You have the keys. Congratulations — you also have no idea how many other copies of those keys exist, who has the garage code, or where the water shuts off if something goes wrong at 2 a.m. on night one.

That's the uncomfortable truth about closing day: you inherit a house, and you inherit its entire access history along with it. Past owners, their agent, the listing agent, a contractor who redid the kitchen in 2022, a dog walker, a neighbor who watered plants during a two-week vacation — any of them could plausibly still let themselves in. This isn't paranoia, it's just math. A house that's existed for any length of time has accumulated a small, untraceable population of people who've had a key or a code at some point.

This isn't the full home-maintenance calendar — we've got a separate guide on this site for the year-round schedule (gutters, HVAC filters, all of it). This is the shorter, sharper list: the handful of things that are genuinely urgent because they're about access and safety, not upkeep. Do the "today" section before you unpack a single box. Do the "this week" section before you get busy and forget.

Do today: locks, codes, and access

Rekey or replace every exterior lock

This is the single highest-priority item on this list, full stop. Every locksmith, security blogger, and real estate agent who writes about move-in day says the same thing, because it's true: you cannot know how many keys are floating around, so the only fix is to make the old keys stop working. Rekeying means a locksmith changes the internal pins so your existing lock hardware works with a brand-new key — cheaper and faster than swapping the whole lock, and the standard advice for anyone moving into a previously-owned home (Elmer's Lock & Safe; Late Night Locksmith).

Cost, as of 2026: rekeying typically runs $15–$35 per cylinder if you bring the lock to a shop or have someone come to you, with a locksmith's trip/service-call fee usually adding another $60–$140 on top. A typical 3-door rekey lands somewhere around $250–$350 all-in (Acme Locksmith). Full lock replacement — new hardware entirely — runs more, roughly $35–$150 per lock in parts and labor, and makes more sense if a lock is old, damaged, or you want to upgrade to something better anyway.

Skip it only if: the seller can hand you a documented, complete key history (rare, and honestly still not worth the risk for the cost involved), or you're planning to install smart locks anyway (see below), in which case the smart lock replacing the deadbolt handles this for you.

If you're comfortable with a screwdriver, you can also do this one yourself — most rekey kits for standard pin-tumbler locks cost well under $20 per lock and take about 10 minutes once you know the process, no locksmith required.

Reprogram the garage door opener

An open garage is one of the easiest ways into a house, and garage door openers are commonly overlooked in the "change the locks" conversation because nobody thinks of a garage door as a lock. Most modern openers have a "Learn" button on the motor unit (usually mounted on the garage ceiling) that, when held for several seconds, wipes every remote and keypad code that's ever been programmed to it — instantly invalidating any opener remotes, old keypad codes, or car-integrated buttons (HomeLink, etc.) that past owners or contractors were using (Heritage Door; Raynor). After the reset, reprogram your own remotes and set a new keypad code. This takes maybe 15 minutes and costs nothing.

Reset every smart lock and security system account

If the house has smart locks (August, Schlage, Kwikset, Yale) or a monitored security system (ADT, Vivint, SimpliSafe, Ring), treat these the same as physical keys — except worse, because a forgotten smart-lock account can let someone unlock your door remotely from their phone without ever showing up in person.

  • Smart locks: factory-reset the lock and re-pair it under a new account. Most manufacturers have a documented reset procedure for a lock you didn't originally set up — August publishes one specifically for buyers of a previously-owned home, and it's a good bet other major brands do too. If you can't verify the reset procedure for your specific model before move-in, flag it:.
  • Security systems: call the monitoring company directly (not the previous owner) to transfer or open a new account and get a fresh PIN — most companies won't hand over the old PIN to a non-account-holder for exactly this reason. If the equipment stays but you don't activate monitoring, the local alarm can still function and sirens can still sound, but you lose remote arm/disarm and any camera access tied to the old account (SecureLiving on inheriting an ADT system). Either way, don't assume a dead app login means the system is actually disconnected from the last owner — confirm it.

