Bellingham Fall Rodent Prevention Checklist: Complete Before October

The Complete Checklist

1. Inspect crawlspace vent screens This is the single highest-impact item on the list for Columbia, Lettered Streets, Whatcom Falls area, and Birchwood homes. Get a flashlight and check each vent screen from the outside, press gently on the screen material. Original aluminum from the 1950s through 1970s often looks intact from a distance but is corroded and structurally failed at the frame joint. Any screen that flexes inward when pressed, has visible corrosion, or has gaps at the corners needs replacement before October. Replacement vent covers with galvanized steel quarter-inch mesh are available at local hardware stores or we can replace them as part of an inspection service.
2. Walk the foundation perimeter with a flashlight at grade level Bring the flashlight to ground level and look along the foundation-to-sill plate interface. A gap that’s invisible standing up is visible at the right angle. Pay particular attention to the corners of the foundation and to sections where the grade has settled away from the foundation wall, which can expose the sill plate connection. Any gap where you can see light from the crawlspace side warrants sealing before October.
3. Check and seal utility penetrations Walk the perimeter and find every point where a pipe, conduit, or cable enters the foundation. Gas line. Water supply. Electrical conduit. Cable/internet service entry. Each one should have a visible, tight seal around it. If you can see daylight around the pipe, or if the gap around it is larger than a quarter inch, it’s a Norway rat entry point. Copper mesh packed tightly around the pipe and covered with exterior caulk is the appropriate seal.
4. Inspect and replace door sweeps on all exterior doors The gap under an exterior door with a deteriorated sweep is a house mouse entry point that’s easier to address than any crawlspace work. Push a quarter, 24mm diameter, under each exterior door threshold. If it slides under without resistance, the sweep needs replacement. Standard door sweep brushes available at hardware stores; door thresholds with integrated sweeps provide better coverage on uneven concrete.
5. Trim branches to three feet from the roofline For Fairhaven, South Hill, and Edgemoor homeowners: check every tree adjacent to the structure and trim any branch that comes within three feet of the roof, eaves, or utility lines attached to the home. A roof rat can leap a three-foot gap. Branches touching the roofline are a direct bridge. September is appropriate for most Pacific Northwest tree trimming before winter.
6. Check gutter condition and downspout direction Clogged gutters that overflow along the foundation create the saturated soil conditions that attract Norway rat burrowing. Make sure gutters are clear before fall rains begin. Downspouts should discharge at least three feet from the foundation, extend them if necessary with splash guards or buried pipe. The grade around the foundation should slope away from the structure; if it slopes toward the house, water management is a contributing factor to rat pressure.
7. Inspect the garage perimeter The bottom seal of the roll-up garage door is the most commonly ignored entry point in Bellingham garages. Measure the gap when the door is closed, anything over half an inch needs a new bottom seal. Check the gap under the service door (the person-sized door into the garage) as well. Also check the corners of the garage walls where they meet the slab, common Norway rat entry points in garages where the slab has settled away from the wall.
8. Assess vegetation touching the foundation Plants, shrubs, and vines growing against the foundation create cover harborage that mice and rats use as a staging area before entering the structure. Washington State licensed pest inspectors recommend maintaining at least one foot of clearance between any vegetation and the exterior of the home. Trim back any shrubs or ground cover that contacts the siding or foundation.
9. Secure compost and bird feeders Compost bins without secure lids, and bird feeders left full overnight, are major fall rodent attractants in Bellingham’s neighborhoods. Secure compost with a solid-bottom bin or a bin with a tight-fitting lid. Remove bird feeders from positions directly adjacent to the house in October and November, or use tube feeders that minimize spilled seed on the ground. Chicken feed should be stored in metal containers with tight-fitting lids.
10. Install a plastic vapor barrier in the crawlspace if you don’t have one A crawlspace with bare soil in Bellingham maintains humidity levels that attract Norway rats and accelerate wood rot simultaneously. If you haven’t done this and you’re in a high-pressure neighborhood, Columbia, Lettered Streets, Birchwood, installing a 6-mil polyethylene vapor barrier over all bare soil before October is one of the most cost-effective preventive investments you can make. It’s a DIY project for a handy homeowner; we install them as part of crawlspace remediation work.
11. Remove scrap wood, cardboard, and stored debris from the crawlspace Old form boards on concrete piers, cardboard boxes stored in the crawlspace, scrap lumber, insulation scraps, all of these provide nesting material and harborage for Norway rats establishing in a Bellingham crawlspace. Remove everything that isn’t a permanent structural component.
12. Schedule a professional inspection if you haven’t had one If you haven’t had a professional inspection of your crawlspace within the last three years, September is the right time. A free inspection identifies every entry point before the October pressure season begins. Most exclusion work can be completed within a week of the inspection, well before November’s flooding rain. Pre-season inspection slots in high-pressure neighborhoods fill by mid-September. Call early.

Frequently Asked Questions