The side and back walls are about 2 ft. thick, in hard brick laid in cement. At 9 inches from the inside of wall is a continuous rough iron grating of vertical bars, built in as a part of the solid wall. Hoop-iron is used in the horizontal courses. The entrance wall is 2½ ft. thick, but in other respects similar to the side walls.
The roof is formed of a brick arch 18 inches thick, with curved bars in the centre; and is covered with a layer of concrete.
The floor is brick and concrete as shown; with a layer of asphalte on the surface.
At the entrance to the room is a steel door of great strength, with two locks throwing 12 bolts, and with a fire-resisting chamber. Next to this is a pair of iron folding-doors, not fireproof; which, when open, lie within the thickness of the wall. There is next a wrought-iron gate opening inwards; the frames of the doors and gate being all connected by wrought-iron plates.
In the room itself, at the further end, is a fire-resisting iron and steel strong-room; and the space in front of it (sides, roof and floor) is lined with ½-inch iron plate, placed a slight distance from the wall to allow of an air-space between. The fittings are of iron; shelves on one side and cupboards on the other.
The cost of such a room complete, of the best materials and highest finish (including brickwork), would be about 1300l.
The following is a condensed description of a strongroom constructed a few years ago for a London bank, and which might serve as a model for others. The walls, two feet thick, are formed of hard bricks laid in cement, with hoop-iron worked in. The room is lined throughout with wrought-iron, ½ inch thick. There are two doors, the outer one a strong iron one, with two locks; and the inner one of combined iron and steel, of extraordinary strength, with two locks throwing ten bolts. A safe placed inside, weighing eight tons, and having twenty bolts, contains the cash and securities. An alarum in the resident clerk’s bedroom is attached to the inside of the strong-room, so that if the outer door be opened a gong is set going. A porter sleeps on a bed in front of the outer door, and by pulling a handle he can set the alarum off if necessary; and there is a watchman always on duty. With such a room as this, situated in a building constantly and carefully watched by trustworthy servants, robbery is made practically impossible.