US3503837A - Reinforced bitumen covering with sheet-metal protection - Google Patents

Description

March 31, 1970 'P. L. CHEVAL REINFORCED BITUMEN COVERING WITH SHEETMETAL PROTECTION Riled March 24, 1964 United States Patent O 3,503,837 REINFORCED BITUMEN COVERING WITH SHEET-METAL PROTECTION Pierre Louis Cheval, Courbcvoie, France, assignor to Societe Nouvelle Siplast, Paris, France Filed Mar. 24, 1964, Ser. No. 354,324

Claims priority, application France, Apr. 12, 1963,

931,444 Int. Cl. B32b 3/00 US. Cl. 161-116 2 Claims ABSTRACT OF THE DISCLOSURE The following abstract is proposed:

A roof-covering material comprising in association an unbroken strip or band of metal of high coeflicient of expansion, e.g. aluminium, and a layer of bitumen, wherein at selected spaced intervals the band or strip of the material is formed with transverse zones or lines of weakness of the metal, or of its connection to the bitumen layer, in order to facilitate the release of stresses of the metal in relation to the bitumen covering when the material expands.

It is current practice to use reinforced bitumen coverings self-protected by aluminium sheets for rendering roofs and roofing watertight. A covering of this character consists as a rule of a bitumen sheet having a strength of 0.6 to 1 lb. per sq. ft., reinforced with a support-forming textile fabric such as cloth or fiberglass sheet, and comprises on its top face a plain or crinked aluminium sheet adapted to protect the bitumen against ageing.

This covering is characterized by a known draw-back when it is applied to a roof subject to substantial changes in temperature and comprising a strong heat insulation, due to the unequal expansion of the strips of metal lining, especially if these are relatively long, for instance several yards long.

In fact, if at some places the temperature of the aluminium sheet rises to, say, 122 to 149 F. (50 to 65 C.), this temperature increase is transmitted to the underlying layer of bitumen which becomes softer, without any possibility for the heat to be dispersed due to the presence of the heat insulation. As a result, at these specific places the aluminium sheet expands and becomes subject to compressive stress as long the bitumen remains at a low temperature, that is, very rigid, and counteracts the aluminium expansion. From a temperature at which the bitumen loses its high viscosity characteristics the aluminium sheet expands and is elongated, but due to the unequal heating of the different surface zones of the roof wrinkles develop between the hot zones and the colder zones, the elongation occurring in the hot zones to a sub stantial extent which may become permanent, and being prevented, as already explained hereina-bove, in the cold zones.

Various attempts have already been made with a view to avoid these inconveniences by using special bitumens, cold-drawn aluminium, or by making different types of wrinkles or creases in the aluminium sheets, but without any really satisfactory result.

Another proposal consisted in creating expansion joints by simply cutting the aluminium sheets at regular intervals, but this solution is equivalent to breaking the continuity of the protective lining of the bitumen covering by the aluminium sheet and to forming incipient lines of fracture in the covering proper, thus obviously impairing the watertightness of the assembly.

With this invention the formation of wrinkles or creases in the aluminium sheets, at spaced and suitable intervals,

3,503,837 Patented Mar. 31, 1970 ice ing a high coefficient of expansion) as a consequence of an increase in the roof temperature, is avoided by forming in the aluminium sheets, at spaced and suitable intervals, mechanical breaks of continuity adapted to relieve stress in the aluminium sheets with respect to the bitumen layer on which it is applied.

These mechanical breaks of continuity may be obtained along lines extending at right angles to the direction of expansion by thinning out the aluminium sheet or altering the adherence between the bitumen covering and the aluminium.

This adherence modification may be obtained:

Either by avoiding at spaced and suitable intervals any adherence between the aluminium sheet and the bitumen covering by using an antiadherent or adherence-inhibiting product along lines extending at right angles to the direction of expansion of the metal;

Or by reducing the forces of adherence of the metal on the covering along said lines by impressing on the aluminium sheet, prior to its fixation on the covering, strips of soft bitumen having a softening temperature inferior to that of the bitumen used for making the covering.

In order to afford a clearer understanding of this invention, various forms of embodiment thereof will be described hereunder with reference to the accompanying diagrammatic drawings showing typical examples of means according to this invention for absorbing the aluminium expansion in a reinforced bitumen covering selfprotected by a layer of metallic foil or sheet of aluminium or other metal having a high coefiicient of expansion.

EXAMPLE I A covering may consist of strips for example 30-feet long assembled along their major sides, each strip comprising a bitumen covering 1 (FIGURE 1) lined on one face with a thin aluminium sheet or layer of metallic foil 2, for example 0.003" thick, creased or not, these strips being for example 3 feet wide and welded by juxtaposition with a 2-inch overlap, according to the conventional technique, the aluminium expansion question arising in the longitudinal direction only, not in the transverse direction.

