The floor or upper surface can be finished in the material itself, at a small cost, equal to stone in durability and appearance. When covered with kamptulicon or other similar material a floor at once noiseless to the tread and free from vibration is obtained. These qualities are, for banks and other public offices, very important desiderata. The arch may, of course, if preferred, be paved with any other material, such as stone, tiles, asphalte, or cement.
Floors formed in the simple manner described are excellent in a sanitary point of view. They are clean, non-absorbent, and are non-conductors of sound and heat. These qualities particularly recommend them for adoption in hospitals, unions, barracks, and other large buildings; while for houses of the artisan class, especially in crowded districts, no other method of construction presents so many advantages.
If a flat ceiling is required, ceiling-joists are fixed to the lower flanges of the iron girders, and lathed and plastered in the ordinary manner (diagram D). It is generally preferred, however, in buildings of a public character, such as banks, offices, &c., to leave exposed the lower flanges of the iron girders. This is the most constructional mode of treatment, and by the judicious application of coloured decoration a very effective ceiling is obtained. The ceilings of the bedrooms at Kelham Hall, Notts, a building designed by Sir Gilbert Scott, are finished in this manner. This mansion was made thoroughly fireproof on its re-erection nine years ago, after the destruction of the former building by fire. The ceilings of the reception-rooms are formed by groined vaults of considerable rise springing from carved stone corbels. The roof is protected from fire by light segmental vaults springing from wall to wall.
When used for flat roofing—for which purpose the strength and freedom from vibration of the construction renders it particularly adapted—a layer of asphalte or other impervious coating is required to protect the arches from the weather.