and cheaper than full unit on newer models; on a unit >15 years old, replacement is often better value
Bathroom duct found to be venting into attic	Fix the duct to exterior — not optional; this is a code violation and an active mould risk
Mould found in walls or structure	Call a mould remediation pro — this is beyond ventilation maintenance; structural mould requires professional assessment and remediation before fixing the source

Verdict (replace vs repair framing):

A full HRV/ERV replacement runs $3,500–$7,500 for a retrofit in an existing home¹⁰ — this is irreversible and exceeds the $500threshold,soitearnsfull[[TheDecisionLifecycle]]treatment.Thedecisionis{n}^{\prime }turgentunlesstheunithasfailedorisnearingendoflife.Alike-for-likebathroomfanswapcosts$250–$550⁹ — reversible and low-cost, no full Decision Lifecycle needed; just do it.

→ HRV-vs-ERV-BC-Coastal-Homes (Home Systems)

Typical cost (BC / Metro Vancouver)

Tier	What’s included	Range	Sources
DIY / parts only	HRV/ERV unit alone (no labour, no ductwork, no permit); bathroom fan unit alone	HRV unit: $1,200–$2,500 · Bathroom fan: $30–$400	1011 — indicative (limited sources)
Basic	Like-for-like HRV swap (existing ductwork, same location); or bathroom fan replacement at existing duct — no new duct routing	HRV swap: $2,000–$3,500 · Bathroom fan swap: $250–$550	91011
Standard	New HRV/ERV installation in existing home with existing forced-air ductwork or partial new ductwork; mechanical permit; balancing and commissioning	$3,500–$6,500	101112
Premium	Full retrofit into home with no existing ductwork (standalone ERV with dedicated duct runs throughout home); or large home (>2,500 sq ft) retrofit	$5,500–$9,000+	101112

Metro Vancouver labour rates run 25–40% above the national average.⁹ New construction is substantially cheaper than retrofit — walls are open and ductwork is incorporated into framing; expect $3,000–$5,500 for new builds.¹⁰ Bathroom fan work may require a mechanical or electrical permit depending on scope — confirm with your municipality.

Pricing for HRV installation is difficult to triangulate from public sources because Vancouver HVAC companies rarely publish firm numbers; most provide estimates on-site. The Standard tier above draws from Canadian cost guides (Can Do Duct Cleaning), a Vancouver-based contractor (Penguin HVAC), and a US-based whole-home guide (Rise) with Canadian adjustment — treat as indicative and get 2–3 written quotes. Flag: only one Metro Vancouver company (Penguin HVAC) published a specific figure ($7,200 for new construction including all ductwork); the range above is drawn from multiple sources at the Standard scope.

How to maintain it — the procedures

Procedure: Clean HRV/ERV filters — every 3 months

Why: clogged filters are the primary cause of reduced airflow and poor heat-recovery efficiency. A blocked filter makes the motor work harder and shortens its life. This is the only owner-doable task on the HRV unit itself.³

You’ll need: access to the HRV unit (usually a utility room, basement, or storage closet); running water; somewhere to air-dry filters for 2–4 hours.

1. MUST turn off the HRV at its wall control (or at the breaker) before opening the unit.
2. Open the access panel — it usually unclips or has two thumbscrews.
3. Slide both filters out. Note the airflow-direction arrows on the filter frame.
4. Rinse filters under warm running water — no soap needed for a regular cleaning; mild dish soap is fine for heavily soiled filters. Rinse until water runs clear.
5. Allow filters to air-dry completely (2–4 hours minimum) before reinstalling. MUST NOT reinstall wet filters — this promotes mould in the unit.
6. Reinstall with airflow arrows pointing toward the core, replace the access panel, and restore power.

Done when: both filters are dry, reinstalled correctly, and the HRV restarts and runs without unusual noise.

Stop and call a pro if:

• Filters are damaged (tears, holes) — replace them rather than cleaning
• The unit has no airflow after cleaning — the core, ductwork, or motor needs diagnosis
• You see water pooling inside the unit — the condensate drain may be blocked

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Procedure: Check exterior vent caps — every 6 months

Why: HRV systems have two exterior wall penetrations — one intake, one exhaust — each with a cap and a backdraft damper. A blocked cap stops air exchange entirely. Debris, spider nests, ice, or a failed damper are common.

You’ll need: a step ladder if caps are above reach; a flashlight; 10 minutes.

