security
Page 57
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Scrutinize your doors
by Inspector K. W. Norman,
Crime Prevention Section, New Scotland Yard.
• When the general security of premises becomes a matter for consideration, the standard of door locks in use is often questioned. It is always advisable in all but the least hazardous situations to fit locks conforming to British Standard 3621 /1963 which is the specification for thief-resistant locks for hinge doors. One word of warning: when the locking style of a door is mortised to receive a mortise lock, it follows that the strength of the door at this point is considerably reduced.
Too much importance cannot be attached to the fact that before locks receive attention the suitability of the door itself and the support it receives from its door frame should be scrutinized. As in all matters of security, the standard of both door and lock will need to be matched to the nature of the risk and will be affected in some degree by the amount of exposure to public view that the door normally receives especially when the premises are unoccupied.
Because a door appears robust and well fitting, it should not be overlooked. It would be fair to say that many doors are constructed of materials and in such a manner as to make them suitable for purposes of privacy but certainly not security. Apart from deterioration brought about by the weather and continual abuse, such as forced slamming, hinges become defective and mortise joints broken resulting in a complete breakdown of security value.
In high-risk situations, consideration should be given to single or double-metal lining of the door. Two hinge bolts should be fitted to the hinge side of the door at the top and bottom thirds and an additional hinge fitted in the centre division. The door can then be covered with sheet steel no thinner than 16 swg and lapped over the leading and rear edges of the door.
Metal cladding
The metal cladding should then be secured to the styles, rails and mountings and any other solid timber parts of the door's construction, with coach bolts at 12in. intervals with nuts on the inside and burred over. In addition, clutch-headed screws or screws otherwise defaced to make them non-return, should be used to further secure the steel to the door at 4in. intervals.
In some situations it may be advisable to double line the door in which case sheet steel is used on both exterior and interior surfaces, and secured together through the wood by coach bolts at 6in. intervals with nuts on the inside and burred over.
If it is found that the frame requires strengthening this should be done by fixing it in the surrounding brickwork by countersunk Rawlbolts at 12in. intervals and then covering the exposed surfaces with angle iron which should be secured to the frame with non-return screws at 4in. intervals.