Window Locks
Types of window lock
Wooden casement
Fit window locks which secure the frames together in preference to window locks
which simply secure the handle or stay bar. Casement windows, by
their very design, need to be locked by securing the window to the
frame. Most casement window locks are screwed to the window rather than
the frame - a weaker system. There are window locks which are fixed to
the frame and these are probably more secure, as well as being easy
to use.
There are also window locks specifically designed for use on windows with tapered edges (not 90º to the frame).
If the window is flush to the frame fit mortice rack bolts (bolts
fitted into the window and operated internally with a key). They
should always be fitted at 90º to the grain of the wood, reducing
the likelihood of the wood splitting if subjected to pressure and
fixed into either end of the frame. You might want to consider using
door mortice bolts for a longer throw.
If you are intending to use the type of Window lock that screws to the
window, the following test is a rough guide to help you to decide
how many you will require: with the window closed, press each opening
corner. If there is any movement, fit a suitable window lock,
such as a push lock (push to lock, key to open) at each corner on
the opening side. If there is no movement, a window lock fitted to the
centre of the opening frame will suffice.
It is possible to secure wooden casements in the open position for purposes of ventilation, very necessary in hot weather, or child safety. These are particularly appropriate in a ground floor bedroom situation where someone wishes to sleep with the window open.
Likewise they are well suited to upper floors where windows can be locked open, allowing ventilation but, at the same time, preventing children from opening the window beyond a safe aperture. Whilst it is recognised that this type of device is designed more for safety purposes rather than security, it would be likely to alert the occupant if an attempt to force it was made. It is intended that these locks should be used only when someone is in residence. If your home is unoccupied the windows should be locked in the usual manner.
If you are considering replacing your existing windows, look for the new British Standard 7950 kite mark. It has been established to set specific manufacturing standards of design and security for casement windows.
Note: Georgian wired glass may look strong, but it will easily break. It is a fire safety glass not a security glass.
Wooden sliding sash
You
cannot rely on existing central sash fasteners. Sash
stops are strong and convenient to use and do not need to be removed
from window when opening fully. They can be set into the top frame
allowing the window to be left open about 5" for ventilation
but still secure. For optimum security fit window locks in pairs.
An
alternative form of lock is the dual screw. These in effect bolt
the two sashes together. An added bonus is that, in so doing, they
also reduce draughts.
The beading which holds the glass in place is frequently only pinned. The window can be made more secure, either by gluing in addition to pinning or screwing the beading, if wide enough, in place.
A modern style is the 'tilt to clean' sliding Sash window, not only sliding up and down but also tilting inwards for cleaning by undoing two clips on top of each moving sash. These should be secured by fitting both sash stops and dual screws.
Metal Crittal
You
can either secure the window or the handle to prevent opening. One
of the main problems with this type of window is the narrow profile
of the frame, making it difficult to fit devices.
For this reason there are locks specifically designed for this type of window. It is probably easier to secure the handle, where there is normally more room to fit the window lock. Use a fanlight lock to secure the fanlight window.
Aluminium
The highest level of security fitted by the manufacturer on most aluminium windows, including coated aluminium, is a locking handle, but, whilst it would be satisfactory to most insurance standards, it is not particularly secure. This is because it is the handle which is being locked and not the window. As most handles are not of a good casting standard they have a tendency to break under pressure, or come loose from the frame.
It is possible to fit extra window locks to aluminium windows, but care should be taken to ensure that there is enough metal around the window to be able to fit the window lock without contacting the glass. Suitable locks designed for this purpose are available.
In the case of sliding horizontal aluminium windows, additional security can be achieved with the fitting of a key operated clamp on the bottom rail of the frame. Windows are often left open to allow the circulation of air, particularly in hot conditions. This, inevitably, reduces the level of security. By fitting a sliding window lock to the bottom rail you can restrict the slide to a few inches.
Alternatively, drilling a small hole through the bottom rail at the point at which you wish to restrict the slider and inserting an appropriate sized bolt will suffice. Additionally, to prevent the slider being lifted, fit a wooden block of a suitable depth into the track above the slider.
Louvres
Louvered
windows are not so common as they used to be. In the main, this
is because their inherent lack of security is well recognised. There
are some measures that can be taken to make them less vulnerable,
but these should be seen only as temporary, for overall, it is best
to replace them at the earliest opportunity.
Some are made with the glass secured in the frame. If not, fix the glass in both frames with an epoxy resin adhesive. If the windows are sited in a vulnerable position, you may need to fit a grille or bars, though the better option would be complete replacement.
UPVC / PVCU
In
many cases it is not possible to retro-fit any extra locks to UPVC
windows. This is because the material used is not strong enough
to support a metal window lock fitted with steel screws. It could also
damage the window and perhaps invalidate any existing warranty.
Double glazed window locking systems should be fitted at the time of manufacture. A general rule to follow is that the handle should not be the only means of keeping the window closed. The locking system should be fitted within the framework and the handle is used as a means of throwing or engaging the internal locking system.
Always consult the manufacturer/supplier before attempting to fit any extra locks. There are locks that can be fitted to UPVC casement windows, but only if there is no integral locking system within the framework, typically where the only means of security is a locking handle.
There are two main types of locking systems:
- The first is espagnolette (multi-point) locking, which are bolts (normally 3 sets) set into the window and located into locking points in the frame when the handle is turned. The bolts should be mushroom headed so that they can engage behind the locking point, thus enabling the window to resist being forced apart from the frame.
- The second type is deadlock shoot bolts which locate into the frame at both opening side corners. There is also a deadlock which secures the opening side of the window at the handle. The window can also be fitted with high security friction hinges which locate into the frame on the hinge side.
For additional strength sections of hardened aluminium or galvanised steel reinforcements should be fitted at the time of manufacture within the hollow profiles of the windows and frames, so that the locking systems can be secured through the UPVC frames into the reinforcements.
It is preferable for the windows to be fitted with internal beading to avoid the possibility of the glass being removed from the outside. There are some systems which have external beading but are secure because the glass is adhered to the frame or secured by special tamper-proof clips, but in most cases internal beading is preferable.
Lastly, if you are considering replacing your existing windows, look for the new British Standard 7950 kite mark. It has been established to set specific manufacturing standards of design and security for windows.
Secondary glazing
Though they are not installed these days, there are still many houses fitted with secondary glazing, mainly aluminium. Because of the narrow profile and intrinsic weakness of the frames, there is very little additional security which can be added. Such glazing has generally been fitted to wooden framed windows, which can be secured by standard window locks.
However, sliding secondary glazing can offer additional security with the fitting of a key operated clamp on the bottom rail of the frame. Particularly in hot conditions windows are left open to allow the circulation of air. This, inevitably, reduces the level of security. By fitting a sliding window lock to the bottom rail you can restrict the slide to a few inches.
Alternatively, drilling a small hole through the bottom rail at the point at which you wish to restrict the slider and inserting an appropriate sized bolt will suffice. Additionally, to prevent the slider being lifted, fit a wooden block of a suitable depth into the track above the slider. When used in conjunction with stay locks or child safety locks on the primary glazed window, security is enhanced further.
Leaded windows
These are not secure unless you fit secondary laminated glazing, polycarbonate sheeting, or internal grilles.