Wildlife Exclusion

Wildlife Exclusion for New York Homes: Sealing Every Entry Point Permanently

February 28, 2025·11 min read

Wildlife exclusion is the process of permanently sealing a structure against animal intrusion. It is the single most important wildlife management service available to New York homeowners — and it is routinely undervalued relative to trapping. Trapping removes an individual animal; exclusion removes the entry opportunity permanently. Without exclusion, every gap in your roofline is an advertisement for every raccoon, squirrel, bat, and opossum in your neighborhood.

Why Trapping Alone Fails New York Homeowners

Trapping is a short-term intervention. It removes the specific animal currently in your home but does nothing about the entry point that animal used, the scent signals left behind that attract the next animal, or the structural vulnerabilities that will be exploited repeatedly. In suburban New York — where raccoon and squirrel population densities are among the highest in the northeastern United States — an unsealed entry point is virtually guaranteed to be reused within days to weeks.

A trap-only approach also creates a cycle: each new animal occupying an attic deposits fresh scent, urine, and feces that reinforce the attractiveness of the site to future animals. After several seasons of unaddressed trapping, an attic can become so thoroughly scent-marked that it functions as a beacon for wildlife across a wide territory. Full exclusion plus remediation breaks this cycle.

The Four Categories of Wildlife Entry Points

1. Roofline Vulnerabilities

The most common wildlife entry points in New York homes are at roofline transitions — the junctions between different roofing materials and architectural elements where sealing is difficult and maintenance is neglected:

• Fascia boards: The horizontal boards running along the lower edge of the roof where the gutters attach. When fascia boards rot (common in older Nassau County and Westchester homes with wood-trim construction), they create a gap between the fascia and the soffit that provides direct attic access for raccoons and squirrels.
• Soffit panels: The horizontal panels under the eave overhang. Vinyl or aluminum soffits can be pushed aside by raccoons; wooden soffits rot; aluminum soffit vents can be bent or removed by persistent animals.
• Roof-to-wall junctions: Where a flat or low-slope section of roof meets a vertical wall, the step flashing and counterflashing can separate over time, creating gaps that bats and squirrels exploit.
• Ridge caps: The material covering the peak of the roof often gaps at the ends where it meets a gable wall — a common flying squirrel entry point.

2. Chimneys

Uncapped masonry chimneys are the second most common wildlife entry point in New York homes. Raccoons, squirrels, and bats all use chimneys. The appropriate solution is a properly rated chimney cap:

• Stainless steel or galvanized steel, not aluminum (raccoons can open aluminum caps).
• Solid screen mesh on the sides (not open-sided spark arrestors that can be opened by raccoon paws).
• Proper fit with no gaps at the crown — an improperly sized cap leaves gaps that bats can access.
• For bat exclusion specifically, ¼-inch or finer mesh is required on the cap sides.

3. Roof Penetrations and Vents

Every pipe, wire, and HVAC component that penetrates the roof creates a potential entry point:

• Plumbing vent stacks: Often have gaps around the pipe where it penetrates the roof deck — these are sealed with roof cement and metal collars, but deteriorated sealant creates openings.
• Gable vents: The triangular vents at the ends of gable roofs are a primary target for squirrels. Many older homes have wooden louvered gable vents with no screening at all behind the louvers. Retrofit with 16-gauge ½-inch hardware cloth installed behind or over the vent.
• Roof-mounted HVAC components: Gaps around flashing for rooftop HVAC units are a common raccoon and squirrel entry point on flat-roofed commercial and NYC rowhouse structures.

4. Foundation and Ground-Level Points

Skunks, groundhogs, and opossums primarily enter structures at ground level. Foundation exclusion requires a different approach than roofline work:

• Crawlspace vents: Replace damaged or absent screening with 16-gauge galvanized hardware cloth. Ensure the frame is intact and secured to prevent leverage attacks from groundhogs.
• Deck perimeters: Install L-footer exclusion (hardware cloth bent at 90 degrees and buried 12 inches horizontally underground at the base of the fence) around all deck and porch perimeters.
• Foundation gaps: Cracks in block or poured concrete foundations that are ½ inch or larger should be filled with concrete mortar or hydraulic cement. Steel wool packed into gaps before mortar application prevents re-excavation by determined animals.

Materials That Work vs. Materials That Fail

The longevity of an exclusion depends almost entirely on material selection:

The Exclusion Process Timeline

A full exclusion project on a typical Long Island or Westchester home proceeds in three stages:

1. Inspection and assessment (Day 1): Full exterior perimeter walk with binoculars, roof access, and attic inspection. All entry points identified and documented. Presence of animals confirmed or ruled out.
2. Active eviction (Days 1–10): One-way exclusion devices installed at primary active entries. All secondary entry points sealed permanently. Animals allowed to exit through one-way devices over 5–7 days.
3. Final sealing (Day 10–14): One-way devices removed and primary entries permanently sealed with appropriate steel materials. Full perimeter re-inspection to confirm no missed gaps.

Frequently Asked Questions