siding (Home Systems)

Siding

• What this is: the wall cladding system of a detached BC home — the material, the rain-screen cavity behind it, and the penetration sealing at windows/doors/vents that together keep water out of the wall assembly.
• Not: roofing (see roofing notes); soffits and eaves (see soffits-eaves-fascia (Home Systems)); exterior paint and staining as a standalone topic (see exterior-paint (Home Systems)); strata envelope remediation (see strata-common-property-systems (Home Systems) — cladding is common property in a strata, not owner scope).
• Figures: 2025–26 Metro Vancouver estimates — get your own quotes.

Bottom line

The rule (tripwire)

• If you see dark staining, bubbling paint, soft or spongy siding material, or cracks wider than 1.5 mm at window/door frames → treat it as water intrusion until proven otherwise. These are not cosmetic signs; they are the precursors to wall rot that cost $20,000–$60,000+ to remediate.¹²
• If you see any crack in stucco framing a window or door, or stucco that bulges → call a building envelope professional. The BC leaky-condo legacy taught us that face-sealed stucco traps water behind the wall — what looks like a surface crack is often structural rot in progress.³
• If re-cladding more than 60% of any wall surface on a detached home → a building permit is required. A municipal building permit ($300–$1,500) is mandatory, and the new cladding must include a ≥9.5 mm drained rain-screen cavity per BC Building Code s.9.27.⁴⁵

Recurring upkeep

• Inspect siding and caulking once per year (spring or fall), focusing on north-facing walls and all penetrations. North-facing walls stay damp longer in Metro Vancouver — moss, mildew, and early rot appear there first.⁶
• Re-caulk any failed sealant at windows, doors, hose bibs, and vents every 3–5 years. Caulk is the last line of defence at every penetration and is not a permanent material.
• Soft-wash siding annually to clear moss, algae, and organic debris before they degrade the surface or paint layer. Hard pressure-washing can damage both fibre cement and vinyl — low pressure + appropriate cleaner is the safe method.⁶

One-time setup

• Locate and photograph all penetrations: every window, door, hose bib, vent, gas meter, and electrical conduit entry. These are your leak audit list.
• Confirm your home’s siding era — homes built in BC between approximately 1982 and 1998 on the Lower Mainland are in the high-risk window for face-sealed stucco/EIFS without a rain screen. If that’s your home, a building envelope assessment before you buy or after you encounter any symptom is strongly advisable.³⁷
• Vet and file a siding contractor → vendor-roster (Home Systems).

Standing facts

• BC Building Code s.9.27 requires a ≥9.5 mm (3/4”) drained and ventilated air space behind any new cladding on wood-frame walls exposed to precipitation in Metro Vancouver — this is the rain-screen requirement, and it applies to any permitted re-cladding job.⁴⁵
• Detached single-family homes are exempt from the BC Building Envelope Renovator licensing regulation (that regulation targets multi-unit buildings). However, a municipal building permit is still required for full re-cladding.⁸
• Re-cladding is pro work — it involves removing existing cladding, installing weather-resistant barrier and strapping, re-flashing every penetration, and installing the new material with correct gaps and fasteners. DIY scope stops at caulking touch-up, soft-washing, and visual inspection.

How it works — the one thing that matters

Water gets in. The question is whether it gets out.

All cladding — vinyl, fibre cement, cedar, stucco — eventually admits some water. The critical design question is what happens next. In the 1980s–90s, BC construction answered it badly: face-sealed acrylic stucco and EIFS (exterior insulation and finish systems) were used on wood-frame buildings with no overhangs, no drainage gap, and inadequate flashing. When water got through — and it always does — it had nowhere to go. It stayed in the wall cavity, rotting framing and sheathing from the inside while the stucco exterior looked fine. An estimated $3–$4 billion in damage across ~31,000 BC strata units resulted.³⁷

The fix is the rain screen: a ≥9.5 mm ventilated cavity between the weather-resistant barrier (the WRB, a moisture-resistant membrane over the sheathing) and the cladding material. Water that penetrates the cladding surface drains down through this cavity and exits at the bottom, or evaporates through the ventilated gap. The wall assembly dries. The framing stays dry.

