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We’ve written all about front door security for individual flats or homes, but what applies there doesn’t necessarily apply to a communal entrance door on a block of flats. The needs of the two doors are quite different.

A flat door only needs to let in those who have a key. A communal door needs to let in all kinds of people, including tradesmen, postmen and other people who don’t have a key (e.g. visitors who are being buzzed in by one of the tenants).

You want to keep your flat front door nice and secure, so that only people can come in who have a key or who are let in by you. A communal door needs to let everyone in and out all the time.

The fire safety implications are also quite different. Your front door needs to be fire safe, yes, but it’s not the end of the world if you have a deadlock on the door that can only be opened with a key. Nine times out of ten, you’ll be able to access your key in an emergency, and you’ll know where it is.

On a communal door it’s quite different. First of all, the door is the bottleneck for everybody. If 100 people live in the building, all 100 have to exit via the communal door. It therefore has to be easy to use, it can’t involve any fumbling around for keys, and it needs to be intuitive for any guests in the building who are unfamiliar with the door. That’s why a good communal entrance door has just one lock on it which can be opened from the inside without a key.

(Some buildings, e.g. offices, get fully locked up at night. In this case, you could install a deadlock underneath a latch lock, which gets unlocked in the morning. Even this, though, needs a thumbturn on the inside so that, in case anybody does get locked in, they can escape freely.)

This all makes it sound like a communal entrance door must be by its very nature insecure. This needn’t be the case, however.

All manner of strong locks exist which allow communal doors to be secure. Furthermore, it’s normally possible to fit a London bar, letterbox cowl, auto-deadlocking nightlatch and high-security cylinder to the door.

Anti-thrust plates

There’s one thing that communal doors are vulnerable to, to which homes often aren’t vulnerable: credit card attacks. While a standard Yale lock can be ‘slipped’ open with a card, the deadlock (which most house front doors have) spares the door from this kind of attack.

Given that communal entrance doors don’t usually have deadlocks on them, it’s often possible to slip them open. As a result, some doors have so-called anti-thrust plates fitted to them. These are essentially just strips/plates of metal that block access to the gap between door and frame, where you would ordinarily put a credit card. Sometimes these anti-thrust plates are quite short but, depending on the risk factor, you might find the occasional full-length plate.

“Why can’t you just put an auto-deadlocking nightlatch onto the door?” I hear you ask. Not all doors are suited to Yale-style locks, and not all latch locks are auto-deadlocking.

Electric release

Ever wondered how somebody can just ‘buzz you in’ when you’re standing outside a communal door? This is usually done with an electric release. Instead of having a standard ‘keep’ in the frame (the keep is the piece of metal into which the bolt of the lock goes), you have an electrically powered one that can move out of the way when requested. This means that the door can then swing open.

Electric releases come in flimsy varieties and in chunky, secure ones. The chunky ones are hard-wearing and you’d struggle to force them open. But even a flimsier one can be reinforced using the aforementioned London bar.

As with the Yale locks mentioned in the previous section, not every door is suited to the same locks. Some high-risk doors simply can’t take the fat, robust electric releases.

Sometimes it’s the lock itself that is electric, rather than the keep. In other words, when somebody buzzes you in, it’s the lock that gets powered up, not the bit in the frame. At Metrolocks, we like to use the CISA electric lock, a very robust and secure lock. When you buzz someone in, the locking bolt retracts automatically so that you can just push the door open. It also makes a very clear buzzing sound.

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