Spring latches are beveled-edge latches which are spring- operated
and automatically snap into position when the door is closed. This latch
offers security for situations where the threat and risk assessment
indicates threats from opportunists only.
Dead latches are identical to the standard spring latch except that
when the door is shut, the spring action is locked by a pin- operated
lever beside the bolt. The pin is depressed by part of the striker plate
when the door is shut. This latch offers security only when the threat and
risk assessment does not indicate a threat of door frame spreading.
Deadbolts are usually operated by a key or thumb turn and do not
incorporate a spring function. This type of bolt, properly fitted, will
withstand most amateur attempts at prying. A hardened steel deadbolt with
a 25.4 mm (1.0″) throw offers excellent security if it is installed
in a high quality door and frame in a strong wall assembly.
B. Lock Bodies
Bored, cylindrical or tubular locks are installed in a circular
hole in the door. They are easy to install, inexpensive and easy to use. A
bored lock may employ any type of latch or bolt and may be used on its own
or as an auxiliary lock. It is available in various models, for example:
key both sides, key one side or key outside with
thumb turn inside. The use of double cylinder functions on egress doors in
any public building is prohibited by the National Building Code of Canada
(1995), articles 3.4.- 7.12(14), A-188.8.131.52(14) and 184.108.40.206. Although use
of this type of lock function in a private residence is not regulated by
the code, the Fire Marshall\’s Office will not support the use of any lock
that could prevent the rapid departure of persons inside the building in
emergency situations. Check local regulations.
Rim locks are face-mounted door locks. The lock body is mounted on
the inside of the door and the strike is mounted on the inside of the
frame. Latches or pins may be used in the rim lock. These locks are easily
installed. However, the security afforded by a rim lock depends to a large
extent on the method of fixing the lock and strike to the door and frame.
Mortise locks are designed to be installed in a mortise rather than
being applied to a door\’s surface. They are usually used with solid-core
doors or hollow metal doors.
C. Glass Door Locks
Glass doors with narrow stile frames require a lock
with a pivoting
bolt that moves deeply into the frame or stile of the
Where extra protection against prying is desired in a
sliding door, a
hook bolt should be installed. Bolts should be made
of hardened material designed to resist sawing attacks.
D. Cylinders and Keys
The cylinder, which receives the key, is the heart of the lock. The
cylinder determines the size and shape of the key. A cylinder which screws
into the lock body should have either a sloping edge or a rotating safety
collar to resist removal with a vice wrench.
A standard cylinder can be replaced by a high security cylinder to
make the lock more resistant to picking, drilling and sawing attacks. A
further advantage of this type of cylinder is the relative difficulty of
acquiring duplicate keys.
Strikes are used to protect the lock bolt and to add
strength to the
total locking mechanism.
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