Door Locks and Home Security Hardware

Door Locks and Home Security Hardware

Rim Lock

Often called a night latch or ‘Yale’ lock, a rim lock comprises a lock body, key cylinder and keep or staple. It fits on the inner face of the door and is operated from the inside by a knob, and from the outside by a key. The bolt is spring loaded and is known as a ‘live’ bolt. It has a rounded shape so that you can shut the door without using the key or knob. Rim locks vary in quality and the price you pay will usually determine a lock’s effectiveness against a burglar.

All doors need a live bolt (or latch) so that you can easily open and close the door, and although this is usually provided by a rim lock, sometimes it will be incorporated into a multi-point locking system (as often found in a PAS24 door set) or a mortice lock (a sash lock). Most rim locks have a ‘lock-back’ snib or slider that enables you to secure the live bolt in the locked or unlocked position. There is no security value in this; it is intended only as a means of stopping the door from locking you out when you need to carry something through.

The more secure types of rim lock incorporate a spring loaded pin in addition to, or as part of, the live bolt, which automatically deadlocks the live bolt when the door is closed. This prevents the live bolt from being slipped back by forcing a piece of plastic between a loose fitting door and its frame. Other rim locks can be deadlocked with the key from the outside.

The better rim locks, especially those that carry the BS 3621 Kitemark for thief-resistant locks, have a locking knob as well, which you can lock using its own cylinder as you go out, or by a double turn of the outside cylinder. The knob is unlocked using the outside cylinder. Only use this facility when your home is unoccupied so that you don’t accidentally lock somebody inside. There are two reasons for locking the internal knob: to prevent a burglar from breaking the glass and using the knob to open the door, and to make the successful burglar leave your home by the same route that he entered.

When buying a new rim lock, make sure that it is British Standard Kitemarked. Such locks are designed to resist attack by drilling the cylinder, sawing the live bolt and otherwise forcing the mechanism. There will also be a minimum of a thousand key differs, but since they all use cylinders, the actual key differs will number many thousands. Make sure you buy a lock that is handed correctly (depending on whether the door is hinged on the right or left) and that its size matches the stile width of the door. The main weakness of the rim lock is the installation, especially that of the keep. Make sure that you use the longest screws possible to fit both lock and keep.

Mortice Deadlock

Door Locks and Home Security Hardware - mortice deadlock The mortice deadlock, which is normally used on front doors and private flat entrance doors, is fitted into a slot (mortice) cut into the leading edge of a door. Mortice deadlocks are available in two body sizes for standard-width and narrow door stiles. The deadbolt, which is operated by a key and a levered locking mechanism or a cylinder, engages into a keep set into the door frame. A door fitted with such a lock should have a minimum thickness of 44mm (1-3/4 in) and be in good condition. There is a wide range of mortice locks, and the cost is likely to determine quality. At the very least, you should use a BS 3621 Kitemarked mortice deadlock for the final exit door, and for any door to an outbuilding that contains items of value. A BS 3621mortice lock will also be supplied with a boxed keep, which is cut into the door frame, rather than being a simple plate with a hole in it.

Unfortunately, many European manufactured locks will not carry a BS 3621 Kitemark. This does not necessarily mean that they should be replaced, as some offer a level of security that either matches or exceeds the requirements of that standard. In this situation, the best thing to do is ask the advice of a locksmith before you go to the expense of replacing it. If you have to remove the lock to do this, make sure you leave somebody at home. Check also that your insurer is happy about you using the lock, even if the locksmith tells you it’s the best thing since sliced bread.

Security Tip

If you are upgrading your door locks, buy your cylinder locks from a locksmith. He or she will be able to fit all of them with cylinders that use the same key.

Essential Advice

If you are tempted to key lock your doors from the inside at night, leave the keys in the locks. If you are worried about a burglar breaking glass or putting something through the letter box to reach a key, you can always strengthen these weak spots.

Mortice Sash Lock

A mortice sash lock combines the actions of a rim lock and a mortice deadlock in one unit, incorporating a live bolt (or latch) that is operated by a handle on each side of the door. The same BS 3621 standard applies to these locks, which are normally fitted to back doors and internal garage access doors. This type of lock is normally fitted just below the centre of a door, so mortice security bolts will be needed at the top and bottom of the door to reduce the amount of leverage that can be applied against the lock.

Multi-Point Locking System

In recent years, many homes have had their doors and windows replaced by double-glazed plastic and aluminium units. Most of these will have multi-point locking.

