US2122747A - Roofing felt - Google Patents

Description

July '5, 1938. KIRSCHBRAUN ROOFING FELT Filed Dec. 31

I lNVENTOR Lester Kzr'schbraun ATTORNEY Patented July 5, 1938 I I UNITED STATES PATENT OFFICE ROOFING FELT Lester Kirschbraun, New York, N. Y., assignor to The Patent and, Licensing Corporation, New York, N. Y., a corporation of Massachusetts Application December 31, 1936, Serial No. 118,477 6 Claims. (Cl. 108-7) This invention relates to improvements in the much as the steam occupies a volume 1700 times construction of roofing felts particularly for use greater than did the water from which it was in so-called built-up roofs. formed, it can readily be seen that the substan- Built-up roofs have long been employed in the tial volumes of steam produced from the presence building industry both for new construction and of even 2 to 3% of moisture in the felt, will be 5 for reroofing' of old buildings. This type of roof. suflicient to hold the upper felt layer from the when laid upon a wooden roof deck, is convenasphalt coated lower layer thus preventing good tionally composed of a dry laid foundation adhesion of the plies of felt and forming pocksheathing of any suitable material secured by ets therebetween, the pockets often appearing nails or the like directly to the deck. Upon as blisters on the surface of the felt. The un- 10 the sheathing one or more plies of felt are laid rolling of the felt onto the hot asphalt also enwith asphalt layers or moppings therebetween trains air therebetween, such air further preand between the foundation sheathing and the venting proper bonding of the felt layers and lowermost ply. As many coatings of asphalt and otherwise adding to the deleterious effects of plies of felt may be provided as are necessary the entrapped steam. 15

'to build up the roof to the desired thickness. The principal object of my invention is to pro- The outermost ply may be covered with a layer vide an improved form of felt for built-up roofs of asphalt and a suitable surfacing material or the like. In accordance with my invention may be partially embedded therein. In the case the felt is provided with vents to permit the eswhere the roof is built up from a concrete deck cape of entrapped air and. steam in the use of the dry laid foundation sheathing layer is usually these felts in laying built-up roofs. omitted and the initial felt ply laid directly on It is of primary importance that the above the deck and secured thereto by a spot mopping stated object of my invention be attained withof asphalt. out weakening the felt sheets by the removal of It has been found that in these so-called built substantial portions of the material thereof and 25 up roofs numerous separations or delaminations without altering the sheets in such a manner as of the superposed sheets frequently occur, such to permit substantial quantities of the asphalt 4 separations often being evidenced on the surface of the mopping layers to ooze to the surfaces of the roof by the appearance of raised portions of the sheet where it would be picked up by the or blisters. Any separation of the constituent shoes of workmen. 30 layers of the roof lessens the durability and It is therefore a further object of the invention waterproofness thereof and may result in crackto produce a felt for built-up roofs or the like ing of the felt at the points where the blisters in which vents are provided to permit the escape occur, particularly when the roof is walked upon of entrapped air and steam but without removal in the subsequent building operations, the crackof any substantial portion of the felt and with- 35 ing of the felt permitting moisture to enter beout permitting passage of a substantial amount tween the laminations of the roof structure and of asphalt to the outer surface of the felt. thereby cause rapid deterioration of the roof. It A more specific object of the invention is to has been determined that such separation of the. provide a roofing felt having openings therein 40 piles of felt is frequently caused by steam, gento permit the escape of entrapped air and steam 40 erated bythe hot asphalt from the moisture conand having means formed from the body of the tained in the felt, and by air entrapped between felt to close the openings. the layers as the felt is unrolled onto the hot The foregoing and other objects of the invenasphalt. The asphalt saturated felt, as it is de'- tion as well as numerous advantages thereof will livered for use, generally contains from 2 to 3% more clearly appear from the following descrip- 45 of moisture. In a 30 pound sheet this means tion of my invention. that from 1% to pound of water per 100 square My invention in its generic form resides in the feet of felt will be contained therein. The approvision of tabs in the felt sheets which nor- Dlication mopping 0f e hot a pha t onto mally lie in the plane thereof but are capable the surface of a felt layer converts the contained 'of yielding under pressure to expose openings 50 water largely into steam which inturn induces a through the sheets. In its preferred form my frothy ebullient condition of the asphalt and invention resides in the formation in the felt the second layer of felt being laid upon the asof uniformly distributed pairs of short cuts or phalt while it is in this condition entraps the incisions extending through the felt, the cuts generated Stea b tween the felt layers- InaS- of each pair meeting at an acute angle and thus 55 2. forming pointed tabs which, when displaced from the plane of the felt, expose correspondingly shaped openings. A sheet of felt embodying by invention, when laid over a layer of hot molten and frothy asphalt in a conventional manner, has the tabs thereof displaced from the plane of the sheet by the pressure exerted by the entrapped steam and air ted to escape through the resulting openings. conventionally, as the felt is unrolled on the asphalt layer it is pressed into the asphalt by an operation known in the art as brooming which consists in brushing the sheet with a stiff broom or the like. Where felt, embodying the preferred form of my invention, is' employed in the construction of built-up roofs the brooming operathe apertures.

