History

Metal roofs date back to 970 BC to the Temple in Jerusalem, where some accounts report a roof to be made of copper. Other notable metal systems included Notre Dame in Paris and Thomas Jefferson's Monticello in Virginia.

Construction

A standing seam metal roof is constructed of numerous panels that are placed over an underlayment or over the existing roof. The panels interlock vertically from the roof ridge to the eave. Water is prevented from seeping into the structure by overlaying the higher section on the lower sections as you move down the slope of the roof.

Exposed Attachment

One system of attaching the panels to the underlayment is the exposed attachment. The panels are screwed to the sheathing using protective washers to help prevent water from seeping in around the screws. The screws can be seen, and though not as aesthetically pleasing as alternative attachment methods, it works with the system to achieve the goals at less cost.

Hidden Fasteners

Hidden fasteners are the most reliable and aesthetic method to protect against water seepage in a metal roof system. Each fastener is attached in such a way that the panel above it covers the fasteners and clips used to connect the roof to the frame of the structure.

The Roof System

Metal is more durable than other roofing materials such as asphalt shingles. It is less likely to be raised by the winds when fastened correctly because of the larger panels used in construction. When used in cold, snowy climates, the sun heats up the metal, preventing snow from building up and threatening the structure with overload and collapse.

Choice of Metal

Copper, steel, stainless steel, aluminum or an alloy can be used. Each functions differently. Because steel rusts, manufacturers coat the material with a baked-on enamel paint. Lighter materials put less load on the structure, while heavier materials tend to last longer. No matter which material is chosen, metal roofs are durable, and they protect against wind damage and snow load collapse.

Source:

Bob Villa: Standing-Seam Metal Roof Basics

Home Tips: Metal Roofing Materials

More Information:

Metal Roofing Association