Window Security – Casement Windows
Window Security – Casement Windows
A casement window has a fixed frame and one or more side or top-hinged opening frames (casements). Each casement should be fitted with at least one key operated casement window lock. This should be positioned just above or below a centrally mounted window catch. A small fanlight (top-hinged) window should also be locked.
On a window that is greater than 1m (3 ft 3 in) in width or height, or for increased security (particularly on a rear or side ground-floor window), fit a pair of locks, one opposite each hinge. Use two locks on the fanlight if the window is in a vulnerable position.
Steel and aluminium windows can be fitted with purpose made, surface mounted metal window locks in the same numbers and positions. When fitting locks to double-glazed windows, take care not to break the glass with the drill bit or self-tapping. Metal windows (particularly steel types) can also be fitted with cockspur handle locks. This type fits just below the cockspur handle to prevent it from being opened.
Plastic windows without multi-point locking mechanisms are a little more challenging to secure. For a retrofit lock to have any real strength, it must be secured through the plastic and into the inner steel framework. Before attempting to fit locks to plastic windows, contact their supplier or manufacturer for advice and to find out if your proposed security improvement would affect any warranty that came with them. If you are not confident about fitting locks to plastic windows, employ a locksmith.
There are three basic types of window lock for ordinary casement windows: automatic, press-button and swing locks. Sometimes, they are called ‘frame-to-frame’ locks because each comprises two parts, one being attached to the opening frame and the other to the fixed frame.
The easiest type of window lock to use is the style that locks automatically when you close the window; you only need a key when you want to unlock it. With an automatic lock, if you’re in a rush to go out, all you have to do is close the window to be certain that it’s secure.
This is another easy lock, only requiring you to press in a button to engage it. To unlock the window, you need a key, but only if you’ve pressed the button.
This type of lock has a hinged bar on the casement that swings over a tab attached to the fixed frame; normally, it is tightened in place with a key. Although time consuming to use, a swing lock does pull the casement tightly into the frame, offering the benefit of improved draughtproofing! Unfortunately, this type of lock is not suitable if you suffer from arthritis or some other disability that makes using your hands difficult. In this situation, you would be better off with an automatic or push-button lock, which normally requires only a quarter-turn of the key to unlock.
Flush fitting casement windows
Some large, older houses have very big casement windows. In these, the opening frames may be flush with the fixed frames, rather than being set back into them, which is the normal arrangement. This makes it difficult to use some swing locks and automatic locks. Fortunately, these windows can be fitted with window mortice security bolts, which are installed into the leading edge of the opening frame at right angles to the grain of the wood. Two are required for really big windows.
Window Mortice Security Bolt
This is a smaller version of the door mortice security bolt, which is often called a window mortise rack bolt. These locks provide a good level of security for very large, flush casements. They are normally fitted in pairs, one at the top and one at the bottom of the window, opposite the hinges. Each unit comprises a bolt within a cylindrical case, which fits tightly into a hole (mortice) drilled at right angles to the grain of the wood. Normally, it is fitted into the opening frame, and the bolt shoots into the fixed frame.
However, there is no reason why it can’t be installed the other way around, especially if the fixed frame is of a larger section than the opening casement. They can operate either vertically or horizontally. Mortise security bolts use a common splined key, which could easily be carried by a burglar. However, these bolts can only be operated from the inside (there’s no keyhole on the outside) and unless a burglar broke through the glass to reach the lock, he would not be able to take advantage of having a key. If you are concerned about this possibility, you can buy a key cylinder that fits into and covers the splined keyhole.
As an alternative to the mortice security bolt, you can fit a flush pivot, or semaphore, lock. As a rule, this is fitted to the opening frame and secures the window with a hardened steel bolt that drops over the fixed frame with a movement that resembles an old-fashioned railway signal. Some of these locks employ a keep, attached to the fixed frame, for a little extra security. The bolt is engaged either by turning a catch or using a key.