Case Study Rat Burrow Under Bathtub in Caledonia

Case Study: Rat Burrow Under Bathtub in Caledonia

The following case study tells the story of a rat removal job in Toronto in which rats were burrowing underneath the bathtub. This article will analyze and recount a rat infestation case that required multiple visits and will detail the steps in the exclusion process that technicians took to eradicate the rat presence completely and successfully in a residential property in Caledonia, Toronto. Technicians go through several steps to conclude before moving on to the actual exclusion and the eventual sealing and proofing. We received a call from a property owner in Caledonia. The activity was heard under the bathtub in the basement.

Caledonia: Steeped in History

Caledonia-Fairbanks is an historic neighbourhood just located south from the ever construction-heavy Eglington St. The neighbourhood features a lot of inclines as it is located in the more northern parts of the city. The neighbourhood was historically an electric and vibrant mix of the Italian immigrants who presently left their mark in the neighbouring Italian enclave and neighbourhood of Corso Italia.
Houses, particularly in the Fairbanks-Caledonia date back to at least hundred years, if not more. This makes these houses very susceptible to intrusion and break-ins from several pests and wildlife animals that inhabit the region. Cracks in the foundation can form through wear and tear as well as several cracks, holes, and crevices throughout the exterior of the building. Another interesting tidbit about the neighbourhood is that it is closely located near the CNR lines which is a popular destination to thrive and spawn future generations far away from human interference. Older pipes leading to these houses in the neighbourhood gives rats an easier way to enter these buildings by following these disused pipes. A lot of these pipes very much connect to these historical neighbourhoods which rats can exploit to covertly enter and nest in the interior.

Exterior Inspection

Exterior Inspection Foundation Gap
Rats and other wildlife will take advantage of gaps in the foundation and beneath the walls of the home.

Signs of rat activity were heard under the basement floor bathtub. Live rat activity was also seen in the homeowner’s backyard which can indicate a heavy infestation in the area in general. Signs of a rodent infestation were also heard like pitter patter, gnawing, and rustling. As for rodents in general, such as for mice and rats, the exterior inspection remains more or less the same and is one of the most crucial steps to undertake in the entire exclusion process. The exterior inspection aims to seek out holes, cracks, crevices, and structural gaps located at the foundation of the house. Once these are located, the technician makes note of the areas and relays the information to the home owner who then is recommended to have them sealed as soon as possible by a third party or by the technicians performing the exterior inspection. Knowing where these entry-points are, is knowing where rodents are entering from and gives a very good idea of where they might be located in the exterior to be sealed and proofed later on during the exclusion process.
Structural faults are often found around houses situated in older neighbourhoods in a city. It is well known that Toronto’s settlement goes back at least to the 17th CE. Together with the ever-changing population, neighbourhoods began to sprawl into what are known as the present-day neighbourhoods.

Interior Inspection

Based on the homeowners reports, the technician conducted the interior inspection at the basement level. The interior inspection is also very important and is critical to find and detect rodent presence in the interior of the building. Finding an interior entry-point can pinpoint where the rodents are finding their way and prevent further spreading of the infestation. During the interior inspection, signs of activity is attentively looked for. Certain signs that are related to rat activity are, but not limited to droppings, rub marks along the walls, snippets of paper or cardboard, gnaw marks, bite marks, gnawed wiring. The reason why technicians are looking for these signs as a direct indication of active rat presence is because rodents have no control over their stools as well as have the habit of gnawing and biting as a way to keep their incisor teeth in check. Not keeping it in check can hamper their ability to function normally. Since rodents have to gnaw everyday, it is a great clue and lay droppings, it it is a great indicator Knowing how to differ from rat and mice droppings can confirm what rodent you are dealing with. Rat droppings are longer in length and have sharper ends on both sides. Mice droppings on the other side are smaller in size and said to be the size of the grain of rice or chocolate sprinkles.
Technicians found a grave case of live rat activity when they opened up the bathroom floor where the bathtub was located. They also found a rat burrow when they removed a portion of the drywall behind the bathtub. A rat burrow is a serious sign of a rat infestation spun out of control. When a burrow is found it is certain that several generations inhabit the area.