In their longitudinal direction these strips are formed with thinner portions 3 obtained by rolling the aluminium to reduce its thickness from 0.003" to 0.0008", these thinner portions being about 0.08 wide and spaced about 16 inches apart and connected by connecting portions which are not reduced in thickness.

EXAMPLE II FIGURE 2 shows in section a strip 1 provided, on its top face on which the aluminium sheet 2 is to be applied, with transverse portions 5 of a suitable nonadherent or adherence-inhibiting product such as silicone, thereby altering along these portions the adherence of the metal on the bitumen covering.

EXAMPLE III FIGURE 3 illustrates a metal sheet having formed on its inner face along spaced transverse portions a plurality of strips coated with adherence-inhibiting product such as soft bitumen 4. This bitumen may be petroleum bitumen having a softening temperature of the order of 122 F. (50 (3.).

In all these examples, the transverse portions formed on the aluminium sheet transversely to the'direction of expansion thereof break the continuity of the adherence of the aluminium or other metal on the bitumen and permit of reducing to reasonable limits the effects of heat expansion without creating wrinkles or swellings likely to impair the watertightness of the covering.

FIGURE 4 illustrates diagrammatically a typical eX- ample of an arrangement for preparing coverings of the type described in Example III hereinabove.

A web of fiberglass fabric 6 is delivered continuously at a regular rate from a feed roll 7, and a web or strip 8 of aluminium or any other suitable metal having a high coefiicient of thermal expansion, such as zinc or copper, coloured or not, is paid out from another roll 9 in synchronism with the fiberglass fabric 6 and the two webs are applied against each other as they pass over a cylinder 16; molten bitumen is fed into the vat 10 and adheres to both sides of the fiberglass fabric web to form the composite reinforced bitumen covering 1 of a thickness varying as a function of the bitumen feed and of the peripheral speed of the rolls delivering the fiberglass fabric and the metal.

The metal sheet may be wrinkled or corrugated by moving between a pair of rollers 11, 12; its inner face is provided with spaced transverse strips 4 of soft bitumen, the relative spacing of these transverse strips or portions is adjustable in relation to the direction of feed; this deposit is effected by means of blades or doctors 14 mounted on the outer periphery of a cylinder 15 revolving at a speed corresponding to that of said'rolls, these blades or doctors 14 dipping by turns into the container 13 fed with soft bitumen.

Thus, the adherence of the metal strip on the bitumen covering reinforced by fabric or fiberglass cloth is discontinued along the transverse portions where the metal strip is coated with antiadherent or adherence-inhibiting product.

The composite strip thus obtained is subsequently treated in the conventional manner by applying thereto the usual cooling, sandblasting and lateral trimming steps.

It is advisable to combine the aforesaid adherence-in- Y hibiting transverse lines with the creasing or wrinkle lines 17 (FIGURE 1) for these last-named lines would not provide alone the desired result.

What is claimed is:

1. An improved laminated roofing material comprising, a bitumen layer, a continuous sheet of metallic foil covering one side of said bitumen layer, said sheet of metallic foil comprising a plurality of longitudinally extending, spaced connected portions and a plurality of longitudinally extending intermediate, connecting portions adhesively adhered to said bitumen layer, means comprising structure built into said roofing material coextensive with the first-mentioned portions causing the first-mentioned portions in use to contract and expand relative to said bitumen layer differently than said connecting portions, said means comprises a series of longitudinally extending spaced portions composed of a bitumen composition softer than the coextensive bitumen layer and disposed substantially coextensive with said first-mentioned portions of said foil and between said foil and said bitumen layer and said portions being coextensive with said bitumen layer.

2. An. improved laminated roofing material according to claim 1, in which said means causing the first-mentioned portions of said foil to contract and expand difierently than said connecting portions comprises a series of longitudinally extending portions of silicone between said foil and said bitumen layer and nonadhered to said foil, said portions of silicone being substantially coextensive with said first-mentioned portions of said foil.

References Cited UNITED STATES PATENTS 2,289,699 7/1942 Doe 161-117 3,095,339 6/1963 Craig 161-146 2,286,120 6/1942 Snyder 161224 2,373,039 4/1945 MacChesney 161l16 2,732,886 1/1956 Andreoli et a1. 161-224 2,975,808 3/1961 Schilder 1611l7 2,985,554 5/1961 Dickard 156-289 2,139,882 12/1938 Cunnington 16l--224 MORRIS SUSSMAN, Primary Examiner US. Cl. X.R.

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