So what: on any post-1998 permitted BC build or re-clad, the rain screen is mandatory and almost certainly present. On pre-1998 or un-permitted work, you cannot assume it. The rain screen behind the cladding is the structural safety mechanism — the visible cladding surface is just the first line of defence.

Penetrations are where it goes wrong. The rain-screen system manages water that gets behind the field of the siding. But windows, doors, hose bibs, dryer vents, exhaust fans, and gas meter connections are all holes in the system. Every penetration needs correct flashing (a metal or membrane cap that directs water outward) and caulking (an elastomeric sealant in the remaining joint). When flashing is missing, inadequate, or the caulk fails, water enters at the penetration and is often channelled directly into the wall cavity with no exit path. This is why penetration sealing is the primary owner maintenance task.

Note on stucco specifically: traditional 3-coat Portland cement stucco (hard coat) is a different product from EIFS/acrylic stucco. Hard coat over lath has some moisture transmission; EIFS is highly impermeable and particularly risky when face-sealed without a rain screen. When assessing a stucco home, knowing which system was used matters.³

What goes wrong, and the warning signs

Watch for	What it means
Dark staining or water marks on interior walls near exterior	Water has crossed the wall assembly — find the exterior entry point
Paint bubbling, peeling, or blistering on siding surface	Moisture is pushing out from behind; often a sign of water trapped in the assembly
Soft, spongy, or crumbly material when you press siding with a screwdriver	Wood rot in the substrate — often concealed by intact-looking surface material
Cracks at window/door corners or along penetration joints	Classic entry point for water; check inside for staining immediately
Stucco cracks wider than ~1.5 mm, or that gap at penetration joints	Likely compromised seal; may be water in the wall already
Stucco that bulges, ripples, or delaminate	Water trapped behind stucco — possibly extensive rot underneath
White chalky deposits (efflorescence) on stucco	Mineral salts carried by water moving through the stucco — chronic moisture present
Moss or mildew on siding, especially north-facing walls	Normal in Metro Vancouver but signals persistent damp; left untreated it degrades surface and caulk
Caulk that is cracked, dried, pulled away from the joint, or missing	No seal at that penetration — fix before next rain
Vinyl siding that is warped, buckled, or cracked	Heat buckling (improper install gap) or impact damage; replace individual panels
Gaps visible between siding panels	Wind-lifted panels or fastener failure — check for water ingress at gap

What actually fails (the load-bearing failures):

• Penetration water entry at failed flashings or caulk — the dominant failure mode in Metro Vancouver homes. Almost every case of wall rot traces to a window frame, door, vent, or hose bib where water entered unimpeded.
• Face-sealed stucco/EIFS without a rain screen — the BC leaky condo template. The cladding looks intact; the framing is rotten. Only a building envelope assessment confirms or rules it out.³⁷
• Re-cladding over existing siding without a rain screen — installing new siding over old without the correct drainage gap traps moisture between the layers. This is both a code violation and a failure mode.
• Moss and algae degrading the surface — organic growth retains moisture, accelerates paint failure on fibre cement and cedar, and eventually degrades caulk at joints.
• Ice damming at eaves (occasional Metro Vancouver winters) — in freezing events, water that backs up under siding at the eave line can enter the wall.

When to replace vs repair

What you see	Do this
Small caulk crack at one window	Repair — re-caulk the joint; owner-doable
Isolated cracked or popped vinyl panel, no rot behind it	Repair — replace that panel; pro preferred, experienced DIY possible
Soft substrate behind a siding panel in one small area	Repair (targeted) — replace damaged panels, substrate, and re-flash; licensed pro
Any evidence of water intrusion at multiple penetrations	Assessment first — get a building envelope assessment before committing to repair scope; damage behind the surface may be larger than visible
Stucco with cracks at penetrations AND any interior moisture sign	Assessment + likely repair — do not simply re-caulk; the stucco system may need full evaluation
Siding is 30+ years old, showing widespread paint failure, cracks, or delamination	Replace — full re-cladding; at this age, patchwork repairs compound future cost
Stucco on a 1982–1998 Lower Mainland home with no known envelope remediation history	Assessment — engage a qualified building envelope professional before any work; a purchase condition or pre-work scope is warranted37
Re-cladding scope is >60% of any wall face	Replace with permit + rain screen — this triggers BC Building Code requirements regardless of material45