Budget an hour of phone calls for this one, and don't put it off — it's the item most likely to get "I'll do it next week" and then genuinely forgotten.

Do today: know where the emergency shutoffs are

You don't need to touch these yet. You need to know where they are before a pipe bursts or a breaker trips at 11 p.m. and you're on your phone flashlight trying to find them for the first time.

  • Main water shutoff valve — usually where the main line enters the house: a basement, crawl space, utility closet, or exterior wall. It'll be a lever handle (turn a quarter turn to shut off) or a wheel handle (turn several full rotations). Locate it and physically test that it turns — valves that sit untouched for years sometimes seize up, and you want to find that out on a calm afternoon, not during a flood.
  • Electrical panel/breaker box — find it, and check whether the breakers are labeled (they often aren't, or are labeled wrong by a previous owner who rewired something). If they're not labeled, walking through and labeling them yourself is a good rainy-day project, but the urgent part is just knowing where the box is and which breaker is the main shutoff for the whole panel.
  • Gas shutoff (if you have gas service) — locate the meter, usually on an exterior wall. The standard advice here is awareness, not DIY: know where it is so you or first responders can get to it fast, but don't practice shutting it off yourself — that's a call-the-gas-company situation (DIY Playbook's emergency shutoff guide).

This costs you fifteen minutes and literally nothing else. Do it before you're distracted by furniture delivery and forget the house has a basement.

This week: safety devices and less-urgent-but-still-important items

Test every smoke and CO detector, replace the batteries regardless

Test every unit in the house on day one — don't assume the ones that are there are working just because they're mounted on the ceiling. Then replace the batteries anyway, even if they test fine; you have no idea how old they are or how the previous owner treated battery swaps. Beyond batteries, check the manufacture date printed on the back of each unit: the National Fire Protection Association recommends replacing smoke detectors entirely every 10 years, and combo smoke/CO units on a shorter 5–7 year cycle since the CO sensor degrades faster than the smoke sensor. If you find a detector nearing or past that age, replace the whole unit — a $10–$50 part, per Angi — not just the battery inside it.

Check and set the water heater temperature

Water heaters commonly get left at factory-default settings that run hotter than they need to. The Consumer Product Safety Commission recommends 120°F as the setting that balances safety against usefulness — at 130°F, a scald burn can happen in about 30 seconds of contact; at 140°F, in about 6 seconds; at 150°F, in about 2 seconds. Even at 120°F, prolonged exposure (the CPSC cites around 5 minutes) can still cause a burn, so this isn't a "set it and never think again" fix, especially with kids or elderly family in the house — but knowing the previous owner's setting and dialing it back to something sane is a five-minute job with real safety upside.

Locate the sewer cleanout

The cleanout is the access point a plumber uses to clear a clogged main line without having to cut into a wall or dig up your yard blind. It's typically a 4-inch pipe with a screw cap and a square knob on top, usually poking up out of the ground somewhere between your foundation and the street, or occasionally near an exterior wall close to a bathroom. You don't need to do anything with it now — just find it and remember roughly where it is, so if you ever get a backed-up drain, you (or the plumber you call) aren't starting from zero.

The one-page version

Today, before you unpack: - Rekey or replace every exterior door lock - Reset the garage door opener (Learn button) and reprogram your own remotes/keypad code - Reset smart locks to a new account; call the security monitoring company to transfer or reset your account and PIN - Find and test the main water shutoff - Find the electrical panel and note whether breakers are labeled - Find the gas meter/shutoff (know it, don't touch it)

This week: - Test every smoke/CO detector, replace all batteries, and replace any unit past its 10-year (or 5–7 year for combo CO units) mark - Check the water heater temperature and set it to around 120°F - Locate the sewer cleanout

Everything else — gutters, HVAC filters, caulking, the twelve-month maintenance rhythm — belongs on the longer calendar, not this list. This one's just about not getting burned (sometimes literally) in the first week because you didn't know who else had a key.

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