The screech of someone who just saw a rat or a mouse is sometimes humorous and is a clear sign of an space invasion. However, with most calls that I get the homeowner has not actually seen the rat, they tell me of EVIDENCE they have that points to an invasion. Sound: they hear rats scurrying in the walls and attic/ceiling. Sight: they have seen droppings in areas or they have seen their pets behaving weird. Smell: yes, there is a certain smell that is unmistakable in small, enclosed areas.
First point is under doors and in the corner of garage doors. Turn off the interior lights during the daytime and look for sunlight shining through... if you can see light, its worth looking closer at. 1/4 of an inch is all a mouse needs and 1/2" is all a rat needs to gain entry.
The picture at right was taken at an office. I can only imagine what the hole was drilled for but in the end it was left wide open. This is not as common in residential properties because the homeowners double check the work done and would notice a 2.5" hole left open. Commercial properties, check the quality of work being done!
As you look close at the picture, you can see the most common tell-tale sign of rodent activity. I outlined the grease rub marks left by rats coming and going as they please. I should note here that someone may have noticed this hole at some point but figured it was high enough off the ground... not so. Rats can elongate their body.
Roof rats can jump around 18 inches and even further when jumping down. This is why trimming trees and bushes is a crucial part to rat exclusion.
Roofs have multiple potential access points. Most that I discover are from poor construction practices that leave large gaps in the eves and where different roof angles intercept. These can be next to impossible to see until you take a flashlight and look close (less that 18 inches away). Some are even impossible to see and will need to be felt... yes, like sticking a (gloved!) hand in to see if there are any gaps.
The picture below with the tiled roof shows a very common problem. Open ends... this is welcome to rats, birds, bats... you name it. The best solution to this is prevention... a quality roofer will give the customer an option for a piece that goes in during install. There are other ways to seal after the install, but none come close to just doing it right the first time. Items like attic vents are often time secured in a way that prevents water from coming in, but a determined rodent can easily go up underneath the lower metal flange or a corner.
- It's old and deteriorated
- It was accidentally bumped by outdoor equipment or furniture
- Kicked in while playing (ie. soccer) in the yard
- It was cut, removed or altered to run cable, wiring or pipes