Metal Building Systems
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
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to Rev 2
in Metal Building Systems.
---
title: Metal Building Systems
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## The manufacturer's structural design shall be performed under the direct supervision of a Professional Engineer licensed in the jurisdiction of the project, and all structural calculations and drawings shall bear that engineer's seal.
−## The division of design responsibility shall be documented before fabrication begins. {note}
+## The division of design responsibility shall be documented before fabrication begins.
−### 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. {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.
## Anchor bolt design responsibility shall be split as follows: the manufacturer designs bolt diameter, grade, and pattern and furnishes setting templates; the Engineer of Record designs embedment depth and concrete breakout per ACI 318-19 Chapter 17.
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## End-wall type shall be specified at the time of purchase to preserve any planned future expansion.
−## Future expansion must be designed in, not added later. {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. {note}
−
```datasheet
label: Endwall framing
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```
−# Materials {toc}
+## Future expansion must be designed in, not added later.
−## Primary frame web and flange plates shall be ASTM A572 Grade 50 (Fy = 50 ksi) minimum, except that miscellaneous plates, base plates, and stiffeners may be ASTM A36.
+### 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. {note}
−## Primary frame steel grade reflects industry practice. {note}
+# Primary frame web and flange plates shall be ASTM A572 Grade 50 (Fy = 50 ksi) minimum, except that miscellaneous plates, base plates, and stiffeners may be ASTM A36.
−### 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. {note}
+# Primary frame steel grade reflects industry practice. {note}
−## Cold-formed secondary members - purlins, girts, and eave struts - shall be ASTM A1011 Grade 55 (Fy = 55 ksi) minimum and shall be galvanized to ASTM A653 G90 coating minimum.
+## 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. {note}
−## Secondary members are galvanized because they are thin and concealed. {note}
+# Cold-formed secondary members - purlins, girts, and eave struts - shall be ASTM A1011 Grade 55 (Fy = 55 ksi) minimum and shall be galvanized to ASTM A653 G90 coating minimum.
−### 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. {note}
+# Secondary members are galvanized because they are thin and concealed. {note}
−## Roof and wall panels shall be 55% aluminum-zinc alloy-coated (Galvalume) steel sheet conforming to ASTM A792, AZ50 coating designation minimum.
+## 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. {note}
−## The panel substrate, gauge, and finish shall be as follows.
+# Roof and wall panels shall be 55% aluminum-zinc alloy-coated (Galvalume) steel sheet conforming to ASTM A792, AZ50 coating designation minimum.
+# The panel substrate, gauge, and finish shall be as follows.
+
```datasheet
label: Roof panel substrate
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```
−## The exterior finish coat warranty period drives the resin selection. {note}
+# The exterior finish coat warranty period drives the resin selection. {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. {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. {note}
−## Anchor bolts shall be ASTM F1554 Grade 36 (Fy = 36 ksi) by default, and ASTM F1554 Grade 55 where uplift or shear reactions require the higher grade.
+# Anchor bolts shall be ASTM F1554 Grade 36 (Fy = 36 ksi) by default, and ASTM F1554 Grade 55 where uplift or shear reactions require the higher grade.
```datasheet
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```
−## Secondary-member bolts (purlin-to-frame, girt-to-column) shall be ASTM A307 minimum.
+# Secondary-member bolts (purlin-to-frame, girt-to-column) shall be ASTM A307 minimum.
−## Primary frame splice and end-plate moment connections shall use high-strength bolts conforming to ASTM F3125 Grade A325; Grade A490 shall be used only where the design specifically requires it.
+# Primary frame splice and end-plate moment connections shall use high-strength bolts conforming to ASTM F3125 Grade A325; Grade A490 shall be used only where the design specifically requires it.
# Roof and Wall Systems {toc}
## The roof panel system type shall be selected for the project's slope, thermal-movement, and warranty requirements.
−## Standing-seam and through-fastened systems trade economy against performance. {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. {note}
−
```datasheet
label: Roof panel attachment system
…6 unchanged lines
```
+## Standing-seam and through-fastened systems trade economy against performance. {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. {note}
+
## The wall system shall be one of the manufacturer's standard configurations as scheduled.
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## Primary frame members shall receive the shop primer system scheduled below, applied over surfaces prepared in accordance with the primer manufacturer's required surface preparation.
−## The default shop primer is a holding primer, not a finish. {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. {note}
−
```datasheet
label: Primary frame coating system
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```
+## The default shop primer is a holding primer, not a finish. {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. {note}
+
## Where a corrosive or high-humidity service environment is identified, the coating system, the secondary-member coating, and the panel substrate shall be upgraded as a coordinated set rather than individually.
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## Anchor bolt setting tolerance is where the foundation and the frame must agree. {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. {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.
## Member deflection limits shall be as scheduled and shall be verified by the manufacturer's design.
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## Restraining a floating roof defeats its purpose. {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. {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.
## Field cutting, drilling, or welding of primary frame members shall not be performed without the manufacturer's prior written approval.
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## Weathertightness warranties differ sharply in what they actually cover. {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. {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.
```datasheet
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- Galvanizing repair compound
```