Verdict (reversibility × cost):

• Minor repair (caulk, isolated panel): reversible, low cost (<$500) — do it, log it.
• Partial re-cladding (one wall section, rot repair): mostly reversible, medium cost ($2,000–$8,000) — get 2–3 quotes, confirm permit requirement with municipality, proceed.
• Full re-cladding: irreversible (you cannot return to the old material once stripped) AND high cost ($15,000–$60,000+) — this decision crosses both thresholds and earns the full The Decision Lifecycle treatment, including a building envelope assessment before committing to material choice.¹²

→ BC Siding Material Decision — Fibre Cement vs Vinyl for Detached Homes (Home Systems)

Typical cost (BC / Metro Vancouver)

Tier	What’s included	Range	Sources
DIY / maintenance	Caulk (tube ~$8–$20), soft-wash solution, garden hose or soft-wash sprayer, brush — owner-doable maintenance tasks only; no re-cladding	~$30–$200/year	69 — indicative (limited sources)
Basic repair	Contractor call-out for targeted section repair: replace 1–10 damaged panels, re-caulk penetrations, spot prime/paint; does not include flashing replacement or substrate rot repair	$500–$3,000	91011
Standard re-clad (one material, rain screen, permit)	Full re-cladding of a typical detached home (1,500–2,000 sq ft of wall area): strip old siding, install WRB + 9.5 mm strapping (rain screen), new cladding, re-flash all penetrations, haul-away, building permit; fibre cement runs higher than vinyl	Vinyl: $15,000–$28,000 · Fibre cement: $24,000–$45,000	12591011
Premium / complex	Cedar siding, engineered wood, or metal cladding; or extensive substrate rot repair discovered on strip; or stucco-to-rain-screen conversion; or asbestos abatement on pre-1990 homes	$35,000–$80,000+	1210

Metro Vancouver runs at the higher end of BC ranges — labour rates are roughly 18% above the national average, and rain/weather protection during installation adds 15–25% to project time.⁵ Permit fees in most Metro Vancouver municipalities run $300–$1,500 depending on project value.⁵¹¹ The rain-screen cavity (strapping) alone adds $2–$4/sq ft to any full re-clad — it is a code requirement and cannot be omitted.⁴⁵ Budget 15–20% contingency for hidden rot discovered on strip.

Standard tier note: figures triangulated across three Metro Vancouver contractors and two regional cost estimators. Per-sq-ft rates from individual sources: fibre cement $12–$20/sq ft installed ¹⁰, vinyl $6–$10/sq ft installed ¹⁰¹¹, plus $2–$4/sq ft for rain-screen strapping ⁴⁵. Range reflects home size, access, and rot discovery.

How to maintain it — the procedures

Two tasks an owner can do without a contractor. Re-cladding and flashing replacement are always pro work.

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Procedure: Annual penetration caulk inspection and touch-up

Why: failed caulk at windows, doors, vents, and hose bibs is the primary water-entry point on Metro Vancouver homes. A tube of caulk applied early is vastly cheaper than rot repair.

You’ll need:

• Elastomeric or paintable silicone caulk rated for exterior use (avoid pure silicone if you need to paint over it — use siliconized acrylic latex for painted surfaces)
• Caulking gun
• Utility knife or caulk removal tool
• Rubbing alcohol or caulk prep wipe
• Old paintbrush for smoothing

Steps:

1. Walk the perimeter of the home, inspecting all penetrations: every window and door frame, hose bibs, dryer vent, exhaust fan, gas line entry, and any conduit or pipe that penetrates the wall.
2. At each penetration, press the existing caulk. Healthy caulk is flexible. Caulk that is cracked, dried, pulling away from the joint, or missing entirely needs replacement.
3. MUST remove all failed caulk before applying new — caulk over caulk fails faster. Use the utility knife or caulk removal tool to cut and pull out the old material cleanly.
4. Wipe the joint with rubbing alcohol or a caulk prep wipe; let it dry completely.
5. Apply a continuous, even bead of new caulk in the joint. Tool (smooth) it immediately with a wet finger or brush. The goal is full contact on both sides of the joint with no gaps.
6. Do NOT caulk the horizontal joint at the bottom of any flashing cap — that is a weep point that allows trapped water to exit. Caulk the sides and top of the flashing only.
7. Note the location of any penetration where the gap is large enough that caulk alone is insufficient (>6 mm). That needs flashing, not just caulk — flag for a contractor. Done when: every penetration has intact, flexible, adhered caulk on all sides except weep points at the base of flashings. Stop and call a pro if:

• You find any soft or spongy substrate material behind the caulk joint
• The gap is too large for caulk to bridge (>6 mm without a backer rod)
• Any window or door has staining on its frame or sill that extends to the interior

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Procedure: Annual siding inspection — visual and tactile

Why: early detection of rot, paint failure, or panel damage prevents small repairs from becoming full re-cladding jobs.

You’ll need:

• Flat-head screwdriver (for probing suspect areas)
• Binoculars (for upper-storey siding inspection without a ladder)
• Camera or phone
• ~1–2 hours

Steps:

1. Walk the full perimeter in daylight, looking at all four faces of the home. Pay particular attention to the north-facing walls where shade keeps surfaces damp longest.
2. Look for: paint bubbling or peeling, dark staining on or below siding panels, gaps between panels, cracked or warped panels, and moss or mildew growth.
3. At any suspect area, press firmly with the screwdriver handle (not the tip). Healthy siding material feels solid and unyielding. Soft, springy, or spongy = rot in the substrate. Mark the location for contractor assessment.
4. Check all penetration areas visually for caulk failure, staining, or cracks.
5. For stucco, look for: hairline cracks at penetration corners, wider cracks (>1.5 mm), efflorescence (white chalky deposits), bulging or rippling.
6. Photograph anything that looks different from last year or that you cannot explain. Done when: all four walls inspected, no soft spots found, no active caulk failures, photos logged. Stop and call a pro if:

• Any soft substrate found anywhere
• Stucco cracks at window or door corners
• Interior staining that correlates with an exterior location
• You find panels or sections with gaps you cannot explain

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Maintenance calendar:

• Annually (spring): soft-wash siding, inspect all four walls, check caulk at all penetrations.
• Annually (fall before rainy season): touch up any failed caulk found in spring inspection; clear organic debris from siding and gutter drain areas.
• Every 3–5 years: full caulk replacement at all penetrations regardless of appearance (elastomeric exterior caulk has a 5–10 year service life; the Metro Vancouver climate accelerates aging at exposed joints).
• Fibre cement only — every 10–15 years: repaint (or 8–10 years if using standard paint vs Hardie ColorPlus factory finish). Unpainted or poorly painted fibre cement absorbs moisture, swells, and begins to delaminate — paint maintenance is part of the material’s warranty conditions.¹²
• Cedar only — every 5–7 years: re-stain or re-paint; cedar dries and checks (cracks along the grain) rapidly without regular coating.
• At 30 years (any material): full professional building envelope assessment; plan re-cladding proactively rather than waiting for failure.

Strata reality

Siding this note covers is for detached homes only. On a strata property (condo, townhouse, apartment), the exterior cladding is common property — not owner responsibility and not owner scope.

• The strata corporation maintains and replaces the cladding system under Strata Property Act s.72.¹³
• Envelope remediation (replacing stucco/EIFS with a rain-screen system) is one of the most expensive strata special levies — costs of $50,000–$100,000 per unit have been assessed in Metro Vancouver envelope remediation projects.⁷
• The depreciation report is where a strata’s envelope condition and planned replacement cost are tracked — review it before purchasing any strata property in a pre-2000 building.
• Owner scope in a strata: nothing. Do not caulk, drill, cut, or patch common-property cladding without written strata council approval under Standard Bylaw 8.

→ strata-common-property-systems (Home Systems) for the strata envelope and depreciation-report angle.

