Add a Door Reinforcement Lock

Before you start

• Confirm the door swings inward. Every flip latch here is listed for inward-swinging doors only, and there is no way to make one work on an outward-swinging door.
• Find out whether the door is fire-rated. Drilling into a fire-rated door or frame can void the rating it was certified with, and in shared buildings the entrance door very often is rated.
• If you rent, ask the landlord in writing before drilling. Screws into a door and frame are an alteration, and this is the most common way people lose a deposit over security hardware.
• Work out who could be alone behind this door, and whether anybody outside would be able to reach them if they could not release it themselves.

The job

1. Decide the height before you decide anything elseThe point of this device is distance from the deadbolt, so it goes high — normally near the top of the door, above the lock line. It also has to be a height every adult in the household can reach and operate one-handed. If those two requirements fight each other, the second one wins.
2. Check what is behind the frame at that heightThe bracket has to bite into something solid. Tap along the jamb and find where the framing sits behind the trim, because a fixing into a thin jamb board alone is carrying very little. If there is a gap between the jamb and the framing, a packing shim in that gap is what stops the frame flexing when the screws are tightened.
3. Mark, then close the door and mark againHold the plate against the door and mark the holes, then hold the bracket against the frame with the door closed so the two parts line up in the position they will actually meet in. Doors are rarely square to their frames. Marking both halves with the door open is how you end up with a latch that will not drop.
4. Drill pilot holes, undersizedPilot holes stop the screws splitting the jamb, which is the failure that turns a security fitting into a repair job. Use a bit narrower than the screw core, not the screw thread. On a hollow-core door, stop and read the stop signs below before going further.
5. Fit the frame bracket first, then the door plateGet the fixed half solid and square before you hang anything off the moving half. Drive the screws until they are firm and then stop; overdriving strips the hole and a stripped hole holds nothing. If a screw spins without tightening, back it out and move to a fresh position rather than forcing it.
6. Test it twenty times, from both sides of being tiredEngage and release it repeatedly, then get everybody in the household to do the same. It should drop into place without lifting the door and release with one hand without looking. A device that needs a knack is a device that fails at the moment it matters.
7. Write the release into the household routineAgree out loud when it is engaged and when it is not: on while people are in and awake, off before bed and before leaving. Tell overnight guests. This step is not optional padding — it is the difference between a useful layer and a trap.

Stop and call somebody if

• The door is hollow-core. There is nothing inside it to hold a load-bearing fixing, and a reinforcement lock on a hollow door tears out with the panel around it.
• The door or frame is fire-rated, or you cannot establish that it is not. Ask the building manager before any screw goes in.
• The jamb is soft, split, or moves when you press it. Fix the frame first; a fitting is only as good as what it is screwed to.
• Anybody in the household would struggle to reach or release it. That is a hard stop, not a design constraint to work around.

What goes wrong

• Fitting it at a comfortable height for the tallest person in the house, which puts it out of reach for everybody else.
• Leaving it engaged as a permanent state, so a door that nobody outside can open becomes the normal condition of the home.
• Treating the load figure on the box as a specification. It is the seller’s claim about their own test, and it says nothing about the softwood your screws went into.

Where this applies

• The Front Door — The jamb, not the lock: on most homes the strike plate is held by screws that stop inside a thin board nailed to the framing behind it.
• A Rented Apartment Door — The key list: in a rented apartment you have no idea how many keys were cut before you arrived, and no lock upgrade you can make changes that.
• The Back Door — Privacy: a back door is usually the only approach to the house where somebody can work unobserved for as long as they like.

Hardware this job may need

• Door Reinforcement Locks & Bars — buying time at the door, without blocking the way out

Sources

• National Fire Protection Association — home fire safety and escape planning
• U.S. Fire Administration — home fire prevention and preparedness
• U.S. Department of Housing and Urban Development — renting resources