Guildwood Village Locksmith Pros · Toronto
Deadbolt Installation: getting ready
Locksmith · Toronto, Ontario

The back door has a deadbolt in name only: a short bolt, a thin brass strike held by two little screws, and a jamb you can flex with your palm. It was fine for a builder's showing. It is not fine for a laneway.
Worth answering before the call
Has the door or frame ever been forced, or are any screw holes stripped? Is there a storm door or screen door in the same opening? Have you already bought the hardware, and if so which model and does the template come with it?
Will drilling a new deadbolt damage my steel or fibreglass door?
Not when it is done for that door. Steel-clad doors are cut with a fine-toothed hole saw run slowly through the skin, guided by a jig so the saw cannot skate on the smooth face, and finished from both sides so each skin stays clean. Fibreglass is scored first so the surface does not chip. Shavings are vacuumed from the foam core, and the edge is finished with a collar or plate suited to the stile inside.
Does the finish of the deadbolt matter beyond looks?
It does on an exposed door. Winter salt spray, summer sun and humid air all work on the outside trim, and residential deadbolts carry a finish grade that reflects how well the coating resists them. A lifetime or PVD-style finish stays bright longer on a south-facing or roadside door, while a sheltered porch door can carry any finish you like. Matching the knob or lever below is mostly a matter of taste.