tion in addition to its usual functions will, after the escape of the entrapped steam and air, return the displaced tabs once more into the plane of the felt sheet where they will be cemented down by the asphalt which tends As is apparent from the foregoing description of the construction and use of this invention, prevention of blistering by entrapped steam and air is obtained but the strength of the completed roofing structure is not decreased and little asphalt is exposed on the'surfaces of the felt sheets in their application to the roof.

Asphalt impregnated felts when in rolled form often exhibit a tendency toward adhesion between the several convolutions of the roll, particularly" when the feltis at all oversaturated with the asphalt. This tendency is generally insufllcient to cause material trouble in felts previously employed. Where however, the tabs of the present invention are present, difficulty may arise due to the adhesion of such small tab areas to the underlying convolution of the rollof felt if the tabs point towards the outer end of the rolled sheet. In such case'if there is even a slight adhesion between the tabs of one convolution'and' the next underlying convolution, the point of the tab will be carried with the underlying convolution of the roll as the felt is unrolled and a-tearing action on the base of thetab will result which, in many cases, may be sufficient to tear the sheet. Furthermore, in the brooming of the felt it is desirable that the tabs be so arranged that the normal operative stroke of the broom will pass from the base of the tab to its point in order that the tab may be pressed into the plane of the felt rather than be raised therefrom. It is therefore preferable to so form the tabs (and their comple- 'mentary openings) that their points extend in a' direction toward the roll as it is being unwound.

The invention will be more fully understood by reference to the accompanying drawing in which:

Figure 1 is a perspective view, of a roll of roofing felt embodying a preferred form of my invention, partially unrolled;

Figure 2 is a fragmentary perspective view of asheet of the roofing felt of Figure- 1, on an enlarged scale;

Figure 3 is a perspective trating the application thereto of the roofing felt of this invention; and r Figure 4 is a sectional view of the roof taken on a line 4-4 of Figure 3.

In the drawing, I represents a sheet of asphalt impregnated felt having formed therein amultiplicity of pairs of short cuts or incisions 2, each pair forming between them a triangular tab 3.

As shown in Figures 1 and 2, the tabs are placed whlch is thereby permitto ooze through 7 view of a roof illuslapping. A coating of hot molten asphalt I may be spread or mopped onto the surface of the sheathing layer and, while the asphalt is in the hot molten condition, sheets of roofing material, embodying the cuts and tabs of the present invention, unrolled thereon in successive overlapping relationship with .the portion of each sheet to be overlapped receiving a mopping of the hot molten asphalt so that in no place will felt touch felt. The sheets are pressed into the hot asphalt by means of stiff bristle brooms or other roofing implements. As the felt is laid, the steam generated by'the action of the hot asphalt on the moisture content of the felt and also any air entrained between thefelt and the asphalt as the felt is unrolled, will force the tabs out of the plane of the sheet to a position as shown in Fig. 4, and escape through the openings thus exposed. As many plies of the felt embodying my invention may be laid as is necessary to build up the roof to the desired thickness. The outermostlayer may be provided with a mopping of asphalt and a suitable surfacing'material may be partially embedded therein. In the case where the roof is to be built up from a concrete or similar deck the operations are the same except that the dry laid foundation sheathing layer is usually omitted and the initial felt ply spot mopped directly onto the roofdeck. As is readily apparent the advantages and new results, flowing from the use of the v felt embodying my invention, will be obtained. irrespective of the particular built-up roof construction employed.

