Exterminators get rid of rats in walls through a multi-step process: locating the nests and entry points, setting traps in strategic positions, sealing every gap the rats used to get in, and cleaning up the contamination left behind. The whole process typically takes multiple visits over one to several weeks, depending on the size of the infestation. Here’s what actually happens at each stage.
Finding Rats Behind the Walls
Before anything else, a professional needs to figure out exactly where the rats are and how they got in. This starts with a visual inspection of the home’s exterior and interior, looking for droppings, grease marks along baseboards, gnaw marks, and small holes or gaps. Rats can squeeze through openings as small as a quarter, so exterminators check areas most homeowners overlook: where pipes and wires enter the house, gaps around dryer vents, deteriorating weatherstripping around garage doors, and cracks in the foundation.
For rats hiding deep inside wall cavities, many professionals now use thermal imaging cameras. These detect temperature differences on the surface of a wall caused by something on the other side. A rodent nest that’s been generating body heat for days or weeks can warm the wall enough to show up on a thermal camera. Even without a visible heat signature from the nest itself, thermal imaging can reveal irregular patterns like cold spots where rats have displaced insulation or moisture damage from gnawing on pipes. Because rats are nocturnal, thermal cameras also let exterminators track their movement in complete darkness, mapping the routes rats use to travel between walls and food sources.
Some exterminators also use borescopes, which are thin flexible cameras that can be inserted through a small drilled hole to see directly inside a wall cavity. This avoids cutting open large sections of drywall just to confirm a nest location.
Trapping and Removal
Once the exterminator knows where the rats are active, trapping is the primary method for removing them. Poison bait is generally avoided for rats inside walls because a poisoned rat often crawls deeper into the wall cavity before dying, creating a much harder problem to solve later (more on that below).
Instead, professionals place snap traps or electronic traps along the rats’ travel routes. Rats are creatures of habit and tend to follow the same paths repeatedly, usually along walls and edges. Exterminators position traps at entry points where rats move between the wall void and living spaces, in attics or crawl spaces connected to the wall cavities, and near any access points they can identify. The traps are baited with high-fat, high-protein foods like peanut butter or dried fruit, and checked regularly over the following days.
For wall cavities that are difficult to access, some professionals install one-way exclusion doors at the entry point. These are small funnel-shaped devices that allow rats to push their way out of the wall but prevent them from getting back in. Once a one-way door is installed and all other entry points are sealed, the rats are forced to leave on their own and can then be trapped outside the wall. This approach avoids cutting into drywall and works well when the entry point is clearly identified, like a damaged wall vent or a gap around plumbing.
Sealing Entry Points
Trapping alone won’t solve the problem if new rats can still get in. Exclusion, the process of sealing every possible entry point, is arguably the most important step. Exterminators use steel wool, metal flashing, hardware cloth, or specialized sealants that rats can’t gnaw through. Standard caulk or foam insulation won’t hold up; rats chew through soft materials easily.
Common entry points that get sealed include gaps around utility lines, cracks in the foundation, damaged soffit or fascia boards, uncovered roof vents, and spaces where the roofline meets the walls. A thorough exclusion job addresses every opening larger than about half an inch. This is often the most labor-intensive part of the process and a big part of what you’re paying for.
Dealing With Dead Rats in Walls
If a rat dies inside a wall, whether from poison, a trap, or natural causes, the smell becomes unmistakable within a day or two. Locating the exact spot is tricky. The odor helps narrow the general area, but pinpointing the carcass often requires cutting into the drywall. Some exterminators use thermal cameras or simply follow the strongest concentration of the smell, tapping along the wall to find hollow spots near the source.
Once the section of wall is opened, the carcass is removed and the area is cleaned and disinfected. According to Orkin, there is no chemical that reliably eliminates the odor of a dead rodent. If the carcass can’t be reached, the smell will persist for roughly 10 days, sometimes a bit longer, until decomposition is complete. This is one of the main reasons professionals prefer trapping over poison for rats already living in walls: a trapped rat is recovered immediately, while a poisoned one can die anywhere.
Cleanup and Restoration
After the rats are gone and the entry points are sealed, the contamination they left behind still needs attention. Rat droppings, urine, and nesting material can harbor bacteria and parasites. Exterminators or specialized remediation crews remove soiled insulation, vacuum droppings using HEPA-filtered equipment, and apply antimicrobial treatments to affected areas. In severe cases where rats nested in wall insulation for weeks or months, the insulation may need full replacement.
This step matters not just for health reasons but because the scent of a previous infestation attracts new rats. Pheromones in urine act as a signal to other rodents that the space is habitable. Thorough decontamination removes that chemical invitation.
What It Costs
The price depends heavily on severity. A minor infestation involving basic trapping and a few sealed entry points typically runs $150 to $350. Moderate infestations that require multiple visits, extensive sealing, and sanitation fall in the $350 to $750 range. Severe infestations, especially those involving contaminated attic or crawl space insulation, structural damage, or drywall repair, can run $750 to $2,000 or more.
A standard rat extermination service without major complications typically costs $200 to $600. If roof rats have nested in attics or wall cavities and damaged insulation, expect the higher end of that range or beyond, particularly once insulation replacement and structural repairs are factored in. Most exterminators offer a follow-up visit or warranty period to confirm the rats haven’t returned.
How Long the Process Takes
A simple case with a small number of rats and obvious entry points can be resolved in one to two weeks across two or three visits. The first visit covers inspection, trap placement, and initial exclusion work. Follow-up visits check traps, remove captured rats, and finish sealing any remaining gaps. More complex infestations, particularly in older homes with numerous entry points or rats nesting in multiple wall cavities, can take three to four weeks. Cleanup and insulation replacement, if needed, add additional time after the rats themselves are gone.
Between visits, you may still hear scratching or scurrying in the walls. This doesn’t necessarily mean the treatment isn’t working. Rats that are cut off from food sources and finding their usual paths blocked will become more active and noisy before they’re caught or forced out through exclusion devices.