NOTE A metal building system is a delegated-design product, not a conventional structure. (1.2)

NOTE The structural frame is engineered and sealed by the manufacturer's licensed Professional Engineer using inputs (loads, geometry, dimensions) furnished by the contract documents, then fabricated as a coordinated kit of plate-built primary members and cold-formed secondary members. The single defining characteristic of this Section is that one manufacturer carries the structural design responsibility for the building system. Where the project instead uses individually engineered wide-flange members detailed by the Engineer of Record, that work belongs to Structural Steel Framing, not here. (1.2.1)

NOTE Several adjacent scopes are deliberately excluded and are governed by their own Sections. (1.5)

NOTE Cast-in-place foundations, grade beams, piers, and the embedment design of anchor bolts are Engineer-of-Record scope under Cast In Place Concrete and Concrete Reinforcement; this Section addresses only the bolt diameter, grade, pattern, templates, and reaction loads the manufacturer furnishes to the EOR. (1.5.1)

NOTE Overhead doors and their tracks are not in the base MBS package and are governed by Overhead Coiling Doors and Sectional Overhead Doors; the MBS scope is limited to framing the rough openings and providing jamb and header support. (1.5.2)

NOTE Applied fire-resistive coatings and spray fireproofing of primary members are governed by Fireproofing. (1.5.3)

NOTE Field-applied joint sealants and the continuous air barrier, where required beyond the panel manufacturer's standard closures, are governed by Joint Sealants and Air Barriers. (1.5.4)

NOTE Ambiguous design loads are the single most common source of redesign and field RFIs on metal buildings. (3.2)

NOTE When ground snow load, basic wind speed, exposure category, risk category, seismic design category, or collateral loads are left unstated, the manufacturer will adopt code-minimum defaults that frequently undersize the frame for actual project conditions. Every load parameter below is to be a positive value carried on the contract documents, not a value the manufacturer infers. (3.2.1)

NOTE Collateral loads added after frame purchase are expensive to accommodate. (3.4)

NOTE Suspended mechanical equipment, sprinkler mains, interior ceilings and liner panels, and process loads are routinely added after the frame is purchased and fabricated. Carrying an explicit collateral allowance from the outset avoids a frame redesign and the associated schedule and cost impact. (3.4.1)

NOTE The division of design responsibility shall be documented before fabrication begins. (3.7)

NOTE The manufacturer's engineer is responsible for the design of the building system: primary frames, secondary members, bracing, panels, and their connections to one another. The Engineer of Record reviews the manufacturer's submittals for conformance with the contract documents - loads, geometry, and the interface with EOR-designed elements such as foundations - but is not responsible for the manufacturer's internal member design. This division shall be stated in the contract so that no party assumes the EOR has independently re-engineered the frame. (3.7.1)

NOTE The anchor bolt responsibility split is a frequent gap in coordination. (3.9)

NOTE The manufacturer sizes the bolts to its computed reactions and provides a setting template, but the embedment into the foundation - the part that resists pullout and concrete breakout - is Engineer-of-Record scope under ACI 318-19 Chapter 17. The contract shall name the party responsible for each half of this design. (3.9.1)

NOTE Frame type follows directly from the interior clear-span requirement. (4.2)

NOTE A clear-span rigid frame carries the roof with no interior columns and is selected when the full building width must be column-free; spans to roughly 300 ft are available. A multi-span frame introduces interior columns on a 20 ft to 30 ft module and is more economical when the interior need not be fully open. A lean-to is a single-slope frame that bears against an existing wall or taller structure. A modular system repeats a standard bay so the building can be lengthened in fixed increments. The tapered-column, tapered-rafter rigid frame - in which the web plate deepens toward the points of highest moment - is the most common and most economical form for warehouse and industrial work. (4.2.1)

NOTE Future expansion must be designed in, not added later. (4.6)

NOTE Bay spacing and column lines established at purchase are very difficult to change afterward. Where future expansion bays are anticipated, an expandable (rigid-frame) end wall is specified at purchase instead of a flush (post-and-beam) end wall; converting a flush end wall to an expandable frame later requires replacing the entire end frame. (4.6.1)

NOTE Primary frame steel grade reflects industry practice. (5.2)

NOTE Built-up primary members are fabricated from plate, and ASTM A572 Grade 50 is the industry-standard base metal for webs and flanges because it balances strength against weldability and cost. Grade 55 is used where a manufacturer's standard line calls for it. ASTM A36 remains acceptable for secondary plate items where the higher yield is not needed. (5.2.1)

NOTE Secondary members are galvanized because they are thin and concealed. (5.4)

NOTE Purlins and girts are light-gauge cold-formed sections that cannot tolerate the section loss that uncoated steel would suffer in a condensing roof or wall cavity, and they are largely inaccessible for re-coating once the panels are on. A G90 hot-dip galvanized coating is the minimum first line of corrosion defense for these members. (5.4.1)

NOTE The exterior finish coat warranty period drives the resin selection. (5.7)

NOTE A 70% PVDF fluoropolymer coating supports a film-integrity and color-retention warranty on the order of 30 to 40 years and is the default where appearance and longevity matter. A silicone-modified polyester coating costs less but carries a shorter warranty and chalks and fades sooner; it is reserved for economy applications. Bare Galvalume is used on concealed or utilitarian surfaces where no painted finish is required. (5.7.1)

NOTE Standing-seam and through-fastened systems trade economy against performance. (6.2)

