Rat in your attic? A North Shore homeowner's emergency playbook

Confirm it's roof rats, not squirrels

Squirrels are the other common BC attic occupant. Squirrels are diurnal — most active during daylight, especially morning and early evening. Roof rats are nocturnal — active 10pm to 4am. Squirrel droppings are 8-10 mm and cylindrical, typically clustered near visible entry; roof rat droppings are 12-15 mm, curved, scattered along beams and on insulation. Squirrels gnaw visible roof penetrations; roof rats slip in through pre-existing soffit and roof return gaps without much damage.

What to check tonight

Sit quietly under the attic at 10pm-1am. Note the location and direction of running sounds. Roof rats run along ceiling joists and beams in patterned runways.
Open the attic hatch with a flashlight (do not enter without proper PPE — N95 mask, gloves, and Tyvek coveralls if heavily infested). Look for droppings on insulation, runway smudges along beams, and gnawed material.
Check roof contact points from outside: any tree branch within 1 m of the roof, hydro lines from pole to house, adjacent fences or trellises tall enough to give vertical access.
Inspect the soffit-fascia junction with binoculars from the ground. Look for darkened gaps, gnaw marks on fascia, and any visible holes.

Why baiting alone fails on roof rats

Roof rats can travel several blocks along contiguous tree canopy. If the entry point at your home stays open, baiting kills the current population only to be recolonized within 2-4 weeks from neighbouring properties. The exclusion has to come first — close the entry, then suppress what's already inside. Most of our North Shore inspections find 2-3 active entry points per home, all within 5 m of each other along the roof line.

Frequently asked questions

Are roof rats dangerous to humans?+

Direct attacks are extraordinarily rare. The risks are indirect: contaminated droppings (hantavirus, salmonella, leptospirosis), structural damage from gnawed wiring or vapour barriers, and contamination of insulation. None are emergencies, but all justify acting within a week of confirming activity.

Will they go away on their own when warmer weather comes?+

No. Once roof rats establish in an attic, they treat it as permanent territory. Spring and summer might reduce indoor activity slightly, but the population persists year-round in BC's mild climate. The seasonal 'reset' that colder Canadian cities experience does not happen in Metro Vancouver.

Can I just trim the trees and they'll leave?+

Trimming canopy is a necessary part of roof rat exclusion but not sufficient — roof rats have already entered via the canopy, and the entry points stay open even after trimming. The full sequence is: trim canopy, seal entry points, deploy traps in the attic, monitor for 6-8 weeks.

How do I find a contractor for the structural sealing?+

Pest companies licensed under the BC Integrated Pest Management Act handle both the rodent suppression and the structural exclusion. We do all of it as a single job. Avoid generic 'handyman' fixes — improper material choice (caulk instead of hardware cloth) means the work needs redoing within a year.

Attic insulation: when contamination forces replacement

Blown-in mineral wool or cellulose insulation that has been contaminated by roof rats is not salvageable through spot-cleaning. Rat urine saturates the fibres and the ammonia smell persists even after the population is eliminated. Rodent-contaminated attic insulation in Metro Vancouver homes is also a fire risk if rats have gnawed through wiring that runs through the insulation. The remediation sequence: eliminate the population first (exclusion + traps + 6-week monitoring to zero activity), then remove and replace the insulation. Doing it in the wrong order means you're replacing insulation while rats are still active — the new insulation gets re-contaminated. Expect $3,000-$8,000 for full attic insulation replacement in a typical 2,000 sq ft North Shore home depending on depth and access.

Cedar shake roofs and the North Shore rat problem

Cedar shake roofs are beautiful and common throughout North Vancouver, West Vancouver, and the Burnaby Heights heritage corridors. They are also structurally ideal for roof rat access. As shakes age, they cup and lift at the edges, creating entry gaps under the ridge cap and at the eave line. Moss and algae growth further lifts the shakes. The shake-over-skip-sheathing construction method used on older North Shore homes leaves air gaps between the shakes and the substrate — these become rat runways. Treating the rodent population without addressing the roof substrate is a short-term fix: the shakes re-lift within a season. The permanent answer usually involves a combination of exclusion sealing at the fascia and soffit level plus canopy trimming, with periodic roof maintenance to re-bed lifted shakes.