Structural — System Brief
The Structural system is the building envelope and load-bearing skeleton: everything that keeps water out, heat in, and the house from moving. It spans eight components from the footing to the ridge. The single most important thing to get right across the whole system is water management — virtually every catastrophic structural failure in a Metro Vancouver home traces back to water that was let in somewhere and given nowhere to go.
The rules that matter most (system-wide tripwires)
Pull these from all eight components. These are the triggers — if any fires, act that week.
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Horizontal foundation crack of any width → engineer assessment, now. Width doesn’t matter. Horizontal = lateral soil pressure = wall beginning to bow inward. Do not inject, do not monitor. Call a P.Eng. → foundation (Home Systems)
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Pre-1985 clay-tile perimeter drain, or pre-2005 corrugated black plastic → plan replacement within 5 years. A camera inspection confirms the era. Delay = emergency pricing. → foundation-drainage-waterproofing (Home Systems)
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Efflorescence (white chalky powder) on basement walls → trace the drainage source before sealing anything. It is water moving through the wall. Sealing over it without fixing the drain just moves the failure point. → foundation-drainage-waterproofing (Home Systems)
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Bathroom or kitchen exhaust duct terminating inside the attic → fix immediately. A single fan venting into the attic can push sheathing moisture above the mould threshold (20% MC) within one winter. Rerouting is a licensed-contractor job. → attic (Home Systems)
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Frost, condensation, or dark staining on attic sheathing underside → call a building-science pro within a week. That is mould-threshold moisture; it is not monitor-and-wait. → attic (Home Systems)
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Musty smell, soft/spongy floors, or standing water in the crawlspace → pro assessment immediately. Floor joists may already be structurally compromised. → crawlspace (Home Systems)
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No ground vapour barrier in the crawlspace → install 6-mil poly before anything else. It is the single highest-leverage crawlspace fix available to the owner. → crawlspace (Home Systems)
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Fogging or condensation between the panes (cannot be wiped from inside) → replace the IGU, not the whole window. Frame is almost always still sound. Full-window replacement is expensive and usually wrong. → windows (Home Systems)
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Cracked, mouldy, or pulled-away caulk at tub/shower/toilet base → replace it now. Wet-area caulk failure is silent. By the time the floor feels soft or the tile pops, the rot is already there. → caulking-seals (Home Systems)
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Multiple doors sticking together, alongside wall cracks or sloping floors → stop and call a structural engineer before adjusting anything. Multi-door sticking is a foundation signal, not a hinge problem. → doors (Home Systems), foundation (Home Systems)
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Any structural foundation repair (crack injection, carbon-fibre straps, underpinning) → engineer sign-off and building permit before the contractor starts work. A contractor’s recommendation alone is not sufficient. The engineer designs the fix; the contractor executes to the stamped drawings. → foundation (Home Systems)
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Insulation work planned → air-seal the assembly first. Insulation over air leaks makes moisture damage worse. Adding R-value without sealing is the single most common insulation mistake in BC. → insulation (Home Systems)
Component-by-component
| Component | The one thing to watch | Owner vs pro |
|---|---|---|
| foundation (Home Systems) | Crack direction — horizontal is always serious regardless of width; measure and date everything else annually | Owner monitors; engineer assesses; contractor executes to engineer’s scope |
