Base sheet for retrofitting existing roofing

[0002] This application is based on Provisional Application Serial No. 60/113,791, entitled “Base Sheet For Retrofitting”, filed Dec. 22, 1998

[0003] The present invention relates to roof retrofitting, that is, replacing an existing roof with a new roof and, more particularly, relates to a base sheet for use in such retrofitting.

[0004] In the past, in order to retrofit certain types of roofs, such as gravel surfaced roofs, it has been necessary to either scrape the roofs smooth or lay a relatively rigid insulation or recovery board over the roof. Either of these approaches has proven to be time consuming and costly. In addition, when the roof is not scraped clean, the presence of gravel under the new roof can sometimes be visually apparent thereby impairing the aesthetics of the roof.

[0005] It is an object of the present invention to retrofit new roofing to existing roofing in a faster, more economical and more efficient manner without impairing the aesthetics of the new roofing.

[0006] The foregoing and other objects of the invention are achieved by employing a base sheet which includes a layer of flexible foam laminated to a support sheet.

[0007] The flexible foam cushions the underlying gravel, thus, preventing it from cutting through the new roofing and causing any leakage. Further, the flexible foam drapes over the gravel hiding it from sight, thereby resulting in a more aesthetic roof.

[0008] Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.

[0009] FIG. 1 is a sectional view of a retrofitted roof in accordance with a first embodiment of the invention; and

[0010] FIG. 2 is a sectional view of a retrofitted roof in accordance with a second embodiment of the invention.

[0011] Referring to FIG. 1, there is shown a first embodiment of the invention in which a new roofing 10 is to be installed over an existing roofing 11. The existing roofing 11, which includes embedded gravel 12, is installed on a wood deck 13. It should be noted that the existing roofing 11 is shown in FIG. 1 after it has been swept clean of any loose gravel. Accordingly, the only gravel shown in FIG. 1 is embedded gravel 12.

[0012] In accordance with the invention, a base sheet 14 comprising a support sheet 16 having a layer of flexible foam 17 laminated thereto is laid over the existing roofing.

[0013] Preferably, the support sheet 16 is polyester of a weight ranging from 100 grams per square meter to 300 grams per square meter and having a thickness ranging from ⅛″ to 1½″.

[0014] Preferably, the flexible foam layer 17 is ⅛″ to ½″ thick.

[0015] The base sheet 14 is laid over the existing roofing 11 with the flexible foam layer 17 in contact with the embedded gravel 12. The base sheet 14 is then fastened through the existing roof 11 to the deck 10 using suitable fasteners 18. Thereafter, the new roofing 10, which may be a built up roofing or a membrane sheet(s) is installed over the base sheet 14 in a conventional manner.

[0016] FIG. 2 shows a second embodiment of the invention in which the base sheet 14 and the new roofing 10 is installed over existing roofing 11 on a steel deck 19 via an intermediate insulation layer 21. Installation of the base sheet 14 on the existing roofing 11 in FIG. 2 is the same as that in FIG. 1 except that the base sheet 14 is fastened through the existing roof 11 to the insulation layer 21 rather than to the steel deck 19.

[0017] The new base sheet 14 allows a work crew to reproof gravel surfaced roofs 11 faster with less cost overall than either scraping the roof smooth or of laying a recovery board over the roof. Further, the flexible foam 17 cushions the embedded gravel 12, thus preventing it from cutting through the new roofing 10 and causing leakage. This is a common occurrence in prior art retrofitted roofs that consist of a base sheet and a roof membrane over a swept gravel roof. Further, the presence of gravel under a new roof can sometimes be visually apparent, i.e., the gravel impressions show on the new roof. In accordance with the present invention, the cushioning of the gravel by the flexible foam prevents such impressions.

[0018] Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.