1. Locate both exterior vent caps on the outside wall (usually side-by-side, typically labelled on or near the HRV unit in the label diagram).
2. Inspect for blockage: leaves, nests, ice buildup.
3. Clear any obstruction — use a gloved hand or soft brush.
4. Open and release the damper flap manually (when the HRV is off) — it should move freely. If it sticks open or closed, replace the cap.
5. Confirm both caps are physically intact (no cracks or gaps that bypass the damper).

Done when: both caps are clear, undamaged, and the damper flaps move freely.

Stop and call a pro if: the cap penetration into the wall looks loose, water is tracking in around the cap, or you cannot reach the cap safely.

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Procedure: Run and verify bathroom exhaust fans — monthly

Why: bathroom fans are the cheapest mould prevention in the home. A fan running but not actually moving air is worse than useless — you think you’re protected but aren’t.

You’ll need: a sheet of toilet paper; 2 minutes.

1. Turn on the fan.
2. Hold a sheet of toilet paper near (not touching) the grill. It should be pulled toward and held against the grill by airflow.
3. If the paper isn’t pulled, the fan is not moving air — check whether the duct is blocked or the motor has failed.
4. Go outside and confirm the exterior vent cap is open and air is flowing out when the fan is on.

Done when: paper is held firmly against the grill and airflow is confirmed at the exterior cap.

Stop and call a pro if:

• Paper is not held and filter/grill cleaning didn’t help — motor or duct fault
• The exterior duct terminates into the attic or a soffit (not outdoors) — this is a code violation requiring duct rerouting; call a contractor

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Procedure: Annual HRV professional service

Why: the core (the heat-exchange element inside the HRV) needs cleaning by a pro approximately once per year in BC. In coastal BC’s damp climate, lint, dust, and moisture residue build up on the core and condensate drain. Core cleaning is not an owner task — water or compressed air applied incorrectly damages the core material.³

You’ll need: a licensed HVAC contractor familiar with your HRV brand; 1–2 hours.

This procedure is “how to set it up,” not how to do it:

1. Book an HVAC tech for a ventilation service annual. Specify your HRV model.
2. The tech will clean the core, clear the condensate drain, check and adjust dampers, measure airflow at supply and exhaust ports, and balance the system if needed.
3. Ask for a written service record stating measured airflow rates before and after.

Done when: you have the service record and the tech confirms balanced airflow within manufacturer spec.

Stop and schedule a second visit if: measured airflow after service is still significantly below spec — duct blockage or motor weakness may be the cause.

Maintenance calendar:

• Monthly: run bathroom fans, check with tissue paper that airflow is present.
• Every 3 months: clean HRV/ERV filters (wash, air-dry, reinstall).
• Every 6 months: inspect and clear exterior HRV vent caps.
• Annually: book HVAC pro for HRV core cleaning, condensate drain, and airflow balancing.
• After any renovation near HVAC ducts: verify duct connections are intact and exhaust terminations still exit to outside (not attic).

Strata reality

Who is responsible for ventilation depends on where the equipment lives.

In a BC strata, the division follows the registered strata plan and bylaws:

• In-unit HRV or bathroom fan — if the unit is inside your strata lot (the common case in townhouse-style stratas and many condos), it is your responsibility to maintain under Standard Bylaw 2.¹³ This includes filter cleaning, annual service, and fan replacement.
• Shared or centrally-ducted ventilation system — some newer strata buildings (especially high-rise condos) have a central air-handling or ventilation system serving multiple units. If the system is in common property, the strata corporation maintains it under SPA s. 72. Confirm with your strata plan which type you have.
• Bathroom fan duct in common property — in some high-rise buildings, individual bathroom fans exhaust through a shared vertical shaft in common property. The fan itself is in your unit (your responsibility); the duct in the shaft is common property (strata’s responsibility). If mould forms in the shaft because a fan is blocked, responsibility gets split — document everything.

The SPA s. 158 connection: if moisture from your unit — caused by inadequate ventilation — damages a neighbouring unit below or beside you (water tracking through the building envelope, condensation-driven rot, mould spreading through shared walls), the strata can claim on its insurance and charge the deductible back to you under SPA s. 158, often regardless of fault if your bylaws use “responsible for” language.¹⁴ Running fans and maintaining the HRV is both a health decision and a liability management decision.