| foundation-drainage-waterproofing (Home Systems) | Perimeter drain pipe era (pre-1985 clay or pre-2005 corrugated plastic = end of life); sump pump test every September | Owner: downspout extensions, regrading, sump bucket test; pro: camera inspection, hydro-flush, any excavation |
| windows (Home Systems) | Fogging between panes = IGU only (not full window); interior condensation = ventilation problem; water at sill = get leak assessment before caulking | Owner: weep holes, perimeter caulk, weatherstripping; pro: IGU swap, full window, flashing |
| doors (Home Systems) | Weather-seal integrity — daylight, cold air, or water around any exterior door means reseal this season; single sticking = hinge wear; multiple sticking = foundation signal | Owner: weatherstripping, sweep, hinges, patio track; pro: rot repair, full replacement |
| caulking-seals (Home Systems) | Product-to-location match — silicone in wet areas, paintable hybrid/polyurethane on exterior, acrylic latex on dry trim; never caulk over old caulk | Largely owner-doable; pro for large exterior envelope scope or substrate damage underneath |
| attic (Home Systems) | Exhaust fans must exit outside; ceiling-plane air sealing and R-40+ insulation work together; inspect annually before the wet season | Owner: hatch insulation, humidity monitoring, annual visual; pro: air sealing, blown-in top-up, mould remediation |
| crawlspace (Home Systems) | Continuous ground vapour barrier is the first fix; monitor RH below 55–60% if sealed; sealed crawlspace performs better than vented in coastal BC | Owner: vapour barrier install (DIY-doable), annual visual, humidity sensor; pro: encapsulation, joist repair, mould |
| insulation (Home Systems) | Seal air leaks before adding R-value — insulation does not stop air movement; attic is the biggest bang-for-buck zone in Metro Vancouver; rim joist is the owner-doable quick win | Owner: rim joist spray foam, attic hatch; HPCN contractor for rebate-eligible blown-in; pro only for dense-pack walls and asbestos removal |
Recurring upkeep at a glance
All items below belong in the Maintenance Calendar (Home Systems).
Annual (fall, before the October–March wet season):
- Foundation perimeter walk — grade, efflorescence, pooling, downspout discharge check → foundation-drainage-waterproofing (Home Systems)
- Sump pump bucket test → foundation-drainage-waterproofing (Home Systems)
- Window weep holes cleared; perimeter caulk inspected → windows (Home Systems)
- Door weatherstripping and sweep inspected; patio track cleaned → doors (Home Systems)
- Exterior caulk joints walked (all window/door perimeters, penetrations) → caulking-seals (Home Systems)
- Attic inspection (insulation depth, moisture, vents, pest signs) → attic (Home Systems)
- Crawlspace inspection (visual for water, odour, mould, pest activity) → crawlspace (Home Systems)
Annual (spring, after the wet season):
- Foundation visual inspection — measure and photograph all known cracks, check for new ones → foundation (Home Systems)
- Wet-area caulk checked (tub, shower, toilet base) → caulking-seals (Home Systems)
Every 3–7 years (or after any sign of slow drainage):
- CCTV camera inspection of perimeter drain → foundation-drainage-waterproofing (Home Systems)
Every 3–5 years:
- Wet-area caulk proactive replacement → caulking-seals (Home Systems)
Every 5–10 years:
- Exterior caulk full reseal → caulking-seals (Home Systems)
- Sump pump lifecycle replacement (7–10 year lifespan) → foundation-drainage-waterproofing (Home Systems)
One-time setup (at purchase or move-in):
- Confirm foundation type, photograph baseline, vet a structural engineer → foundation (Home Systems)
- Pull drainage section from home inspection report or book camera inspection → foundation-drainage-waterproofing (Home Systems)
- Confirm attic R-value and all exhaust fans exit outside → attic (Home Systems)
- Confirm vapour barrier in crawlspace; test for radon → crawlspace (Home Systems)
- Confirm current insulation R-value; pre-register for BC Hydro / FortisBC rebates before signing any insulation contract → insulation (Home Systems)
- Strata only: read strata plan before spending on windows, doors, or any exterior work → windows (Home Systems), doors (Home Systems)
Biggest-cost / irreversible decisions
These are the decisions that route to finance-replacement-reserves (Home Systems) and require the full The Decision Lifecycle before committing.
