Static structures (e.g. – buildings) – Sheetlike element assembled parallel to existing wall,... – Element spaced from wall – ceiling – or floor and held by...
Patent
1988-07-19
1990-07-24
Murtagh, John E.
Static structures (e.g., buildings)
Sheetlike element assembled parallel to existing wall,...
Element spaced from wall, ceiling, or floor and held by...
52417, 52573, 52630, 52537, 52747, 52748, E04D 332, E04D 330, E04C 232
Patent
active
049427121
DESCRIPTION:
BRIEF SUMMARY
This invention relates to roof coverings and, in particular, to roof coverings which are suitable for use on flat or shallow angle roofs (that is, roofs which are horizontal or slope at a shallow angle, typically less than 15.degree., to the horizontal).
The invention is concerned, more especially, with roof coverings of sheet-like form which are intended to be laid on a substantially continuous substrate, for example a roofing deck, to provide a waterproof skin to a roof. It is known to produce roof coverings in the form of panels which, in use, are secured at their edges to the substrate either directly or via a layer of insulating material, for example a rigid foam. The panels are normally made of a plastics material, often reinforced with fiber and typically have a very high coefficient of expansion and a comparatively low elongation at break particularly at temperatures below 10.degree. C. A typical general purpose polyester resin reinforced with chopped strand glass mat would have an elongation at break of less than 0.2% at 10.degree. C. Failure to provide some means of accommodating expansion and contraction of the panels relative to the substrate often results in cracking of a portion of the panel, particularly when laid over large roofs, causing the roof to leak.
Problems due to expansion and contraction of roof coverings are also encountered when the coverings are formed from other materials, for example metal or asphalt.
The present invention provides a roof covering suitable for use on flat or shallow angle roofs, the covering being of sheet-like form and having at least one raised region in the sheet, the raised region merging into undulations at the border surrounding the raised region.
The undulating border and raised region together provide a means by which the covering can, by changing its shape, accommodate expansion or contraction. For example, if the temperature of the covering increases without there being a corresponding expansion of the substrate, the undulations will become more severe and the raised region rise up further. Conversely, if the temperature of the covering reduces without there being a corresponding contraction of the substrate, the undulations will become less severe and the raised region will shrink in size.
The raised region preferably has a curved configuration in cross-section and is more preferably of essentially inverted-dish shape. "Dish shape" as used herein is not limited to shapes which are of part-circular cross-section. Alternative shapes may be used, including for example, a raised region generally dish-shaped but having a depressed central portion or a flattened central portion, and a raised region comprising a series of ridges and depressions each of which surrounds a common point. Regions having a depressed central portion or ridges and depressions are less advantageous in that water may collect in the depressed portion or between the ridges as the case may be; raised regions having a flattened portion are less advantageous in that the flattened central portion has reduced efficiency in accommodating expansion or contraction by altering its shape.
The covering may be in the form of a panel.
In an embodiment of the invention, the covering comprises a plurality of raised regions of relatively large subtended volume, each of which merges generally downwardly into a surrounding undulating border made up of a series of smaller subtended volume undulations. There may be a plurality of securing points spaced apart around the border of the, or each, raised region, or of a group of raised regions.
Advantageously, the length and width of the covering measured along undulating edges and following the surface of the covering are approximately the same as the length and width respectively of the covering measured across the centers of the larger volume raised region or the centres of the raised regions following the surface of the covering. Most advantageously, for a unit length of the covering in any direction the distance measured in the direction of that unit le
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patent: 4018016 (1977-04-01), Zale
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