Metal Roofing and Panel Systems

Metal roofing and panel systems are proven technologies that keep evolving over time in response to technology, codes, standards, and industry demand. Metal roofing systems are low maintenance, durable, and able to resist wind, fire, hail, and UV rays. Metal roofs are available in colors compatible with cool roofs. A cool roof refers to an outer layer or exterior surface of a roof that has high solar reflectance and reduces heat gain into a building.

Insulated metal panels are a form of continuous insulation, with rigid urethane foam sandwiched between two sheets of coated metal. IMPs serve as walls, ceilings, and roofs for commercial and industrial buildings, in new and retrofit construction. Suitable applications include schools, hospitals, religious, correctional, manufacturing and maintenance facilities, office buildings, aircraft hangars, distribution warehouses, and mechanical penthouses.

IMP systems provide many of the same benefits found with other metal wall and roof systems, plus some unique benefits. IMPs are composite, factory-fabricated units that attach directly to the supporting structure. The panels are factory-insulated, single-element panels with factory-applied coatings. They are lightweight, easy to install, with a one-piece construction process for faster building completion, all year round in any kind of weather, resulting in reduced construction and interim financing costs. There is reduced risk to system integrity since IMPs have few field-assembled components with no multiple installation steps.

INSULATED METAL WALL PANELS Pacific Plaza Tacoma, Washington LEED Platinum Architect: BLRB Architects The Pacific Plaza building was a four-story, crumbling parking garage. The $35-million renovation features two new floors of commercial space and a green roof. More than 26,000 square feet of IMPs clad the renovated office building and parking structure, for a monolithic, polished look. Panels finished in weathered zinc were installed horizontally. IMPs interface with a cement composite façade system cladding the exterior walls on the parking structure.

Photo courtesy of Metl-Span

 

Solar Power Arrays On Metal Roofs

According to the National Renewable Energy Laboratory, more energy from the sun falls on the earth in one hour than is used in one year. Solar cells, or photovoltaic (PV) cells, convert sunlight directly into electricity. Single solar cells combine to create a solar module. Solar modules combine to create a solar array, which is the PV system used to generate power.

Solar arrays are an ecological resource with a low carbon footprint that harnesses the sun's renewable energy. They will produce 85 percent of rated energy production 20 years after installation. Available in a variety of technologies including modules of polycrystalline and thin film, arrays are reliable, producing energy anywhere the sun shines at a fixed and known cost that won't fluctuate as fuel costs and utility rates escalate.

Photovoltaic Systems

Combining metal roofing with PV systems provides owners with several benefits. Solar modules can be installed on a metal roofing system with no penetrations through the roof, allowing the metal roofing warranty to remain intact. PV system efficiency typically improves with cool metal roof installations, by increasing the energy output of the solar modules.

Nearly 80 percent of PV installations occur on existing construction. The service life of a metal roofing system is compatible with that of a solar array. PV systems typically last at least 25 years. Rather than install a roofing system that will only last 15-20 years, requiring costly downtime, removal and reinstallation of the solar array during replacement of the roofing, choosing a metal roof that will last 40 years or more will allow the solar array to stay in place during its service life. This results in a savings on labor to remove and reinstall the array, savings on roof replacement, and avoids interruption of electrical generation and potential roof leaks.

Solar Array Installation

Before installing a solar array on any roof, a registered professional engineer should be consulted to determine if the roof can support additional loads. The best direction for the solar array to face is south, though roof areas facing east or west can also be used.

Usually, about 75 percent of a roof area can be utilized for the solar array, unless there are obstacles on the roof, such as skylights or rooftop equipment. Shading of the solar array should also be investigated. Solar modules cannot be installed to the roof edge. Adequate distance must be left at the roof edges for roof access.

Standing Seam Metal Roof Systems

A standing seam refers to the side joints of roof panels that are arranged in a vertical position above the roof line. A standing seam roof (SSR) system is one in which the side laps between the roof panels are arranged in a vertical position above the roof line. The roof panel system is secured to the roof substructure by means of concealed clips attached with screws to the substructure, except that through fasteners may be used at limited locations, such as ends of panels and at roof penetrations. Standing seam metal roof systems typically use concealed fastened systems, to hold panels firmly in place and accommodate thermal movement.

Standing seam metal roof systems are durable and weathertight. Vertical leg and trapezoidal are two popular types of structural standing seam metal roof systems. Vertical leg structural standing seam metal roof systems maintain UL uplift ratings, assuring reliable performance, while providing flexibility for design challenges.

Trapezoidal structural standing seam metal roof systems are available in snap-together and field-seamed systems, which are designed for strength, durability and weatherability. The standing seams are 3 inches above the lowest part of the panel, well above the water level as it flows off the roof. The rake/gable at both ends of each roof system finish with a 3-inch-high standing seam, avoiding the necessity of finishing in the low, flat part of the panel where the greatest possibilities for leaks occur in many other systems.

SSR panels can be installed before or after the exterior walls are in place. All trim is attached after the roof is installed. With a recommended minimum slope of ¼:12, these standing seam metal roof systems can be used on all types of construction, including metal, masonry or wood, for new construction or retrofit.

Ratings

Some manufactured standing seam metal roof systems carry the UL Fire Resistance and Wind Uplift (UL 90) ratings covering various roof designs. Testing certifications should be verified for each specification and building code.

Special clips allow for thermal roof expansion and contraction during extreme temperatures. Trim should be weathertight, to secure against wind and rain. Factory-applied sealant in the panel sidelap ensures a weathertight lap.

As with all standing seam metal roof systems, sound attenuation (such as blanket insulation) is required between the panel and the substructure to prevent “roof rumble” during windy conditions. Some composite roof systems may require additional acoustical consideration to ensure that thermal vibration noises are isolated from the building's interior.

Insulated Metal Panels

Buildings are more comfortable and energy efficient with the right insulation. In the winter, heat flows out; in the summer, heat flows in. A properly insulated structure reduces the heat flow, so less energy is used for heating in the winter and cooling in the summer, resulting in cost savings. To create a wall with high thermal performance, air leakage, infiltration, thermal bridging, insulation, condensation, and fire protection must be controlled.

Core Insulation Components
Insulated metal panels consist of rigid urethane foam sandwiched between two sheets of coated metal, molded in different styles and sizes. Steel panel facings create a vapor barrier, and the skins are resistant to abuse. Polyurethane and polyisocyanurate have similar insulating properties for compressive, tensile and shear strength, and foam density. Steel panel facings contain more than 30 percent recycled content, while foam cores contain 7 percent pre-consumer recycled content. Panels can be disassembled, moved, and reused.