The rowhouse roof is one building for a squirrel
Philadelphia's defining housing type is also its defining squirrel problem. Rowhouses share a continuous roof plane and party walls, so from an animal's point of view your block is a single long structure with many possible doors. That has two consequences. The first is that an entry you cannot find may not be on your house at all. A gnawed opening in a neighbor's cornice return gives access to a run that leads straight over your ceiling. The second is that sealing in isolation frequently fails. Close your own openings and the animals simply keep using the ones next door, and the noise reappears in a different room. The practical answer is to scope the work across the run rather than the deed line. Ask the inspector to walk the whole roof, not just your section, and to tell you which openings are yours. Then talk to the neighbors before scheduling. Coordinated work costs each household less than a sequence of separate visits chasing the same animals from house to house.
Why winter colonies here do not break up
Homeowners often assume a nocturnal group will disperse once spring arrives. Flying squirrels do not follow that script. Their litters run two to four young twice a year, and the young may remain with the mother through winter, so what starts as one female becomes a small resident group that stays put. That is why single removals disappoint. Catch one animal in January and the ceiling stays busy, because the rest of the group is still there. It also explains why people describe the noise as light and scattered rather than heavy: several small animals moving is a different sound from one gray squirrel crossing a joist. In Philadelphia, winter lows near 26F make an old insulated attic worth defending, and rowhouses offer plenty of them. The plan that works is repeated removal or a large exclusion device covering the full entry area, plus a careful hunt for secondary openings, since flying squirrels use gaps a fox squirrel could never fit through. Ask whether a quote is written for one animal or for a group.
What Pennsylvania rules let you do
The state's position is more permissive than many people expect. Fox and gray squirrels are game animals in Pennsylvania, but a landowner may act on squirrels destroying property without holding a hunting license. In other words, you are not obliged to wait for a season to protect your own building. That freedom has limits worth understanding. It applies to your property, not to work performed for pay on someone else's, which is licensed nuisance wildlife activity. So when you compare companies, the license question is a fair one and a professional will answer it without hesitation. The rule that catches people out is what happens next. Trapping an animal raises the question of where it goes, and states restrict relocation in ways that surprise homeowners. Rather than untangle that on your own, most Philadelphia situations are better handled with a one way door, which removes the animal without ever putting it in a cage and sidesteps the entire question of what to do with it afterward.
Where the openings are on an old Philadelphia roof
Forget the suburban picture of a chewed soffit. On a rowhouse the entries cluster in a handful of specific places, and knowing them shortens the search. Cornice returns come first. Decorative woodwork with a hollow interior gives an animal both a cavity and a soft edge, and a century of weather has usually opened a seam somewhere. Parapet joints are next, especially where the coping has shifted or the pointing has failed. After that, look at the roof hatch curb, the flashing around vent stacks, and any place a rear addition or ell meets the main roof at a different height. Every one of those is also a place water gets in. With 47 inches of rain a year and an elevation of only 39 feet, drainage is a constant problem on flat roofs here, and the same joint that leaks in March is the joint an animal widens in December. When you get an inspection, ask for both lists: what is chewed, and what is simply failing. They usually overlap.
What moves the price on a Philadelphia job
Access is the first thing to look at. Getting to a third floor cornice on a rowhouse is not the same as leaning a ladder against a two story house, and how a company reaches the work is a real cost whether or not the quote itemizes it. The opening count is second, and on a shared roof it can be higher than you expect. Third is the nature of the repair: screening a vent is inexpensive, rebuilding a rotted cornice return is carpentry. Fourth is the animal. A flying squirrel group means several visits rather than one door and one return trip. Then there is cleanup. Soiled insulation does not recover, and with winter lows around 26F the lost value is a heating cost every month until it is replaced. Ask for removal, sealing, and cleanup as separate lines. In a city where median home values sit near $225,000, a few hundred dollars of proper metal work is cheap next to rebuilding a ceiling and rewiring an attic.
Sorting the species by what you hear
You can usually name the animal before anyone climbs to the roof, just by paying attention to two things: the hour and the weight. Activity that peaks at sunrise and again in late afternoon, with heavy footfalls that sound like something rolling, means gray or fox squirrels. These are daytime animals, generally one adult holding a den, and the case a single one way door handles well. Sharp, fast, very loud noise for the apparent size of the animal, along with shredded insulation and cached material in a wall cavity, points to red squirrels. They fit through smaller openings than grays, so the inspection has to look beyond the obvious gaps. Strictly nocturnal noise, lighter and scattered across the ceiling, means flying squirrels. Penn State Extension counts both southern and northern flying squirrels among Pennsylvania's five tree squirrel species. Write down the times you hear movement over three or four nights and bring that list to the inspection. It is the single most useful thing a homeowner can supply.