Construction key

A construction key is a temporary key used by the tradespeople while a home is being built or renovated. In cylinders designed for it, it stops working as soon as the owner inserts and turns their own key for the first time.

That way the owner receives the house knowing that the keys that went round during the works are no longer any use. It usually comes in a different colour or with a different marking.

When you take possession of a new build home, ask whether the cylinder has this system and use your own key as soon as possible. If it does not have it, or you do not know how many keys have passed through other hands, the most prudent thing is to change the lock cylinder when you move in.