Modular metal roof systems:
This article explains the selection, use, and properties of modular metal roof shingle systems, including granular-surfaced metal roof shingles and snap-together metal roof shingles. We include a photo guide to types of metal roof shingles including antique metal shingles.
This article series discusses best practices in the selection and installation of residential roofing. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) , by Steven Bliss, courtesy of Wiley & Sons.
More photos of metal shingle roofs are at Metal Shingle Roofs. Also see our metal roofing home page, METAL ROOFING and see CORRUGATED ROOFING and COPPER ROOFING, our roofing home page: ROOFING INSPECTION & REPAIR.
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The metal roof shingles at below-right found on a New York home are steel, coated with a granular material that from the ground can be mistaken for asphalt. Carson Dunlop Associates 's metal roof shingle sketch (below left) provides additional details about this roofing option.
[Click to enlarge any image]
Adapted/paraphrased with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) , chapter on BEST ROOFING PRACTICES:
Modular metal shingles comprise the fastest growing segment of the metal roofing industry. Using light-gauge steel, copper, or aluminum, panels are stamped to imitate slates, shakes, asphalt shingles, or tiles. Some have aggregate stone finishes that closely resemble asphalt shingles. Most carry warranties from 20 to 30 years against fading and from 50-year to “lifetime” warranties against cracking or delamination of the shingle itself.
Modular shingles carry a Class A or B fire rating, depending on the material and installation details, and are highly resistant to wind uplift and damage from hail. Installed prices range from two to three times the cost of premium asphalt shingles. Installers accustomed to asphalt shingles or tile should have little trouble adjusting to metal shingles.
Modular shingles are typically stamped from lightweight .0165-inch metal, which is thinner than other types of metal roofing but stiffened by the textured patterns. Typical rectangular panel sizes range from 24 to 48 inches long by 12 to 16 inches wide, but they also include tile and diamond shapes and other specialty patterns.
The roof shown in our photo (left) was installed in Molde, Norway, an area of challenging winter weather.
Here is another Molde, Norway modular shingle metal roof showing a different METAL SHINGLE ROOF PATTERN [Image File]
Weights for modular metal shingle roofs range from 40 pounds per square for aluminum shingles to 140 pounds per square for steel shingles with a heavy stone aggregate.
The lightweight patterns are well suited to re roofing where weight is a concern. Most panels can be walked on, if done with care, but areas with heavy foot traffic should be reinforced with foam backers provided by the manufacturer.
Modular shingles are either nailed directly to the wood deck or attached to 2x2-inch battens installed at the exposed panel width, usually about 15 inches. Installation on battens allows more deeply etched patterns, such as simulated tiles. Either type can be installed with pneumatic nailers.
Our photograph at left illustrates a variegated colour modular metal shingle roof installed on a home in Christchurch, New Zealand. Metal roofs are the most common roof covering on residential buildings in Christchurch.
In earthquake prone areas such as Christchurch, metal roofing movement noise may be heard as a roaring freight train sound indicating the approach of a shock wave, perhaps giving an extra minute's notice of earthquake warning.
See EARTHQUAKE DAMAGE PHOTOS CA 1994
Underlayment for modular or "snap together" metal shingle roofs is minimum No. 30 asphalt felt held with plastic caps to avoid contact between incompatible metals.
Many manufacturers recommend proprietary laminated underlayments, such as VersaShield (Elk Premium Building Products, Inc.), which are tougher and less slippery than felt and provide better fire ratings. Aluminum shingles require fire-resistant underlayments to achieve an A or B fire rating.
Direct to deck Modular Metal Roof Shingle Method: Shingle panels installed directly to the deck are attached with concealed nails, either through clips or a nailing flange along the top, and have interlocking edges along all four sides (Figure 2-43 shown at left).
As they are installed, each panel locks to the panel below and to the left.
Modular Metal Roof Shingle Over battens: Modular panels designed for installation on battens have a nailing flange along the bottom of each shingle panel with nails going horizontally into the batten (Figure 2-44).
Roof battens are useful for modular metal roof shingle retrofits where the surface is irregular. Also, the air space boosts energy savings, especially when using shingles with solar-reflective surfaces.
Both systems begin with the installation of a drip edge and gable trim designed for the specific system.
Working from left to right, the first shingle panel hooks into the drip edge, which also serves as a starter strip.
Successive courses for modular metal shingles are staggered as specified by the manufacturer.
As we discuss at METAL ROOFING, the rusted metal shingles on the church roof (Clintondale, NY) shown in our photo (left) demonstrate more about the history of how metal roofing was used in the U.S. Here the original wood shingle roof was re-roofed using metal shingles, probably before 1900.
In general, most modular shingles can be installed over existing asphalt shingles [or wood or some other surfaces] if they are in good condition without excessive curling and deformation.
Metal modular roof shingles that are designed to go over battens (see above) have more flexibility, since the battens can be shimmed to create a level surface.
[Click to enlarge any image]
Manufacturers provide standard flashings similar to those for standing-seam products.
Eaves and rake flashings typically have concealed fasteners and lock the shingles in place.
Ridge and headwall flashings often require exposed fasteners.
Depending on the shingle profile, sidewall, chimney, and skylight flashings are either pan or step flashings.
Typical flashing and sealing details for metal modular roof shingles are shown at above left in Figure 2-45.
- - Adapted with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) .
As we discuss at METAL ROOFING, here are photographs of other modular metal roof shingle systems.
The antique embossed metal shingles (below) are found on the Justin Morrill Smith historic homestead, Vermont.
Quoting Grapefine Design Guidelines:
Metal roofing in America is principally a 19th-century phenomenon. Before then the only metals commonly used were lead and copper.
Tin-plate iron, commonly called "tin roofing," was used extensively in Canada in the 18th century, but was not commonly used in the United States until rolling mills were established in this country. The low cost, light weight, low maintenance and ease of shipping of tin plate made it a common roofing material.
Embossed tin shingles, whose Grapevine Design Guidelines – Roof Design Guidelines 4.9 - 2 surfaces created interesting patterns, were popular throughout the country in the late 19th century. Tin roofs were often kept well-painted in red or green to imitate the green patina of copper. Unfortunately, few of these roofs remain intact today.
Similar snap-together metal roof shingles made of copper are discussed
at COPPER ROOFING.
Flat metal shingles with interlocking edges were produced in both steel and copper, then soldered when in place. Usually we find these installed on flat or low-slope roofs such as at dormer insets on homes constructed in the U.S. before 1920.
Carson Dunlop Associates's standing seam metal roof sketch (below) includes a sketch of soldering used to connect flat metal roofing panels.
Watch out: large expanses of metal roofing with soldered connections may flex and break open the soldered joints due to thermal movement.
- - Adapted with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) .
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