Standard Bylaw 8: alterations to ventilation systems that affect common property (re-routing a bathroom exhaust duct through a shared wall or adding a new HRV penetration) require strata council approval before work begins.

Relevant SPA provisions:

• SPA s. 72 — strata corporation must repair and maintain common property
• Standard Bylaw 2 — owner must repair and maintain strata lot
• Standard Bylaw 8 — owner must obtain strata council approval for alterations to common property
• SPA s. 158 — strata can recover deductible from owner whose lot was the origin of a loss

When you hire someone

Ask:

• Are you a licensed HVAC contractor (Refrigeration Mechanic / Gas Fitter) registered to pull a mechanical permit in BC?
• Will you pull the mechanical permit and coordinate the inspection?
• Are you sizing the HRV/ERV to the home’s floor area and occupancy, or matching the existing unit spec?
• What brand and model are you quoting, and what is its sensible heat recovery efficiency (SRE)?
• Does the quote include balancing and commissioning (airflow measured and adjusted at each vent)?
• Is ductwork included or quoted separately?
• For bathroom fan replacement: is the existing duct run to the exterior verified before the new fan is installed?

Verify the work:

• Permit issued and inspection passed before walls or ceiling access is closed
• Airflow measured at supply and exhaust vents — written record provided
• System is balanced (supply and exhaust flow within manufacturer spec)
• All exterior vent caps are intact, dampers move freely, and terminations are to the exterior (not into any interior space)
• For a new HRV: no audible duct leaks when running at high speed
• For a bathroom fan: exterior termination confirmed with a tissue test after installation

Who to call

These become real when filled in the Tier-B MOCs:

• HVAC contractor (licensed Refrigeration Mechanic or Gas Fitter, BC mechanical permit holder) → vendor-roster (Home Systems). Fill: company name, licence type, phone, notes on HRV/ERV experience and willingness to pull mechanical permits for strata units.
• Insurer / broker → insurance-warranties (Home Systems). Fill: confirm whether your policy covers water damage originating from ventilation failure (backed-up condensate, duct breach into attic causing rot); and whether the strata’s deductible chargeback under SPA s.158 is covered by your personal liability.
• Strata manager → Strata MOC. Fill: confirm whether your unit’s HRV is in your strata lot or common property; get a copy of the strata plan showing ventilation system designation; confirm whether Standard Bylaw 8 approval is needed for any exhaust duct alteration.

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Sources

Idea Compass

North: Where this comes from

• HVAC (Home Systems) — parent system
• Coastal-BC-Tight-Homes-Need-Mechanical-Ventilation-to-Remove-Moisture (Home Systems) — the physics driving the requirement
• BC Building Code Section 9.32 — the governing standard for residential ventilation

East: Tensions / failure

• Bathroom-Fan-Must-Vent-to-Exterior-Not-Attic-BC (Home Systems) — the most common installation defect and code violation
• interior-walls (Home Systems) — mould in walls is where ventilation failure becomes structural damage
• The Strata Insurance Circularity Problem — moisture from inadequate ventilation → neighbour damage → deductible chargeback

South: Where this leads

• HRV-vs-ERV-BC-Coastal-Homes (Home Systems) — the selection decision when replacing or installing new
• HRV-Quarterly-Filter-Cleaning-Is-the-Whole-Owner-Job (Home Systems) — the high-leverage owner task
• vendor-roster (Home Systems) — HVAC contractor named-resource card
• range-hood (Home Systems) — kitchen exhaust is the point-source complement to whole-home HRV

West: What’s similar

• hvac-filters (Home Systems) — same filter-cleaning discipline applied to furnace side
• heating-system (Home Systems) — HRV is often integrated with the forced-air heating system ductwork
• humidifier-dehumidifier (Home Systems) — the other side of moisture management (adding vs removing)
• water-heater (Home Systems) — same strata SPA s.158 chargeback exposure when moisture damage originates in your unit

Footnotes

1. BC Building Code, Section 9.32 — principal ventilation system requirement (continuous operation); exhaust ducts must vent to exterior insulated at RSI 0.75; no termination into attic, soffit, or crawl space — search results from https://free.bcpublications.ca/civix/document/id/public/bcbc2018/bcbc_2018dbp9s932 (PDF rendering blocked; requirement confirmed in search results across multiple BC municipal bulletins including Surrey Builders Forum) ↩ ↩² ↩³

