The lock is rarely what breaks
A common mistake is to spend heavily on a lock and ignore what it is attached to. When a door is kicked or shouldered, the force goes into the whole assembly: the door slab, the hinges, the lock bolt, the strike plate and the frame. The weakest part gives way first, and that is often the wood around the strike plate rather than the lock.
A typical door frame consists of a vertical jamb (the side piece), a head jamb across the top and a decorative trim, or casing, on the outside. The jamb is usually fairly thin softwood. The bolt on the lock extends into a small hole cut in that jamb. Under heavy force, the wood can split along the grain, the bolt slips out and the door swings open with the lock still locked.
None of this assures that any particular door will resist force, since results depend on the door, the frame, the wall and how it all was installed. But the logic is clear enough to guide choices.
What a strike plate does
The strike plate is the metal plate screwed into the jamb. It covers the cut-out where the bolt enters and spreads load across a larger area of wood. Standard plates that come with locks are often small, thin and held by two short screws, roughly three-quarters of an inch long, that grip only the jamb. Those screws bite into the thin jamb material and not into the solid framing behind it.
That is the weak point. Replacing the screws is one of the cheapest upgrades available.
Easy and inexpensive improvements
- Use longer screws. Replace the short screws in the strike plate with ones long enough to pass through the jamb and shim space and bite into the wall stud behind it. Three-inch screws are a common suggestion, but check the space behind your jamb and avoid screws that are too long to seat or that could hit wiring or pipes. If you are unsure what is in your wall, ask a professional.
- Replace the strike plate with a heavy-duty one. Longer plates of thicker metal reach further along the jamb and have more screw holes. Some wrap around the edge of the frame.
- Reinforce the hinge side too. Swap one or two of the short hinge screws with longer ones going into the stud. This helps if force is applied against the hinge side.
- Check the deadbolt strike separately. Deadbolts and latches usually have separate strike plates. Both should be secure.
These changes take minutes and need only a drill or screwdriver. Be careful, though: always check that the door still closes and latches properly after changing hardware.
Reinforcing the frame
For more resistance, various products exist to strengthen the jamb itself.
- Metal or steel door jamb reinforcement kits. These are long plates or channels that cover the lock-side jamb and attach to the stud, spreading the load along a longer stretch of frame.
- Wraparound door reinforcement. Some products wrap around the lock area of the door edge and help keep the slab from splitting where the lock is mounted.
- Replacing a cracked or rotted frame. If the jamb is already damaged, reinforcement will not help much. A carpenter can repair or replace the frame, which is an investment worth considering for a front door.
- Solid shims behind the jamb. A frame that is loosely installed with gaps behind it has less backing. A carpenter can check this.
Some jobs involve cutting into trim or wall material, so decide whether you are comfortable doing them yourself.
The rest of the door
- The slab. Solid wood, steel or fiberglass doors are generally more resistant than hollow-core doors. Hollow-core doors are usually meant for interior rooms.
- Hinges. Exterior doors normally have three. Check screw length, as discussed above, and make sure the door does not rely on exposed hinge pins on the outside. On outward-opening doors, security hinges or non-removable pins stop the door being lifted off.
- Door edge. Where the lock holes are drilled, the door is weakened. Some people add a reinforcement plate here, as mentioned above.
- Glass nearby. If a window or sidelight is within reach of the lock, the lock may be defeated without any force on the frame. Security film for glass or a different layout can help.
- Gaps. A big gap between door and frame gives a tool room to work. Weatherstripping and adjusting hinges to tighten the fit are worthwhile.
Inspect your own doors
Walk around the house and check each exterior door:
- Look at how far the bolt extends into the frame when locked.
- Check the screws on the strike plate and hinges.
- Press on the door near the latch and see if there is movement or flex in the jamb.
- Look for cracks, rot or old forced-entry damage.
- Note whether the door is solid or hollow.
If a door has been damaged or forced in the past, it is worth repairing the frame fully rather than just replacing the lock.
Where this fits
Frame strength works with locks, not instead of them. A well-graded deadbolt only performs well if the bolt is held by a solid frame. Add door contact sensors from a home alarm system if you want warnings, and consider the garage connecting door in the same way. It matters just as much for the interior door between an attached garage and the house.
If you rent, ask permission before changing the strike plate or frame. If you live in a fire-rated building, ask the building manager before changing hardware on a fire door.