Initial Measures Taken

The measures that were taken against before tearing down the drywall are critical for getting the rat population out of the building before beginning the actual exclusion and proofing process. Snap-straps were strategically placed in order to capture the population inside the basement space while exterior bait-stations were used to lure and kill the rat population roaming around in the back yard. The snap-traps are specially designed taps to kill the rats in an instant. It is very effective for use indoors since it does not take up a lot of space. Exterior bait-stations are tamper-proof containers loaded with bait blocks. These bait blocks contain rodenticide which is very attractive to the rodents. The rodents smell these bait blocks and eat from it causing them to perish.
For the separate issue with the rats thought to be coming from the sides of the property near the extension of the house, a One-Way Door was placed and installed. A One-Way Door is a tunnel-like contraption that, once the rodents pass through it, it will be locked out. The rodent can enter the contraption but cannot re-enter the contraption because of its limited single-way entry-point. The rodent realizes this and is forced to vacate the property and go elsewhere. The results may require some patience on the customer’s end since the rodents will have to go outside to feed themselves eventually. Once they go outside and pass through the One-Way Door, they will not be able to get back in. Apart from installing and mounting the One-Way Door as pictured below, 24ft of galvanized steel mesh was mounted with washers and bolts to secure the perimeter of the house on the exterior.

Foundation Exclusion Rat One Way Door
Rats leave their nests every day to find food. The one-way door prevents their return by swinging out in only one direction. Once outside, they will consume the rodenticide placed on the exterior of the home.
Foundation Exclusion Rodent Proofing
Adding mesh to the bottom of the wall would prevent rats from digging underneath the house and into the indoor space.

Interior Exclusion

To get to the root of the problem, it was proposed that 18 inches along 14 feet were to be removed along the base of the drywall in the basement bathroom. To precisely know what affected areas to remove, technicians to used thermal imaging from a thermal camera to see where the affected area where. The thermal camera displays cold fronts by visually showing a fluctuation in temperature. The reason why the cold front has a different temperature is because rats will cause the insulation to deteriorate which shows up visually on the screen as an area with lower temperatures. Information from this visualization can be deduced that some external force must be at work to cause this drop in temperature.

Floor Exclusion Under Tub Rat Proof

As for the for the concrete base floor of the bath tub space 13.7 square feet were to be secured and proofed. The proofing happens after it is concluded that no rodent activity is taking place whereafter the technician can start the exclusion and proofing process of the building. To proof the building against intrusions a material is used known as galvanized steel mesh. Galvanized steel mesh is flexible enough to be cut and manipulated while being durable at the same time. The material can resist all kinds of weather conditions and seasonal changes. Besides that, galvanized steel mesh, can resist all sorts of attacks against pests looking to seek entry inside of the property through the use of brute force. Brute force can include scratching, gnawing, biting, pushing, ripping, or tearing.  Because the galvanized steel mesh is securely held in place with washers and bolts, the probability of wildlife animals ripping it off is very slim.

Floor Exclusion Under Tub with Mesh

The performed exclusion included removal of the drywall along the base and excluding and proofing the very base of the bathroom space where the bathtub was located since the rats were thought to come up from underneath the bath tub. As earlier mentioned before, galvanized steel mesh was used to secure 13.7 square feet, fastened and secured with bolts and washers.
18 inches along 14 feet of drywall was removed and disinfected. The disinfectants are in the form of fog and contain hospital grade formulations. This is to ensure that all of the disinfectants go through the pores of the material and stick to the surfaces of non-pours materials. Surfaces can be either classified as porous or non-porous. Non porous materials such as steel or plastic have no way possibility of letting anything enter in the form of liquid or gasses. On the other hand, there are porous materials such as woods, insulation, and other materials that allow liquid and gasses to pass through the pores of the material which makes the disinfectant fogging material highly effective in these kinds of areas.
Since rats rapidly breed and span multiple generations, they leave heaps of feces and urine behind causing the insulation material as well as the area that they used to breed to be highly toxic. Homeowners have to fork up a significant amount of money to have the insulation material replaced. Insulation material must be replaced after an infestation in order to ensure a healthy and safe environment.
Odours were neutralized that came from the carcasses of rats. Since rats have a very high water contents, the stench that can be diffused is unbearable. During decomposition, certain tissue breaks down due to the natural process which in turn creates this rancid and rotten smell. Many people who have smelled this smell have gone to discover rat presence in their own properties. To clean up the debris from the exclusion process, a specialized industry-grade HEPA Vacuum was used to trap allergen particles with the help of a HEPA filter.


The basement remains a popular destination for rats which goes in hand with their behavioral trait. Rats tend to avoid any types of interaction and adhere to a quite reclusive lifestyle. They prefer dark and quiet areas which also emulates their natural habitats outside in the  burrows they dig in many yards. Prevention is key in most rodent infestations. Rodents often search in places where food is abundance. Knowing what attracts them is knowing what keeps them away. Reports of any rodent activity was not reported after our visit.