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I have a house that was built in 1975, and I plan to add another lock, a deadbolt lock, to my front door. Since the door has glasses on them, I wanted to know if it is structurally sound to add another lock. To be more specific, this is for safety purpose; to make it difficult for intruder to get in.

If adding a lock would decrease the structural strength of my front door, what other kind of lock or system can I add?

Any guidance would help. Image of the door below.

enter image description here

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  • would not advise
    – asinine
    Nov 8, 2022 at 8:24
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    A cheap hammer will open any lock on that door.
    – crip659
    Nov 8, 2022 at 9:44
  • Is the purpose to keep the door from intrusion when you're away, or when you're there? Two rather different scenarios, thus answers, I suspect.
    – Tim
    Nov 8, 2022 at 11:06
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    Any door that is decently made will take other locks without making them too weak. The glass windows in that door is probably the weakest point for security, break the glass and can open the locks. Probably faster than picking the locks.
    – crip659
    Nov 8, 2022 at 13:33
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    if you have other doors, use a double-key deadbolt so that breaking the window won't let you unlock it. keep the key in the door when home for fire safety. you can add a bottom slider lock (like a deadbolt for the floor) for when you're home to butress it against kicks. i would also hotlglue a thin sheet of lexan to the pane next to the deadbolt to that i can't be shattered and reached-through, without making a lot more noise than bare glass.
    – dandavis
    Nov 9, 2022 at 22:08

2 Answers 2

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If you did add a second lock, it would be best in-line with the horizontal strake between the top and middle pane of glass. A third lock could go down under the handle, again in-line with the wood.

Adding more locks will do little for real security - There is no good spot for another lock. Additional locks on that door will be a visual deterrent at best, and a time-sink for you every time you use it.

You might get more mileage out of replacing the existing latchset with something modern, before adding a second lock.


If I wanted to enter via this locked door, I'd try:

  • the handle first in case it is open, then a quick shove with a credit card at the lock's tongue, and a jiggle with a lock rake.
  • break the glass nearest the lock and manipulate it from the inside - probably opens without a key from behind.
  • sledgehammer the handle off and directly manipulate the square shaft inside with pliers.

One action is to replace the six single panes of beerglass with something more durable.

  • Wood - will make the inside foyer darker during the day. Very hard to break. Glued, screwed/nailed and painted this will add rigidity to your door. Weight goes up too, making it feel more solid.
  • Double-glazed inserts - still allows light, retains heat better, and is harder to break than single glass. Can be mirrored on the inside to add privacy.

You'd also want to replace that existing combo latch with a separate key-based deadbolt (it needs a key to open from the inside, and you take that with you when the house is empty)


Your existing door would not resist a brute force attack for long even if the lock was not targetted - a sledge hammer or sawzall would bust out the little horizontal pieces quickly, and if the middle vertical piece didn't fold up with the sledge, then the sawzall would take around 60 seconds to cut horizontally through it and then it folds down.


Ultimately your door is assembled from pieces - if you want it to be a lot stronger then replace the entire door panel with something solid, or at least with no holes in it.

Also consider uprating the door frame, and make sure the fastener screws you use are sufficiently long and that your new deadbolt goes home into the frame with minimal play.

Another option might be to add a second external door, like a screen door that uses strong mesh. This means opening two doors when you get home.


Afterwards go around your house and consider all the other entrances too. Garage doors tend to be weaker, where internal access gives a direct path into the house. Windows and sliding doors, cat/dog doors, celler/basements and attic/gable-ends can potentially be entry points.

Avoid overly-fortifying the Drawbridge and leaving your Postern gate unprotected.

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    I have decided to add a security mesh door. Thanks
    – sammy
    Nov 14, 2022 at 3:44
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That door is not very sturdy to begin with as it is.

If you want to add another lock,

use metal plate to strengthen the door frame.

Here are some samples

bolt

bolt 2

bolt 3

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