Put on your gloves bring a rag for cleaning spills then visit the cracks and gaps you spotted along your siding.
Seal bottom of vinyl siding.
6 siding transitions by foundation often siding is not secured all along the bottom near the foundation.
Mice can climb under the siding and enter the home through an existing construction gap.
Vinyl siding does not fit tight inside j channels or corner posts you don t caulk them shut and there are voids behind the lap siding too.
Vinyl siding installs in pieces so gaps and overlaps.
If it s 3 4 or more i d concider removing the bottom row of siding and starter strip and install a piece of 1 x 6 vinyl lumber then a piece of z moulding then replace the starter strip with j moulding reinstall the siding.
Vinyl siding starter strips snap a level chalk line for the first starter strip at the base of the wall no less than 8 inches above ground level after determining the lowest corner of the house.
Grass and mulch along the foundation provides habitat for mice.
On the other hand what may help is sealing you sheathing plywood osb to the foundation.
The bottom row of siding should sit flush against some form of backing.
There are professional materials that can be utilized to secure these areas on a home.
Each one has its own vulnerabilities.
Caulking is not usually the solution to a mouse problem.
Bottom line is you don t caulk places where water needs to weep out.
Although vinyl is impervious to water when installed as directed by the manufacturer vinyl siding as a whole is not completely watertight.
There are 3 main types of siding.
Wood vinyl and aluminum.
This is where the new siding will begin.
Simply apply this inexpensive filler into the cracks to seal.
You will want to stick your fingers behind the bottom row of siding and run them along the entire perimeter of the home.
This would 100 seal up theair leaks and cover all the gaps where critters can get in.