There isn’t really a good or bad time to start looking for rat holes around your property. Rats will enter your home at any point of the year, especially if there are easy access points and you offer up plenty of food. Fall is a pretty decent season to start your efforts, just before rats, mice, and other pests start to look for indoor dwellings to help see them through the cold winter. Many of them, rats particularly, won’t survive a very cold winter if they don’t find a warm enough place, and they know it, too.
The more proactive you can be towards the end of summer/beginning of fall, the higher the chances of you preventing a rat infestation during the winter that follows.
The aim of the game is to prevent the rats from getting in at all, so you will obviously want to start your efforts on the outside of the building. You should also perform a thorough investigation of the inside, too. You would be amazed by how many holes are missed on the inside, just because homeowners aren’t aware there are even holes on the outside.
Windows and doors are a common place for rats to get in and out of your home. If you like to leave the back door open during the summer, you may wish to think again. Rats and other rodents/scavengers can get in and out of the building in the blink of an eye. You must remember that they are much smaller and much faster than you are, and probably the same for any pets you have in the building, too.
The areas around windows and doors can be hit. In fact, anything that breaks up a wall can soon start to show patches of damage, such as rotting wood, peeling away plastic, or even brickwork that has become old and rundown. Rats will chew through all of these materials, and then a few more besides. You should always check the areas around doors, windows, where plumbing or vents enter/exit the building, and also where the walls meet, the walls meet the floors or ceiling, the chimney, and where the roof meets roof/walls/chimney. It does sound like a lot of work, and it is, but that’s why you can hire someone to do this for you!
Rats will use a channel of air to figure out how to get through a tight spot. So, for example, if they can sense that air is flowing through a tiny hole in the crumbling cement that holds bricks in place, they will chew and gnaw at that crumbling cement until they have made a bigger hole. More air will, obviously, flow through, and this gives the rats even more determination — air flow means a pathway and most pathways lead to somewhere … hopefully, food.
A rat needs a hole just three-quarters of an inch to get in. Any hole smaller than that will be chewed at until the hole is big enough to let them through. Rats will use holes that mice have made, and will also leave holes big enough for other, larger scavengers to them come through, such as skunks and opossums, and potentially even raccoons, too.
Aside from doors, windows, and where those and similar items break up solid walls, the foundations of a building should also be checked. The top and bottom of the home might seem like difficult areas for animals to reach, but they’re often the easiest. Rats can use branches and tree trunks to get higher, and they can jump quite a distance too — much more than you’d think. It doesn’t take very long for a rat to reach your roof, and even if they didn’t have those things, they can climb pretty well. Rats CAN climb up the brickwork on the exterior walls of buildings. They just can’t climb anything that has a smooth surface, that they can’t grab on to with paws and claws. If the surface is textured, they’ll have no problems at all.
On the inside of your building, matters get even more complicated. The inspection is likely to be a lengthy one, involving a thorough look-over of each and every room in your home. Starting from top to bottom (or vice verse), you must check every single room, floors, walls, ceilings, and everything else include. You should book for holes, but not just holes; you should also keep your eyes open for any sign that might point to a rat, or potential other pest animal invasion. This could be urine, feces, nesting or bedding material, chewed areas or teeth marks, clumps of fur, grease left behind by fur-rubbing, food remnants, or even dead carcasses. When you have rats, you usually have a population of tens, hundreds, or maybe even thousands of them. When you have a large number of animals in one space or group, it will only be a matter of time before you encounter a dead one.
Rat holes can appear in the weirdest of places, even places where you don’t rats can actually get to. Using the attic, foundations, wall cavities, crawl spaces, and plenty of other dark and seldom visited parts of your home, they can spread into each room, leaving damage and destruction in their wake.