As clearly shown in Figure l, the triangular tabs and their corresponding apertures are preferably placed so as td'point toward the roll of felt as it 'of the adjacent. convolution of the felt from the tab and little likelihood of tearing of the felt will result. As previously stated, the unrolled felt is pressed into the asphalt coating by a brooming operation which consists in brushing the felt with a stiff bristle brush or the like. By. pointing the tabs in the direction of the unrolling of the felt the brooming of the felt into the hot asphalt will return the tabs to their original location within the plane of the sheet where they will be cemented 1 down by the asphalt.

A preferredforr'n for the tabs is'illustrated in the drawing and above description. It is to be understood'however tha't the objects of the invention may lie-obtained by employing tabs having other configurations.- For example, in place of, the triangular tabs shown there may be used tabs of semi circular or quadrilateral shape. It will thus be apparent to those skilled in the art that numerous variations'and changes may be made without departing from the spirit of my invention as defined by the appended claims.

What I claim is:

l. As an article of manufacture, a sheet of rooting felt, of indefinite length for the construction of built-up roof coverings and the like, the sheet comprising a body portion and a plurality of tabs, the tabs being individually of small area in relation to the area. of the sheet and formed from the material of the sheet and integrally therewith, the tabs being displaceable from the plane of the body portion to permit the escape of entrapped gases and the like occurring in the laying of the roof covering.

2. As an article of manufacture, a roofing sheet of indefinite length for the construction of built-up roof coverings and the like, the sheet having a plurality of pairs of short incisions therethrough, the incisions of each pair forming a tab displaceable from the plane of the sheet to permit the escape of entrapped gases and the like occurring in the laying of the roof covering.

3. As an article of manufacture, a convoluted sheet of roofing felt, of indefinite length for the construction of built-up roof coverings and the like, the sheet comprising a body portion and a plurality of uniformly distributed pointed tabs of individually small area in relation to the area of the sheet, the tabs being formed from the material of the sheet and integrally therewith,

, the tabs being displaceable from the plane of the body portion to permit the escape of entrapped gases and the like occurring in the laying of the roof covering.

4. As an article of manufacture, a roofing felt for the construction of built-up roof coverings and the likehaving a plurality of pairs of incisions therethrough and distributed throughout the area thereof, the incisions of each pair diverging from .a point common to the pair and forming between them a substantially triangular tab with its base integrally joined to the felt, the tabs being displaceable from the plane of the felt to permit the escape of entrapped gases and the like occurring in the laying of the roof covering.

5. As an article of manufacture, a roll of roofing felt for the construction of built-up roof coverings and the like, the felt comprising a plurality of tabs, each tab being formed from the felt and integrallyjoined thereto at its base and extending from its base in a direction as to point toward the roll upon the unwinding of the roll, the tabs being displaceable from the plane of the felt when the felt is unrolled to permit the escape of entrapped gases and the like occurring in the laying of the roof covering.

6. As an article of manufacture, a roll of roofing felt for the construction of built-up roof coverings and the like, the felt having a plurality of uniformly distributed pairs of incisions therethrough, the incisions of each pair diverging from a point common to the pair and forming tab integrally connected between them a pointed with the felt at its base and extending from its base in a direction as to point toward the roll upon the unwinding of the roll, the tabs being displaceable from the plane of the felt when the felt is unrolled to permit the escape of entrapped 7 gases and the like occurring in the laying of the roof covering.

LESTER KIRSCHBRAUN.

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