Anatomy of a Steel Building: Roof and Wall Sheeting
There are several types of panels that can be used as exterior/interior walls and roof. Almost every kind of panels utilize exposed fasteners, which are used to attach panels to a surface, structure or each other. For the sake of time and to not bore you to death, we will focus on the most commonly used exposed fastener panels, PBR (Purlin Bearing Rib) and R panels, paint and protective coatings and some best practices. If you haven’t caught up with the rest of the blogs in this series, Anatomy of a Steel Building, click here.
Note: Standing seam panels are durable and maintenance-free roofing systems which are installed using a clip and interlock design. Their main purpose is to conceal the fasteners and prevent water from leaking into your steel building.
PBR and R Panel:
PBR and R metal panels are the most commonly used for a wide variety of architectural, agricultural, commercial and industrial prefabricated metal buildings. PBR and R panels are low-maintenance and durable. PBR panels adds extra protection against the elements by including a purlin bearing leg, which overlaps between panels sealing out moisture and wind. See detail below.
- Coverage Width – 36″
- Minimum Slope – 1/2:12
- Gauge – standard 26 and 24, 22 options
- Exposed Fastening System
- Rib Spacing – 12″ on center
- Rib Height – 1-1/4″
Paint and Protective Coatings.
For both protection and decoration, nearly all prefab steel structure companies offer some type of finish for metal roofing and wall sheeting. Here are a few of the most common painted and protective coating systems used for roofing and wall sheeting.
Most roof and wall sheeting are constructed from commercial grade steel. The steel panels are then coated with Galvalume. (consisting of 55% aluminum, 43.4% zinc and 1.6% silicon over the base metal) This coating has superior corrosion resistance, which can more than double the life span of a metal panel
Kynar resin or PVDF (polyvinylidene fluoride), offers long-life protection for aluminum, galvanized and anodized steel. Kynar paint systems can withstand harsh ultra-violet rays of the sun and the degrading effects of weather extremes from the equator to the arctic. As will most finishes, Kynar paint can be washed with conventional detergents and solvents. Additionally, panels with Kynar usually come with a longer limited warranty on fading, chalking, cracking, and airborne pollutants.
Silicon Polyester is applied to steel sheeting and then baked on for durability and longevity. There are typically more color options with Silicon Polyester than with Kynar, however Silicon Polyester systems usually offer a 25-year finish warranty. Check with your steel structure provider or manufacture for details.
If you do not plan to erect shortly after you receive your metal building, ensure panels are stored properly to prevent moisture damage. Elevate one end of your steel sheeting bundle to allow moisture to drain. You can use a 2”x4” or wood blocking to elevate the one end (Make sure to separate wall and roof sheeting). Loosely cover with waterproof tarp to allow proper air circulation and inspect daily and dry if necessary. Additionally, make sure that the foundation is square, level, and correct to the out-to-out steel line dimensions. Lastly, prevailing wind, main traffic area, etc. should be taken into consideration when sheeting roof and walls.
There you have it. We hope you enjoyed our series on the Anatomy of a Steel Building. And as promised, gift from us to you. We hope you’ll find it helpful.
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