Unless you've bought a brand new house and are its first inhabitants, any home you buy will have a human history. A whole family life has been played out under this roof, although it's now your family's turn to make some memories here. But what about those former residents? Changing the locks to a home after you've bought it—is this a sensible thing to do, or is it much ado about nothing?
Those Spare Keys
The likelihood of a spare key (or keys) still in circulation certainly exists, but the risk that it will ever be used to enter your home is going to be minimal. Just think, is it really likely that a previous occupant of the property (or someone in possession of a spare key) will enter your home to burgle you?
History of the Property
The possible number of spare keys still out there has the potential to be unsettling, and if anything, changing the lock on your front door can be good for your peace of mind. This is especially true when you know that there have been multiple inhabitants over the home's history, such as if it had been used as a rental property prior to you purchasing it.
Changing or Altering the Locks
By all means, call a mobile locksmith if you're at all uncertain. They will give you a couple of options to render all keys for the front door absolutely useless in a matter of moments. The locksmith can change the lock and issue you with new keys. Another option is that the lock is rekeyed, in which the cylinder is removed and the pins are altered (the pins within the lock tumbler correspond to the notches on the key, which is how the lock recognises the key). Any old keys will no longer work, and the locksmith can issue you with a new key (and spares) on the spot.
Other Points of Entry
In terms of changing or altering the locks of your new home, the front door should be your primary concern. Windows might be unlocked, or their locks might be completely internal (with no exterior-facing keyhole). Any other door locks could also be secured (replaced or rekeyed) unless it's a sliding door. Additional locks for sliding doors are generally internal, with the deadbolt extending into a strike plate on the floor of the room. If this additional lock has not been added, a piece of wooden dowel placed into the sliding door's tracks can render the door immobile when you're out.
Sometimes changing the lock on a new home will do wonders for your peace of mind, so remember that a locksmith can very quickly rekey an existing lock.