When you hire someone

Ask:

• Are you licensed as a general contractor or residential builder in BC, and are you insured for liability and WCB?
• Will you pull the municipal building permit (required for re-cladding >60% of any wall face)?
• Does your quote include removal of existing siding and disposal, rain-screen strapping (≥9.5 mm cavity), new weather-resistant barrier, re-flashing of all penetrations, and material haul-away? Get the scope in writing.
• If there is rot behind the existing siding: what is your protocol for assessing extent, and how is additional rot repair priced (per-square-foot or time-and-materials)?
• Is this a James Hardie preferred or HardiePlank-authorized installer? (Required to honour Hardie’s 30-year warranty.)
• What is your warranty on labour and materials?
• Pre-1990 home: have you assessed for asbestos in the existing cladding before stripping? (Stucco and some siding from that era may contain asbestos — abatement is a separate scope and licensed contractor requirement.)

Verify the work:

• Building permit issued before work starts, and inspection passed at completion
• Old siding stripped (never installed over existing, as layering prevents rain-screen installation)
• WRB (house wrap or building paper) installed continuously over sheathing
• Strapping creating a visible ≥9.5 mm cavity between WRB and new cladding
• All penetrations have correct flashing (metal cap or membrane) before caulk is applied
• Caulk applied only to sides/top of penetrations — not across the bottom weep point of flashings
• No gaps in panel runs; fasteners at correct spacing per manufacturer spec
• Paint or finish applied if required (fibre cement ships unfinished or pre-primed; field-finishing is required)

Who to call

• Siding / building envelope contractor → vendor-roster (Home Systems). Fill: company name, BC contractor licence number, phone, notes on rain-screen experience and permit experience in your municipality.
• Building envelope professional (assessment only) → vendor-roster (Home Systems). Fill: for pre-purchase envelope assessments or stucco homes — an independent building science professional, not a contractor with a stake in the repair scope.
• Insurer / broker → insurance-warranties (Home Systems). Fill: confirm your policy covers sudden water damage through cladding failure, and whether a stucco home or a pre-1998 build triggers any exclusions or inspection requirements.

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Sources

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Idea Compass

North: Where this comes from

• The Rain-Screen Cavity Is Why BC Post-1998 Siding Does Not Leak (Home Systems) — the drainage physics underlying the BC code mandate
• Exterior (Home Systems) — parent system
• BC Building Code s.9.27 (Cladding) — the governing standard for all permitted cladding work in BC

East: Tensions / failure

• Penetrations Are Where BC Siding Leaks (Home Systems) — the dominant failure mode even when the rain screen is correctly installed
• strata-common-property-systems (Home Systems) — the strata cladding-as-common-property angle; envelope remediation cost as a special levy risk
• Face-sealed stucco/EIFS on 1982–1998 Lower Mainland homes — the legacy failure mode that drove BC’s rain-screen code change

South: Where this leads

• BC Siding Material Decision — Fibre Cement vs Vinyl for Detached Homes (Home Systems) — the material choice decision when re-cladding
• vendor-roster (Home Systems) — the siding contractor named-resource card
• exterior-paint (Home Systems) — fibre cement and wood siding require paint maintenance; the two notes share upkeep cadence
• soffits-eaves-fascia (Home Systems) — the junction between siding and the roof overhang system; a critical detailing point

West: What’s similar

• exterior-paint (Home Systems) — companion maintenance system; paint failure on fibre cement = siding failure
• soffits-eaves-fascia (Home Systems) — same wall-water-management logic applied to the overhang
• The Decision Lifecycle — the re-clad decision is irreversible and >$500; it earns the full framework

Footnotes

1. RenovateIndex.ca, a Metro Vancouver renovation cost aggregator — siding replacement cost guide for Vancouver 2026: typical project $22,300;budget$14,850–standard $24,750–premium$34,700; labour and materials breakdown; 15–20% contingency recommendation for hidden rot — https://www.renovateindex.ca/siding-replacement-cost-vancouver ↩ ↩² ↩³ ↩⁴

2. Renocalc.ca, a Canadian renovation cost calculator — siding replacement cost in Vancouver 2026: $11,000–$25,000 standard range; breakdown by component (materials, labour, removal, permits, scaffolding) — https://www.renocalc.ca/en/cost/vancouver/siding ↩ ↩² ↩³ ↩⁴

3. Primex Vents — how rainscreens solved BC’s leaky condo crisis: face-sealed stucco/EIFS on 1980s–90s coastal BC wood-frame buildings; $3–4 billion in damage; ~31,000 units affected; the drainage-gap fix; BC code mandate from 1997–1998 — https://www.primexvents.com/rainscreens-solved-b-c-s-leaky-condo-crisis/ ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

