In these days of advanced construction methods, embodying the most scientific combination of materials and labor to effect the splendid edifices daily being fabricated in this growing city, the matter of time-proof and fireproof root construction should be particularly interesting to all classes identified with the upgrowth of our city. The selection of a composite, all-mineral roof covering adaptable to any class or style of structure, which combines naturally the above mentioned requisites for ideal results, is found in the built-up asbestos roof, a combination of Trinidad lake natural asphalt (mineral) and pure asbestos felts (stone). Everyone is familiar with the ordinary street pavement, which is approximately 90 per cent mineral (crushed rock) and 10 per cent asphaltic binders. The lake natural asphalts are recognized as the most lasting water and weather proof binder for the composite mineral pavement. This is due to the extreme stability and ductility of Trinidad asphalt, which has in its natural state resisted for untold centuries the destructive weather conditions of the tropics. Asbestos felts, 95 per cent, pure (fibrous material), weighing not less than 15 per cent, to the square, are impregnated with Trinidad asphalt, completely coating each fiber, and filling absolutely the minute interstices in the asbestos fiber. Asbestos felts are non-tubular, and therefore have no capillary attraction. The exposed roof surface is finished with an unimpregnated sheet of pure asbestos felt, completely sealing from the action of the sun the asphalt below in the impregnated plies and the moppings of asphalt between the plies. Therefore the asphalt impregnation is permanent and cannot be drawn out by action of the rays of the sun, which quickly destroy and oxidize the asphalt saturation in wool felts through capillary attraction. This complete protection of the asphalt, the waterproofing agent of the roof, is of vital importance, as far as regards eventual upkeep expenses connected with the finished roof; eliminating entirely the costly renewal of waterproofing by painting, absolutely necessary wherever wool felts saturated are exposed to sun attack. The white surface reflects the sun’s rays to a surprising degree, reducing the temperature of the roof fabric from 18 to 30 degrees in hot weather. This feature is, in itself, important, aside from the resultant cooler building, insomuch as ordinary asphalts in common use have a melting point of approximately 135 degrees, at which temperature they lose their binding, cementicious qualities entirely. Such a temperature is often reached on the surface of a roofing fabric exposed to direct sun heat during the summer months. The most commonly known property of asbestos is its imperviousness to destruction by fire, and it has been demonstrated many times that fire cannot get through an asbestos roof from the surface. Internal fires will not affect it until roof boards are entirely consumed, allowing the roofing to fall. Asbestos roofing applied directly over a concrete roof slab will waterproof and finish with an indestructible weather covering the modern absolutely fireproof structure.