WINDOW LOCKS
Where windows are not required to be opened, they may be screwed permanently shut. Security screws shall be used where this is to be done from the outside, and the heads buried and filled over.
The security of all ground floor and all accessible windows (e.g. from a flat roof)shall be considered.
Opening window sashes that are over 600 mm high or wide should be fitted with a multi-point locking system or two window locks with removable keys. Sashes less than 600 mm need only be fitted with a single lock.
Where a lock is to be fitted to a window care must be taken to ensure that the material to which the lock is fitted does not become weakened by fitting it too close to existing fittings.
Where a window is required for emergency egress then it shall not be fitted with any type of key lockable system. In this instance the window should be fitted with laminated glass.
Louvre windows
Urgent consideration should be made to replacing louvre windows as it will be difficult to obtain adequate security. If this is not possible then all the panes of glass (in louvre windows) should be securely fixed with a suitable adhesive, into their brackets or suitable grilles, bars, or shutters fitted. The use of plastic frame materials is not acceptable for a security application
Casement and Tilt/Turn Windows
Additional locks should be fitted to the frame parallel to the hinges on the opening sash.
Where the sash opening exceeds 600 mm two locks are required. For side hung sashes. the additional locks should be fitted approximately quarter of the height of the sash from the top and bottom of the sash. For top hung sashes the locks should be fitted approximately one quarter of the width of the sash from the left and right hand sides of the sash.
Vertical Sliding Sash Windows
Where the window opening exceeds 600 mm the locks should be fitted on, the centre rail of the
bottom sash, at approximately quarter points, or on the vertical frame of the upper sash, directly above the cross rail of the bottom sash.
Where there is a requirement for ventilation when the premises are occupied, sash widows can be
provided with a ventilation position to allow them to be opened a maximum of 100 mm when locked.
This is not recommended when the premises are unoccupied. The window should then be locked in the closed position.
SLIDING DOORS AND WINDOWS
All sliding doors and windows shall be fitted with anti-lift devices to prevent them being removed
from their tracks. Care should be taken to ensure such devices are fitted appropriately such that they do not to go inside the section of the frame when the door/window is closed. Some sliding door locks have an in built facility to prevent the door being lifted.
Additional locks fitted to sliding doors and windows should be fitted in such a manner as to ensure any force applied to open the door pushes against the lock fixing screws.
Wherever possible additional locks should be fitted to the top and bottom of the interlock of sliding doors and windows. However, there are some designs, which make this impractical.
Sliding doors/windows should not be locked in the ventilation position when the premises are
unoccupied.
GLASS
There are three main types of glass. These are:
„h Annealed Glass
„h Toughened Glass
„h Laminated Glass
Annealed, float or window glass is the most common type of glass used in buildings. It breaks easily and when broken forms large sharp fragments.
Toughened glass is a safety glass. In buildings it is usually found in ¡¥risk areas¡¦ which include doors and adjacent windows, low windows, bathrooms, landings etc. Toughened glass is manufactured by placing annealed glass into a furnace and quenching it on removal. This generates internal stresses within the glass. Typically toughened glass is around eight times stronger than annealed glass but when it breaks if forms a multitude of small fragments. It is also vulnerable to breakage with a sharp point such as a centre punch.
Due to the method in which it breaks, toughened glass offers very little security. Its value is as a safety glass.
Laminated glass consists of two thin layers of glass bonded each side of a transparent plastic (poly vinyl burate - PVB) interlayer. When the glass is attacked the glass layers fracture but remain in place, held by the PVB interlayer. Thus laminated glass offers both increased security and safety over annealed glass. Typical laminated glass found in domestic buildings consists of two layers of glass and one interlayer to a total thickness of 6.4 mm (soon to increase to 6.8 mm). However, the number of glass layers and interlayers can be increased to provide enhanced security such that, eventually, bulletproof glass can be produced.
The most common failure mechanism of laminated glass if for it to ¡¥balloon¡¦ and fall out of the frame under repeated impacts. However, the time taken for this gives and enhanced level of security over other types of glass
Excerts taken from The Guidelines for minimum security Requirements in Domestic property Edition 2, 20.03.02.
Published by the MASTER LOCKSMITHS ASSOCIATION
For more information visit their website www.Locksmiths.co.uk
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