| Decision | Irreversible? | Typical cost range | Component |
|---|---|---|---|
| Full exterior perimeter drain replacement | Yes — excavation cannot be undone in 30 days | 35K+ exterior; 18K interior retrofit | foundation-drainage-waterproofing (Home Systems) |
| Structural foundation repair (straps, anchors, underpinning) | Yes — cannot be un-installed | 200K+ depending on method | foundation (Home Systems) |
| Attic mould remediation + full insulation replacement | Yes — remediated sheathing cannot be un-remediated | 15K+ | attic (Home Systems) |
| Crawlspace encapsulation | Borderline reversible; >$500 | 16K Metro Vancouver | crawlspace (Home Systems) |
| Full-suite window replacement | Yes per opening | 17K for a typical home | windows (Home Systems) |
| Exterior door replacement | Yes | 6K depending on type | doors (Home Systems) |
| Full wall insulation retrofit or asbestos insulation removal | Yes — wall opening or abatement | 10K+ | insulation (Home Systems) |
Decisions that do NOT need the full process — just do them:
- Sump pump replacement (1,200) — routine, reversible
- IGU-only window replacement (600) — reversible, low-cost
- Weatherstripping, door sweep, hinge screws — all DIY-reversible
- Caulk replacement anywhere — always reversible
- Attic insulation top-up to R-50 (no removal, no asbestos) — above $500 but straightforward; HPCN contractor for rebate
- Crawlspace vapour barrier (DIY 400; pro 4,000) — reversible
Strata vs detached
| Component | Strata owner scope | Strata corporation scope | Detached owner scope |
|---|---|---|---|
| Foundation (walls, footings, slab) | Report structural concerns in writing; document | Common property — SPA s.72 maintenance obligation | Entirely yours — assessment, repair, permit, cost |
| Foundation drainage / waterproofing | Report symptoms in writing; maintain your own window well if in your lot boundary; check bylaws for in-unit sump | Perimeter drain is common property (SPA + Chapel CRT 2017) | Entirely yours — full scope including camera, contractor, permit |
| Windows (exterior) | Check strata plan before spending; strata council approval required for any alteration | Exterior windows are generally common property in BC strata | Entirely yours |
| Windows (interior seals/hardware) | Typically owner scope — weatherstripping, weep holes, interior caulk | — | Owner |
| Exterior doors (entry door) | Standard Bylaw 8 — strata council approval before any alteration; check whether bylaw shifts maintenance to owner | Entry door fronting common property is generally strata’s under Standard Bylaw 8 | Entirely yours |
| Caulking (exterior envelope) | Generally strata responsibility; interior wet-area caulk is owner scope | Exterior envelope caulking | Both — confirm with bylaws |
| Attic | N/A — not accessible in most strata | Common property in most strata buildings | Entirely yours — insulation, venting, moisture, pest |
| Crawlspace | N/A — not typical in strata | Common property where it exists | Entirely yours |
| Insulation (building envelope) | Confirm scope before spending; rim joist/partition walls may be owner scope | Exterior wall, roof, and building underside insulation is generally common property | Entirely yours |
Key strata insurance exposure: water damage from a blocked common-property drain or failed window that saturates a shared wall can trigger a strata deductible chargeback (250K+) to the owner under SPA s.158. Report symptoms in writing as soon as you see them — that is the procedural defence. → insurance-warranties (Home Systems)
What this brief is NOT
This brief is a synthesis layer — one screen of ranked signal from eight component notes. It is not a substitute for the component notes themselves. Each component note contains:
- The full mechanism explanation (What / Why / So What)
- Complete warning-sign discrimination tables
- Detailed DIY maintenance SOPs (step-by-step, with “stop and call a pro if” gates)
- Triangulated cost tables with sources
- Strata vs detached reality sections
- Named-resource card placeholders for vendors, insurer, and strata contacts
- Atomic Q-I-ST children linked via Idea Compass
Start here to orient. Open the component note when you need to act.
→ Structural (Home Systems) — the system MOC with the full Component Index → Home Systems KB MOC — the top-level KB hub