Deadbolt Installation: what to note first

The door from the garage into the kitchen closes on a passage knob with no lock at all. Anyone who opens the garage is one turn of a handle from the house, and the insurance renewal form has a question about exactly that.

Worth answering before the call

Does anyone in the household have trouble with small knobs or stiff thumb-turns? Do you want the new deadbolt to work on the same key as your other doors? Does the door have to be pulled or lifted before it latches or locks at the moment?

Can a deadbolt be added to a door that only has a knob?

Yes, on nearly any wood, steel-clad or fibreglass entry door. The locksmith marks a spot above the knob, clamps a jig to the door and bores a cross hole through the face and a smaller hole through the edge, then cuts a pocket and fits a strike on the frame. The main things checked first are the door's thickness, what is inside it at that height and whether glass sits close by.

Should I choose a single-cylinder or a double-cylinder deadbolt?

For any door people leave the house through, a single cylinder with an inside thumb-turn is the sensible choice, and provincial building rules for dwellings call for exit doors that open from inside without a key. Double-cylinder bolts are keyed on both faces and are sometimes proposed where glass is near the lock, but a captive thumb-turn, laminated glass, or a tested security-film system with its specified attachment, addresses that without a key on the inside.