As a rule, a multi-point locking system has at least one hook lock, which engages with a keep in the frame and will resist a lever attack on the door. There will be at least two compression bolts that pull the door tight against the draught seals and contribute to the security of the door, and there will be a live bolt close to the operating handle so that you can open and close the door easily. Some systems also have additional bolts that shoot into the top and bottom frames, and the most secure versions have bolts that engage into the frame on the hinge side of the door.

In most cases, the hook locks, compression bolts and shoot bolts are engaged by lifting the handle. Then the key has to be turned in the cylinder lock to deadlock the bolts in place. This can be done from inside or outside of door. More recent types automatically engage some or all of the elements of the multi-point locking system when the door is closed.

A multi-point locking system will vary depending on the location of the door and its precise purpose. For example, the outside handle of a front door fitted to a typical two-storey house normally would only be used to engage the various security bolts, but wouldn’t operate the live bolt. This means that you would need the key to get back into the house each time you closed the front door, just like a door fitted with a rim lock. Of course, you could easily lock yourself out in these circumstances, which is a good reason to leave a spare key with a trusted neighbour or friend. Private entrance doors to flats above the ground floor, which open off an internal corridor (where there are seldom any windows to break should you lock yourself out), will have an outside handle that operates the live bolt as well as the other security bolts.

Mortice Security Bolt

Sometimes called a mortice rack bolt, the mortice security bolt provides additional security for doors that have been fitted with a mortice sash lock. It is more secure than an ordinary surface mounted barrel bolt, because it is key operated and fits into a mortice. This type of fitting should be installed in pairs, at the top and bottom of wooden back or side doors, French doors and internal garage access doors.

The unit comprises a bolt within a cylindrical case that fits tightly into a hole (mortice) drilled into the edge of the door frame across the grain. Thus, the bolt operates horizontally in single doors and vertically on double doors, shooting into a hole in the top or side of the door frame, or in the sill beneath the door. Mortice security bolts use a common splined key, which could easily be carried by a burglar. However, these bolts are only operated from the inside (there’s no keyhole on the outside), and unless a burglar broke through a door panel or glazing to reach the lock, he would not be able to take advantage of having a key.

For fire safety, these bolts should not be set at night. They should only be used to reinforce the security of your doors when you leave your home unoccupied. For extra security at night, employ simple barrel bolts.

Barrel Bolt

This surface mounted bolt is normally fitted to the inside of front and back doors, and is handy for providing a little extra night-time security when you’re tucked up in bed. Using a large barrel bolt, together with a BS 3621 mortice sash lock or deadlock and rim lock, will provide you with a good level of security without compromising your ability to escape through the door in an emergency.

Since a barrel bolt is surface mounted, it must be attached using the longest and thickest screws that are practical for the door and fitting. This may mean rejecting the screws supplied with the bolt.

Hinge Bolt

Also known as a dog bolt, the hinge bolt is a fixed steel bolt that is fitted in pairs to the hinge side of a wooden door. When the door is closed, the bolts engage into holes drilled in the frame. They serve two purposes. One is to prevent the door from being forced open on the hinge side – a rare event, but it does happen; the other is to prevent an outward opening door, which has exposed hinges, from being removed completely from the door frame by removing or cutting out the hinge pins. Hinge bolts should be fitted to all external wooden doors. The more expensive types have a boxed keep to receive the bolt rather than a simple steel plate with a hole in it.

It is normal practice to fit one hinge bolt about 150 mm below the top hinge and the second hinge the same distance above the bottom hinge.

Mortice Lock Reinforcing Plates

Cutting a lock mortice in a door frame inevitably weakens the wood. A tight fitting mortice lock will restore some of the lost strength, but if it is slightly loose, the lock could act as an internal lever and split the wood if force is applied. Mortice lock reinforcing plates, which are bolted through the door above and below the lock, sandwich the wood and lock tightly together to help prevent this from occurring during an attack. They should be fitted as a matter of course with all mortice sash locks and deadlocks.

Frame Reinforcement Bars

To increase the resistance of a door frame against splitting during an attempted burglary, you can fit flat steel bars to the inner faces of the frame. These can be obtained from locksmiths and are usually painted white. The locking-side bar, often referred to as a London bar, will have to be made to measure to fit around the rim lock’s striking box and any surface mounted barrel bolts that may be installed. The hinge-side bar, often referred to as a Birmingham bar, can be bought off the shelf and simply cut to length.

Security Tip

Over recent years, locking hinges have been developed. These incorporate a pin on one side of the hinge that locks into the other side when the hinge is closed. In effect, this does exactly the same thing as a hinge bolt – even if the hinge pin is knocked out, the door remains held in the frame.

18. December 2010 by admin
Categories: Home Security | Tags: , , , | Comments Off on Door Locks and Home Security Hardware


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