Why traps alone never finish the job
Trapping and sealing answer two different questions. Trapping asks how many animals are inside right now. Sealing asks whether there will be more next month. Doing only the first is why people describe rodent problems as endless. The threshold the CDC sets is a quarter of an inch, pencil width. That rules out most of what gets reached for first. Expanding foam is chewed through in a night. Caulk fails at the first attempt. Loose steel wool pulls out. What holds is hardware cloth, sheet metal, mortar and a metal door sweep, fitted so there is nothing to grip. The reason exclusion takes hours instead of minutes is the sheer count of qualifying gaps in an ordinary house: the gas line entry, the seam where the sill plate meets the foundation, the dryer vent flap, the corner where a porch roof meets siding, the bottom of a garage service door worn away by forty winters. Here is the useful test. After the work is done, someone should be able to walk you around the building and point at each closure and name the material. If nobody can do that, the sealing line on the invoice did not describe real work.
The detached garage is half the problem
Most rodent plans stop at the house, and in Detroit, where alleys and detached garages are the norm, that leaves the better habitat untouched. A garage gives an animal everything a burrow lacks: a roof, stored cardboard to shred, bags of seed and pet food on a low shelf, and a slab edge that has separated from the soil just enough to slip under. It is unheated, but it is dry, and in a climate that drops toward 18F it is a considerable upgrade over open ground. Work it as a second building rather than an afterthought. The service door needs a metal sweep, the slab edge and any frost heave gaps need closing, stored feed needs hard containers, and the pile of lumber or tires against the back wall needs to come off the ground. Alley bins matter too, since a Norway rat foraging a few hundred feet treats your garage and the neighbor's bin as one address. If you only have the budget for one building this year, seal the house first and clear the garage of food and cover. That combination costs almost nothing and takes away the reason for the traffic in between.
Older houses, thin budgets, and where the money goes
In a housing market where the median value sits near $85,000, spending several thousand dollars on pest work is a real decision, so it is worth knowing which parts of the job carry the value. The highest return per dollar is almost always at grade: door sweeps, the sill plate seam, foundation vent screens, and utility penetrations. These are the routes an animal finds first because it is walking a wall, not climbing one, and the materials are inexpensive. The labor is what you pay for, and it is worth paying for because thoroughness is the entire point. The next tier is sanitation and cover removal, which costs mostly effort: seed and pet food into hard containers, stacked material off the ground, ground cover cut back from the foundation. The lowest return is a recurring bait station program with no repairs attached. It reduces numbers while it runs and changes nothing about the building, so the cost never ends. In an older Detroit house with a block foundation, the same money spent once on metal and mortar keeps working after the crew has gone.
Renting, reporting, and getting the repair scheduled
If you rent, the parts of this job that actually end the problem are not yours to do. Vent screens, door sweeps, sealed penetrations and foundation patching all belong to whoever owns the building, so your use is a clear record rather than a better trap. Write down what you find and when. Photograph droppings with a visible date, note the room and the time of night you hear activity, and keep copies of every message you send about it. A dated sequence is far harder to set aside than a phone call, and it establishes when the problem was first reported. Be specific in what you ask for. Instead of asking for an exterminator, ask for the openings at ground level to be inspected and closed with metal, for the garage door bottom to be checked, and for the trash enclosure to be secured. Naming the repair moves the conversation past whether traps were set. The things you can control still help. Keep food in hard containers, take trash out promptly rather than storing bags indoors, and keep your own traps set along walls. That reduces the population while the structural work gets scheduled.
Comparing two proposals without guessing
Rodent proposals often look alike on paper and describe very different amounts of work. Compare scope first, price second. Begin with the repairs. Does the proposal itemize openings and materials, or does it list exclusion as a single line. Only an itemized scope can be checked once the crew leaves, and only an itemized scope changes anything permanent. Then look at the follow-up. How many return visits are included, what triggers an additional charge, and what the provider does if you hear activity again in six weeks. A trapping plan without return dates on it is a guess dressed up as a service. Third, look outside and next door. If there are burrows in the yard or a shared alley bin, an interior-only plan cannot hold. Ask whether rodenticide is part of the plan, where it would be placed, and how pets and non-target animals are protected from it. Also ask whether the detached garage is inside the price, because in this city that single question can separate two quotes more than any other line item. The cheaper number is frequently the one that quietly leaves a whole building out of scope.