The roof line is the highway
Overhanging branches, downpipes and pergolas give rodents a route to the roof. Once there, eave gaps, fascia junctions and roof-to-wall junctions provide entry into the roof void.
From the roof void, wall cavities and service penetrations lead down into the living areas. A rodent in the kitchen frequently entered at the roof.
Garage doors and service penetrations
Roller doors rarely seal at the perimeter. That gap, plus unsealed air-conditioning, plumbing and cabling penetrations, accounts for a large share of residential entry points.
These are cheap to address and easy to overlook, because nobody looks at the bottom corner of a garage door until there is a problem.
Why sealing must not break the building
Subfloor vents and weep holes exist to let moisture out. Screening them requires purpose-made mesh that maintains airflow and drainage. Blocking them trades a rodent problem for a damp and decay problem.
The same applies to ventilation openings and to joints designed to move. Exclusion has to work with the building, not against it.
Treatment order matters
If rodents are already inside, seal the building after treatment. Sealing first traps them and tends to push activity deeper into cavities, where it is harder and more expensive to resolve.
Written by Accurate Building Inspections. This article is general information about property inspection in NSW and is not a building inspection, pest inspection, engineering assessment or legal advice. A visual inspection cannot guarantee the absence of concealed defects.