One door on the sidewalk. Several households behind it.

Whoever holds the building: the owner, or the management company acting for them. That is not a legal opinion and it is not our call to make between a household and an owner. It is arithmetic. One cylinder on that leaf means one decision that reaches every household on the stair, so a rekey ordered by one flat retires the keys of three neighbors who were not on the phone. Your own flat door is a different matter entirely and needs nobody's permission but yours. We ask which of the two you mean while the address is being written down, so that the van is not standing at a shared door waiting for someone to be reachable.

Being let back into the home you pay rent on is yours to arrange, and nobody phones the owner about a lockout. Bring photo ID with that address, or ID plus something on your phone that ties you to the unit, such as a lease page, a rent receipt or addressed mail. Changing what is screwed to your own flat door, a rekey or a proper deadbolt, is settled between you and whoever holds the building, and we ask for that yes before dispatch rather than after. Anything on the street door, the mail row or the yard gate goes through the owner or the manager the same way. A receipt can be made out to you, to the owner, or to both at once.

Eighteen minutes is the usual, worked from a base near Park Street. Park Street District runs about 12, Gold Coast 14, Fernside 16, Central Alameda 18, South Shore 20, West End 22, Alameda Point 25 and Bay Farm Island 27 across its own bridge. Off the island the same price list applies: Oakland about 16, Emeryville 21, Piedmont 23, Berkeley 25, San Leandro 26, San Lorenzo 29. Those numbers already allow for the crossing, which is why two addresses that look close together on a map do not come back with the same figure. Where yours is one of the long ones you hear the long one while you are still on the phone.

It changes the wait and nothing else. A lift bridge goes up for a boat on the schedule the port runs to, and there are three of them plus two tubes under the estuary, so the honest answer on the phone is which crossing the van has in front of it and what that adds. That is why the arrival time you get is drawn from where the vehicle actually is rather than from a number printed on a card. The only two things that move a figure here are the door in front of the technician and the hour on the clock.

The flat door, that week, at $30 to $47 per cylinder, plus anything else that opens only into that unit such as a back door, a storage cage or a shed. That much is straightforward. The street door is the conversation worth having early rather than in a hurry: it is shared, changing it means new keys for every household in the house, and it is the owner or the manager who decides and pays. Plenty of buildings here do it once every few turnovers rather than every time, and knowing which one you are in before the ad goes up is easier than deciding it on a Friday. The mail lock for that box is worth doing at the same visit, since the van is already at the curb.

The lock in a residential mail row is a cam with a small wafer pack behind it rather than a house cylinder, and replacing one is minutes of work once somebody is standing there. Two things make it slower than it sounds. It is building hardware, so the owner or the manager approves it, the same as the street door. And doing one box in a row of four often uncovers the real problem, which is that six or seven keys are in circulation for four boxes because tenancies have come and gone. Where that is the case the sensible job is the whole row at once, each box on its own key, with a written note of what was handed to whom. Boxes served by the postal service have their own arrangements, and you are told which of the two you have before anything is unscrewed.

Three things, and the brand of lock is not one of them. What the leaf is doing, since a tall old front door that has settled on its hinges is a different afternoon from a flat door hung twenty years ago. How many cylinders end up in the job, because one street door and three flat doors is one visit but four locks. And the hour, since an arrival after 8pm carries $50 and after midnight $88. Settle those three on the phone and the range closes to a single figure, which is the figure that reaches your card.

A Saturday costs what a Wednesday costs, and so does the Fourth of July. Only the clock changes anything: $50 added for an arrival between 8pm and midnight, $88 between midnight and 7am. Both go into the number before you agree to it, so nothing new turns up once the door is open. A house lockout at $160 in the afternoon is quoted as $210 at ten in the evening and $248 at two in the morning, and those are the figures on the receipt.

Walk the address and count the locks before buying anything, because there are almost always more than you think. The street door with its one cylinder. Each flat door. The mail row. The gate into the side yard, which the neighbors on one or both sides often use as well. A basement or laundry door. Then work out which of those you want on one key of your own and which have to stay separate, and rekey to that plan at $30 to $47 per cylinder in a single visit rather than piecemeal over a year. If any exterior door has to be lifted or shoved before it locks, point at that one too, since the repair there is usually a keeper and two long screws rather than a purchase.

All six, around the clock, on the price list Alameda gets. Distance buys you a longer wait and nothing else: Oakland about 16 minutes, Emeryville 21, Piedmont 23, Berkeley 25, San Leandro 26 and San Lorenzo 29, against 12 to 27 on the island itself. Divided houses do not stop at the water either, so the same question about who approves work on a shared entrance gets asked on the mainland exactly as it does here.