Fig. 260. Fibrous Plaster slabs.
Messrs. Wilkinson have a system shown in section Fig. 260 by which existing wooden floors can be converted into " slow-burning constructions."
The ceiling and the pugging of the floor are formed of non-inflammable fibrous plaster slabs, 7/8 inch thick, the latter laid in the usual way upon wood fillets fastened to the joists and secured by plaster fillets above.
The fibrous plaster slabs are made of coke breeze and plaster on a basis of cocoa-nut fibre. They make a very light floor which does not require such thick supporting walls as do floors of concrete (see also fireproof plastering, p. 135).
The systems of fireproof flooring that have been introduced or proposed at different times are almost innumerable. The shape of the girders has been varied in every possible way, and all sorts of materials used in connection with them.
Several new forms have been proposed during the last few years, but many of them have not been fully tried. The subject is one of great importance, and will no doubt be greatly developed.
As above stated, it is necessary that all iron work should be protected from the fire by some non-conducting substance. Tigs. 261, 261a show the method adopted by Messrs. Dennet and Ingle for encasing both columns and girders in concrete.