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October 24, 2006

Steel Roofing with Attachments and Seaming

            There are several ways of grouping steel roofing types and one of the most common is by means of attachment to its supports.
            The term “through-fastened roofs” applies when the roof is attached directly with rivets or screws to the purlins. An indirect method of attachment is seen in standing-seam roofing which is done by the use of concealed clips that are placed into the seams. The standing-seam roof application is more technically defined as the “structural standing-seam metal roof system”. Although arguably a standing-seam roof, because it does not have concealed clips, the alternate style is simply called vertical-seam roofing. Even though the first standing seam roofs utilized exposed fasteners in the 1930’s, by the 1960’s the concealed clip design had come on to the construction scene.
            Insulated structural panels are an alternate type of concealed-fastened roofing application. They are also called foam-core sandwich panels. A couple of layers of steel sheets with insulation “sandwiched “ between defines this roofing style.
            Steel roofing will traditionally come shipped with panels that are ribbed and with the seams generally specified to be located along the pitch. Bermuda roofing, however, is an exception as it runs horizontally rather than vertically. This roofing style allows its panels to be through-fastened to its supports by means of concealed clips. The finished product will resemble a clapboard look. The drawback to this type of seam expression is in its design weakness which is why it tends to be avoided in any appreciable snow load locations.
            There are various seam applications that are available to work with any selected steel roofing style. One of these is the lapped seam configuration. This is commonly used with through-fastened roofs and can be described as a simple and cost-efficient approach. This is a conventional corrugated expression of roofing panels that overlap, are then sealed, and finally fastened to roof purlins. The disadvantage is seen in the fasteners as they are visible and exposed to the elements. Still, though without a lot of sophistication, this application is very suitable for buildings that need to be more functional than aesthetically pleasing.
            A vertical-seam or standing-seam roof elevates the seams up to three inches above the flat panel portion that guides water run-off. An alternate form of construction snaps together the seams and they are sealed in between.
            A batten seam roof configuration had its origins when the seam needed to be handcrafted and wood battens were utilized. This seam style is still used with two sides of panels next to each other bent up and secured with a cap. Today’s batten seam does not utilize, for the most part, a wooden batten.
            A flat seam is not commonly used today. It is configured by bending the sides of two roofing sheets that are side-by-side and attaching them one to another at a 180 degree angle.
            For all of the steel roofing options available on the market today the choice of a standing-seam roof predominates the market with the other styles described in this article very far behind in popularity.

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October 24, 2006

Steel Roofing with Attachments and Seaming

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