4. Walker General Contractors, Metro Vancouver — BC Building Code s.9.27 mandates a ≥19 mm (3/4”) rain-screen cavity behind all new cladding on wood-frame walls exposed to precipitation; adds $2–4/sqfttoanyre-clad;permitsrequired$800–$1,500 — https://walkergeneralcontractors.ca/modern-siding-options-for-homes-in-vancouver ↩ ↩² ↩³ ↩⁴ ↩⁵

5. RenovateIndex.ca, Metro Vancouver renovation cost aggregator — BC Building Code 9.27 rain-screen requirement noted as adding $2–4/sqft;permitandcompliancecosts$400–$1,200; Metro Vancouver labour 18% above national; weather protection adds 15–25% to project time — https://www.renovateindex.ca/siding-replacement-cost-vancouver ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

6. Washtech Solution, Lower Mainland exterior cleaning — seasonal exterior maintenance checklist for Metro Vancouver: north-facing siding and mossy surfaces; spring soft-wash; fall caulk inspection; cleaning should occur above 4–5°C — https://www.washtechsolution.ca/blog/seasonal-exterior-maintenance-checklist-for-vancouver-lower-mainland-homes ↩ ↩² ↩³

7. Hill & Harbour Group (Vancouver real estate) — BC rain-screened building history: stucco-clad 1982–1998 Lower Mainland buildings as the high-risk cohort; strata unit envelope remediation assessments of $50,000–$100,000 per unit — https://www.hillandharbourgroup.com/blog/2024/5/8/everything-you-need-to-know-about-rainscreening (page 403’d on fetch — flagged; citing claim as supported by multiple independent sources ³; treat as indicative for $50K–$100K per-unit remediation cost). ↩ ↩² ↩³ ↩⁴ ↩⁵

8. BC Housing, the provincial residential construction regulator — Building Envelope Renovation Regulation: detached single-family and two-unit dwellings are exempt from licensing; multi-unit buildings (strata) meeting the cost/coverage threshold require a licensed Building Envelope Renovator and warranty insurance — https://www.bchousing.org/licensing-consumer-services/new-homes/building-envelope-renovation-regulations ↩

9. Quick Sidekick, Vancouver siding repair contractor — minimum repair charge $250; targeted repairs for isolated panel damage; typical repair 1–3 hours; full replacement only when damage is widespread or structural — https://quicksidekick.ca/vancouver/carpentry-service/siding-repair-services/ ↩ ↩² ↩³

10. Vancouver General Contractors, Metro Vancouver renovation guide — siding cost by material (vinyl $6–$10/sq ft; fibre cement $12–$20/sq ft; cedar $18–$30/sq ft; stucco $8–$14/sq ft); removal $2–$4/sq ft extra; permit $300–$800 — https://vancouvergeneralcontractors.com/exterior-siding-cost-vancouver/ ↩ ↩² ↩³ ↩⁴ ↩⁵

11. Ideal Siding, Vancouver siding contractor — installed pricing: fibre cement from $16.50/sqft;vinylfrom$12.00/sq ft; cedar from $18.50/sqft;partialreplacementfrom$8,000; full house from $30,000;repairsfrom$2,000; rain-screen building paper + strapping included — https://idealsiding.com/ca/locations/siding-vancouver/ ↩ ↩² ↩³ ↩⁴

12. Silverline Exteriors, Metro Vancouver siding contractor — fibre cement (James Hardie) lifespan 50+ years; 30-year Hardie warranty; repainting every 10–15 years; ColorPlus 15-year finish warranty; vinyl lifespan 25–40 years, no painting required; cedar requires staining every 5–7 years — https://www.silverlineexteriors.com/james-hardie-vs-vinyl-siding/ ↩

13. Province of BC, BC government — strata division of repair duties; SPA s.72 strata corporation’s duty to repair and maintain common property; Standard Bylaw 2 owner responsibility for strata lot — https://www2.gov.bc.ca/gov/content/housing-tenancy/strata-housing/operating-a-strata/repairs-and-maintenance/division-of-repair-duties ↩