Add the 5 1 4 inch thickness of the wall to the 12 inches.
Find wall stud under siding.
You should feel when it goes into the stud.
It s less effective on lath plaster walls but some have a metal scanning feature that may locate the nails securing the lath to the studs.
If you don t find signs of a stud 16 inches from the first one measure 24 inches from the first stud and look again there.
From the outside hook the tape measure over the outside wall corner and measure in 17 1 4 inches and you should find a stud.
The box is attached to a stud on one side.
If there are no gaps use a long thin nail and nail it about 1 2 from the edge of the box on each side into the wall.
If you have drywall walls a stud finder locates studs quickly and accurately.
Anxiously trying to find a wall stud while you re in the process of hanging a picture shelf or tv mount.
Drive a small nail into the wall where you believe you have found a stud.
The cover plate should cover the nail holes.
Adjust wall thickness measurements accordingly for thicker walls.
Oh i just need to find a stud to hang this picture and fifteen holes later you re convinced the wall is held up by pixie dust and a wish because apparently there s no wood behind it.
Mark when you hit the stud and transfer that to the outside.
Add another 1 2 inch for the boxing and 3 4 inch for standard lap siding.