Hearing night scratches or finding pellets by the stove? Rodents don’t “appear” — they enter through gaps you can measure and seal. In Metro Vancouver, mice fit through 6 mm (¼") and rats through 12 mm (½") openings around doors, vents, utilities and rooflines. Use this quick guide to locate rodent entry points, hard-seal them, and decide DIY vs. professional exclusion.
Why Rodent Entry Points Matter
- Small gaps, big problems: flexible shoulders let mice/rats compress through 6–12 mm openings.
- Heat & food scent: warm air leaks and kitchen odours act like beacons at night.
- Gnaw to fit: rodents enlarge soft materials (vinyl, foam, wood) to make reliable runways.
- Once inside: wiring, insulation and food contamination drive costs far beyond simple sealing.
Pre-Inspection Checklist (10–20 minutes)
- Walk the exterior with a flashlight: check door bottoms, garage seal, and corners where siding meets slab.
- Look for rub marks/grease on pipes and along foundation ledges; follow to gaps.
- Inspect utility penetrations (gas, cable, AC lines, conduit) and crawlspace hatches.
- From inside, scan under sinks and furnace room for pellets, gnawing, or daylight around pipes.
- Clear 30–60 cm of vegetation and stored items from the foundation to reveal holes.
Same-Day Actions (Safe & Effective)
- Install door sweeps; close garage doors fully and replace brittle bottom seals.
- Pack gaps with steel/copper mesh then cap with exterior-grade sealant or mortar (not foam alone).
- Cover vents with ¼" galvanized hardware cloth (behind existing louvers).
- Place snap traps/monitors along walls where droppings appear; keep food sealed and pet bowls up overnight.
- Avoid interior poison if you haven’t sealed — exclusion first prevents dead-in-wall odours.
Entry Points to Seal First
- Exterior doors & garage bottom — add sweeps/thresholds; no daylight visible.
- Pipe & cable penetrations — gas line sleeves, AC lines, conduit, hose bibs.
- Crawlspace vents & access hatches — screen with ¼" mesh, latch tight.
- Foundation cracks & slab gaps — mortar/epoxy where rodents follow edges.
- Roofline gaps — soffit returns, gable ends, and uncapped chimneys; screen attic/gable vents.
Rodent Entry Cheat-Sheet
| Sign | Likely Areas | Fast Win |
|---|---|---|
| Daylight under door | Front, side, and garage doors | Install brush/rubber sweeps; adjust threshold |
| Rub/grease marks | Along foundation ledges, pipes, sill plate | Track path; mesh + seal the nearest gap |
| Pellets & gnawing | Under sinks, furnace room, pantry | Set snap traps; seal pipe cutouts and kick plates |
| Soil holes at slab | AC line entry, utility corners, stairs | Backfill, compact, mesh the penetration, then caulk |
DIY vs Professional Exclusion
DIY succeeds on light activity with disciplined sealing (mesh + sealant), door hardware fixes, sanitation, and trap placement along walls.
Professional service is best for roofline entries, ongoing nightly droppings, odors in walls, multi-unit buildings, or when you need a full exclusion map and follow-ups.
When to Call Primary Pest Control
- You hear ceiling/wall scratching or find fresh pellets daily.
- There’s chewed wiring/hoses or water damage from gnawing.
- You want hard-seal exclusion (hardware cloth, metal flashing, mortar) plus interior trapping and proofing.
Rodent Exclusion & Entry-Point Hardening • (604) 716-6027
Service Area
Vancouver • Burnaby • Richmond • Surrey • New Westminster • Coquitlam • Port Coquitlam • Port Moody • North Vancouver • West Vancouver • Langley • Delta • Maple Ridge
FAQs
How small a gap can a mouse or rat use?
Mice fit through about 6 mm (¼"); rats need roughly 12 mm (½"). If a pencil fits, a mouse likely can.
What materials actually stop rodents?
¼" galvanized hardware cloth, steel/copper mesh + high-quality sealant, metal flashing, and properly fitted door sweeps. Avoid foam alone — they chew through it.
How long until activity stops after sealing?
With thorough sealing and trapping, most homes quiet within 1–2 weeks. Keep monitors for 30 days and recheck exterior seals seasonally.