NOTE A standing-seam roof conceals its fasteners in a raised seam and rides on clips that let the panel expand and contract with temperature; this floating attachment is what permits long panel runs, low slopes, and a weathertightness warranty. A through-fastened (exposed fastener) roof drives screws straight through the panel into the purlin - cheaper and faster, but every fastener is a penetration and a point of thermal stress and potential leakage, so it is reserved for utilitarian buildings and steeper slopes. (6.2.1)

NOTE Panel modules and openings rarely align by accident. (6.7)

NOTE Metal building panels come in fixed modular widths (commonly 12 in, 36 in, or 40 in), and door, window, and louver openings that ignore that module force cut panels, off-module trim, and unsightly reveals at the jambs. Aligning opening locations to the panel module during design avoids field improvisation and preserves the intended elevation. (6.7.1)

NOTE Effective R-value, not nominal batt R-value, is what the energy code grades. (7.2)

NOTE A simple faced batt draped over purlins or girts is compressed and short-circuited at every secondary member, so the assembly R-value is far below the batt's nominal rating - a nominal R-19 blanket can deliver an effective value in the low teens once the thermal bridging through the steel is counted. ASHRAE 90.1-2022 binds the assembly to an effective value (roughly R-30 effective for roofs and R-13 effective for walls across Climate Zones 3 to 8), so a thermal-block or engineered-spacer system that breaks the metal-to-metal bridge is required to comply. The submittal shall demonstrate the effective R-value, not just the material rating. (7.2.1)

NOTE Crane support is integral to the frame, not an afterthought. (8.2)

NOTE A crane imparts vertical, lateral, and longitudinal loads and a fatigue cycle that the primary frame must be designed for from the start. The crane service classification (CMAA Class A through F), the lifted capacity, the bridge span, and the rail elevation must all be stated so the manufacturer can size the runway beam, the column brackets, and the frame for the combined and repeated loading. (8.2.1)

NOTE The default shop primer is a holding primer, not a finish. (9.2)

NOTE A standard one-coat metal-building shop primer (SSPC-Paint 15 over an SSPC-SP3 power-tool-cleaned surface) protects the steel during shipping and erection but is not a long-term or architectural finish; interior frames in dry, heated buildings normally need nothing more. A more durable epoxy or hot-dip galvanized system is specified where the frame is exposed to weather, high humidity, corrosive process atmospheres, or will be left architecturally exposed. (9.2.1)

NOTE Plant accreditation substitutes for re-inspecting the factory. (11.2)

NOTE The IAS AC472 accreditation program audits a metal-building plant's engineering, materials control, and fabrication quality on an ongoing basis, which is why building officials accept AC472-accredited fabrication without a project-specific shop inspection regime. Requiring it gives the owner a verified baseline of fabrication quality. (11.2.1)

NOTE Erection by an unapproved crew puts the warranty at risk. (11.4)

NOTE Most manufacturers condition their structural and weathertightness warranties on erection by an authorized erector following the manufacturer's instructions, and will disclaim liability where an unapproved crew assembles the building. Naming the approval requirement in the contract protects both the warranty and the fit-up of a kit that depends on precise assembly. (11.4.1)

NOTE Anchor bolt setting tolerance is where the foundation and the frame must agree. (12.4)

NOTE Anchor bolt groups must be set within roughly ±1/8 in of the manufacturer's template - much tighter than the general tolerances a concrete contractor works to - because the base plate holes are punched to that template. When the bolts are set loose to ordinary concrete tolerance, the frame will not fit up, and the field cutting, reaming, or re-drilling needed to force it can void the structural warranty. The setting tolerance shall be called out to the foundation contractor and verified by survey before the frame ships. (12.4.1)

NOTE Temporary bracing is the erector's responsibility and the most common cause of erection collapse. (13.2)

NOTE A metal building frame is stable only once its permanent diagonal bracing, flange braces, and panels are in place; partway through erection it depends entirely on temporary guying and bracing. Removing temporary bracing before the permanent system is complete is a leading cause of erection-stage collapse, so the temporary bracing remains until the manufacturer's permanent lateral system is installed and connected. (13.2.1)

NOTE Restraining a floating roof defeats its purpose. (13.5)

NOTE A floating standing-seam roof is engineered to move; pinning it down at a curb, a pipe penetration, or an over-tight trim screw concentrates the thermal movement at the nearest unrestrained point and tears the seam or the clip there. Penetrations and trim shall accommodate the panel's designed movement rather than fix the panel in place. (13.5.1)

NOTE Bundled metal panels are vulnerable to water staining and erection damage. (14.2)

NOTE Galvalume and painted panels bundled tight at the factory will stain and corrode from the inside out if water wicks between them and cannot dry - the well-known wet-stack or water staining failure. Panels are stored sloped, blocked clear of the ground, and ventilated, and are not allowed to sit in standing water on site. Handling lifts panels rather than dragging them, to protect the finish and the cut edges. (14.2.1)

NOTE Weathertightness warranties differ sharply in what they actually cover. (15.3)

NOTE A material-only weathertightness warranty covers the panel material but leaves leak repair labor to the owner, while a single-source (no-dollar-limit) warranty covers diagnosis, materials, and labor up to the building's value and is typically conditioned on the manufacturer's own inspection of the completed roof. The warranty type shall be specified so the coverage matches the owner's expectation rather than being discovered after the first leak. (15.3.1)