Always keep your doors closed. You may have the habit of keeping your door open, be it the front door, or the garage door. If you keep repeating that behaviour, mice get golden chance to enter your house. So since you truly want to live peacefully without any intrusion from mice, you need to keep the doors closed – always! No two ways about it!
At night, mice become hyper-active, so keeping your doors open during the night is a big disadvantage!
If you are a fan of summer breeze, you may get screen doors installed in your house. That way, you will be able to enjoy the breeze without having to worry about any kind of mice intrusion.
Have the windows sealed. As mice have no trouble climbing, keeping the windows open may prove to be a mistake as well. It is very common for mice to enter houses thorough windows, so your best bet is to either keep the windows closed, or use window screens.
Screens are prone to damage over time, and torn fabrics and rusty holes are common occurrences. Therefore, in case you have not checked the screens for a while, you need to go ahead and inspect each and every one very carefully in order to make sure that mice are not entering with the help of any screen hole or tear.
At times, you may find that a certain window does not get shut all the way, and that the part between the frame and the window contains a gap. If you spot such a window, have it sealed by using either hardware cloth or steel wool.
Check the foundation. It is quite possible for mice to make entry using cracks developed in walls, particularly cracks that are close to the doors or windows. Have a good walk all around the house to find out if any hole or crack is noticeable which can be a possible entryway for mice.
If a hole is any larger than 1/4th of an inch, or close to 6.4mm, it is time to have it sealed properly. Note that weak materials are pretty useless when it comes to sealing, since mice can easily chew such materials. The most rational thing you can do is use a sturdy material such as hardware cloth, concrete mortar, sheet metal etc.
Mice are truly cunning, and it is very common for mice to enter the house using the garage as the first stop. So be sure to nicely inspect the wall between your garage and the house.
Lock all the vents, chimneys and outlets. Given that a cable hole is large enough for a mouse, it is quite simple for it to enter your house using that hole as the highway. Mice can also enter using holes created for drains and pipes. Vents and chimneys are not immune to mice intrusion either.
Make use of pads made of stainless steel to stuff tiny holes or gaps around cables as well as pipes, and then use caulk to seal such holes. You can further trim a stainless steel pad to fit an area, and thus, create an abrasive barrier for mice.
Moreover, make it a point to make use of screens to keep mice from entering vents, chimneys and pipes.