US2373317A

US2373317A - Roof covering

Info

Publication number: US2373317A
Authority: US
Inventors: Thomas A Lawson
Original assignee: Individual
Current assignee: Individual
Priority date: 1942-05-02
Filing date: 1942-05-02
Publication date: 1945-04-10
Anticipated expiration: 1962-04-10

Description

T. A. LAWSON ROOF COVERING April 10, 1945.

Filed May 2, 1942 wwwa;

. INVENTOR THOMAS ,4. An/.90N

ATTORNEY Patented Apr. 10, 1945 UNITED vs'rA'ifaws, PATENT AoFFlcr.

ltooF covEmNG Thomas A. Lawson, San Francisco, Calif.

Application May 2, 1942, serialNc. 441,491 z claims. (ci. s-a5) This invention re to improvements in l-'toof Coverings and mo particularly to composite fireproof shields for roof coverings.

Among the objects of the invention isthe provision of a stratified shield composed of noncombustible granular minerals, adapted to be easily applied to conventional hat roofs.

. Another object is the protection of theunderlying roof with a friable shield that may be easily removed to permit access to any portion of the roof for repairing. v

Another object is the utilization of easily obtainable materials in the composition of the shield to facilitate its application to the roof with out specialized skill and at a reasonable price.

A further object is the accomplishment of the above objects with minimal weight per square foot of roof area.

Other objects and advantages will appear as the description progresses,

In the specification and the accompanying drawing the invention is disclosed in its preferred form. But it is to be understood that it is not limited to this form because it may be embodied in modifications within the spirit of the invention as defined in the claims following the description.

In the one sheet of drawings:

Fig. 1 is a. fragmentary detail of a portion of a roof adjacent the side wall, having this invention applied thereto and shown in vertical section. i

the upper portions of the surrounding wall.

The conventional roof covering consists of the heavy fiber sheets I impregnated with water proofing, such as vfluid asphalt, tar or the like. The edge of the first side sheet is folded up the side wall and attached to the coping board 4. The edge of the next sheet 5 is overlapped to form a seam at 5' that is nailed to the sheathing.

The top surface of the fiber sheets is then given a heavy coating of tar I brushed on in a manner to seal all the seams 5' and the upper edges of the tar coating 6 is still i'iuid or tacky a layer of/ coarse and ne ygravel 'I is spread evenly over the treated area. The gravel adhering to the coating 6 tends to anchor all the gravel against displacement by passing winds. The above describes a conventional flat gravel roof, having just enough inclination to provide drainage. There are various modifications of the above, such as prefabricated sheets having a top coating of fine slate aggregate instead of the pebble'gravel l, to which the present invention is equally applicable.

The heat from a glowing cinder or rebrand falling upon such a roof will release volatile gases from the tarr coating 6, feeding the flames until the fabric sheets 5 are ignited and the fire reaches the underlying sheathing l.

The present invention consists of the composition and the method of applying a composite fireproof shield for any conventional form of dat roofing. The first step in the method is to distribute evenly over the surface of the gravel layer l, a mat of asbestos fiber, rock wool or similar Y pairing.

the sheets where they join the coping I. While non-inflammable fibrous material. This fluffy layer is then tamped or patted down until it penetrates into the interstices in the gravel layer l, beneath. A thin layer 9 of Portland cement or the like, is then sprinkled evenly over the mat 8 and sprayed lightly with water to form a thin skin of neat cement on the surface which gradually seeps into the fibers of the mat, but not enough to destroy the friability of the mat when the cement sets, but Just enough to integrate the fibers to overcome the natural iiufliness. The layer of gravel or fine aggregate Ill is then evenly distributed over the top of the mat 8. A layer of Portland cement is thenevenly distributed over lthe surface of the top gravel layer l0 and lightly sprayed with water, just enough to carry the pulverized cement down into the interstices in the .gravel layer I0, and leave a cementitious glaze on its top surface.

The fibrous mat; B need not be. over to 1/2 an inch thick. It is mechanically keyed tc the gravel layer l, but it does not adhere thereto, because of the poor adhesive qualities of Portland cement. This is desirable because it enables the easy removal of any portion of the reproof shield 8-9-I0 to expose the roofing l-'B--S for re- The reprooing shield 8-9-l0 is not intended to contribute to the waterproofing of the roofing beneath, except to an incidental extent. It has the advantage of thermal insulation, preventing the loss of heat from beneath the roof, and against the penetration of sunheat from above.

Where the coping such as I, is inammable it is good practice to cover it with metal or asbestos sheeting such as Il, having its lower edge I2, folded outward beneath the mat l. Such sheeting should be continued upward and over the top of the coping and secured by tacking or adhesion.

The porous mat l formed in the manner described, is superior to prefabricated sheets of asbestos or other non-inflammable material, because it is not subject. to lifting by winds blowing across it. A more dense layer will tend to lift off the roof surface due to suction and be torn or displaced. l

If preferred the ber forming the mat 8 can be premoistened with water and spread over the roof like plaster. This is advantageous while working in windy weather.

Having thus described this invention what is claimed and desired to secure by Letters Patent is:

1. The method of reprooiing a roof having a conventional covering consisting of superposing a continuous non-adhesive mat of brous noninammable material on said covering; applying a coating of Portland cement to the top surface of said mat; superposing a layer of loose gravel on top of said mat; applying a coating of dry Portland cement on top of the gravel on said mat; and then moistening said structure with Water.

2. In combination with a roof having conventional gravel roof covering; a continuous shield composed of noninlammable fibrous material impregnated with Portland cement to form a nonadhesive friable mat overlying said covering; a layer of Portland cement applied to said mat: and a top layer of gravel embedded in said layer of cement.

THOMAS A.. LAWSON.