2. Natural Resources Canada, federal government — HRV/ERV operation requirements; continuous operation except when servicing; heat recovery up to 80%; filter cleaning every 1–3 months — https://natural-resources.canada.ca/energy-efficiency/energy-star/products/list-certified-products/heat-energy-recovery-ventilators ↩ ↩²

3. Industrial Monitor Direct, trade reference — complete HRV filter cleaning procedure; every 3–6 months; do not clean core with water unless manufacturer-directed; vacuum interior compartment during 6–12 month service — https://industrialmonitordirect.com/blogs/knowledgebase/hrv-filter-cleaning-complete-homeowner-maintenance-guide ↩ ↩² ↩³

4. HealthLink BC, BC government — exhaust fans in kitchens and bathrooms; vented outdoors; run during and 30 min after showering; clothes dryers vented to exterior — https://www.healthlinkbc.ca/healthlinkbc-files/indoor-air-quality-mould-and-other-biological-contaminants ↩ ↩²

5. City of Vancouver, BC government — mechanical permit required for HRV installation and ventilation system work; only licensed contractors may apply — https://vancouver.ca/home-property-development/mechanical-permit.aspx (page 403’d at time of research — treat as indicative; confirmed by multiple HVAC contractors that a mechanical permit is required in BC) ↩

6. Rep-Air Heating & Cooling, Mission BC HVAC contractor — ERV vs HRV for BC Lower Mainland; ERV recommended for mixed coastal climate; HRV for colder, drier climates — https://www.repairheatingandcooling.com/blog/the-differences-between-hrv-and-erv-systems ↩ ↩²

7. Make It Right / Holmes Media, Canadian home improvement — HRV and ERV differences; ERV recommended for areas with humid summers and dry winters; both must run continuously; up to 80% heat recovery — https://makeitright.ca/holmes-advice/home-safety-maintenance/heat-and-energy-recovery-ventilators-hrv-and-ervs/ ↩

8. BC Building Code and Health Canada — radon rough-in required for new BC construction from March 2024; CO detectors required near combustion appliances; ventilation increases dilution but does not replace mitigation — https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/construction-industry/building-codes-and-standards/bulletins/2024-code/b24-03_radon.pdf ↩

9. Vancouver General Contractors, Metro Vancouver renovation guide — bathroom exhaust fan replacement costs: basic replacement $250–$550 (electrician 1–2 hours); upgrade same duct $350–$750; new duct run $600–$1,500; combo fan/light/heat $500–$1,200; smart fan with humidistat $400–$900; Vancouver labour 25–40% above national average — https://vancouvergeneralcontractors.com/bathroom-exhaust-fan-cost-vancouver/ ↩ ↩² ↩³ ↩⁴

10. Can Do Duct Cleaning, Canadian HVAC reference — HRV unit cost $1,200–$2,500; retrofit total by home size: up to 1,500 sq ft $3,500–$5,000; 1,500–3,000 sq ft $4,500–$6,500; over 3,000 sq ft $5,500–$7,500+; new construction $3,000–$5,500; labour $1,500–$4,000 in retrofits — https://candoductcleaning.com/heat-recovery-ventilator-cost/ ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

11. Build With Rise, whole-home ERV/HRV installation guide — equipment $1,200–$2,500; ductwork $500–$1,500; electrical/controls $300–$600; labour largest single factor; existing-home retrofit $2,500–$6,000+ USD (indicative for Canada with adjustment; no BC-specific data) — https://www.buildwithrise.com/stories/whole-home-erv-hrv-installation-cost-guide ↩ ↩² ↩³ ↩⁴

12. Penguin HVAC, Vancouver HVAC contractor — average HRV installation in Canada $7,200 during framing of new construction; cost fluctuates by system size, complexity, and brand; licensed certified installers in BC — https://www.penguinhvac.ca/hrv-installation ↩ ↩²

13. Province of BC, BC government — division of repair duties in a strata; Standard Bylaw 2 owner responsibility for strata lot repair and maintenance — https://www2.gov.bc.ca/gov/content/housing-tenancy/strata-housing/operating-a-strata/repairs-and-maintenance/division-of-repair-duties ↩

14. BC Strata Property Act, s. 158 — strata may recover insurance deductible from owner whose lot was origin of a loss; deductible chargeback regardless of fault under many BC bylaws — https://www.bclaws.gov.bc.ca/civix/document/id/complete/statreg/98043_09 ↩