The properly built shed with a wood floor is constructed with the bottom of the floor about 4 inches off of the ground. It’s done this way to have proper air circulation under the floor which keeps the floor dry.
This space can also provide a nesting home for animals.
If you block the air space under your wood floor trying to keep out the little critters, you will stop the air circulation and condensation will be trapped and your floor will rot sooner then later.
The best method to keep small animals from setting up house under your shed is installing a wire screen around the perimeter. This will keep the animals out and let the air in.
Dig a 6 inch trench around the perimeter of your shed as close to the shed as you can. Measure the distance between the bottom of your siding to the bottom of the trench. This will be the height of your wire screen. You can buy the screen at your local home improvement store like Home Depot. It comes in rolls about 48 inches high and 25 feet long.
The most difficult part of this operation is cutting the wire screen. You can use a circular saw but be really careful. Leave the screen in the roll, measure then cut. Little pieces of the screen may shoot at you when you are cutting. Wear safety goggles or glasses. If you don’t like to take chances, use a wire cutter or tin snip. Unroll the screen and cut it to the height required. This is a two person job and be careful of the sharp edges.
Start installing the screen at the front left side of your shed. Bring it around the front and down the right hand side. The best way to fasten the screen is with an air powered roof staple gun. If you don’t have one of those, you can use any type of galvanized fastener, like a heavy wire staple etc… you can find at Home Depot Etc.
After you have it secured to the building, tuck it down into the trench and back fill. If you would like to really dress it up you can buy vinyl lattice. Cut it to size and screw it in. Use galvanized or stainless screws.
This method should pass any code that requires this and will keep out any animal, just be careful when cutting the wire screen.