Rodent Exclusion and Proofing in NYC

Sealing stops mice from using the openings you closed, but only if every route is found and the material holds. Mice already inside must be trapped or removed first, or they stay sealed in with you. Sealing without an inspection tends to miss gaps behind appliances, inside wall voids and around pipe sleeves.

Trapping and bait deal with the animals that are there. They do nothing about the openings, food and shelter that let new ones in. Where the entry route stays open, activity tends to return. That is why an inspection looks for how rodents are getting in, and why exclusion sits beside control rather than after it as an afterthought.

Materials rodents cannot chew through, matched to the opening. That usually means metal mesh or hardware cloth, sheet metal, and cement or masonry fillers for masonry gaps. Foam or plain caulk on its own is not enough because rodents chew it out. The right choice depends on what the opening is, what surrounds it and how it will be used.

Rats can use damaged drain or sewer lines, and gaps where pipes pass through walls and floors are a common way in. Coming up through a toilet is rare and usually points to a broken line. An inspection that looks at the lines and every pipe penetration is how you find out which applies to your building.

Usually because the way in was never closed, or because a neighboring unit or the basement keeps supplying new mice. Trapping removes the animals you have. It does not change the openings, the food access or the shared walls that brought them. Recurrence is a signal to inspect again, not to add more traps.

Basements and cellars sit at ground level and hold pipes, utility lines, older masonry, storage and access to trash areas. That combination gives rodents entry, shelter and food in one place. In many NYC buildings the cellar is also where shared utility runs connect to the upper floors, so activity below can show up as noise or droppings above.