Metal Buildings Guide — Encyclopedia

📘 Metal Buildings Guide Encyclopedia

You’re reading the straight-shot, no-fluff buyer’s encyclopedia for steel buildings. Use this like a checklist and a map: pick the right frame, set the right loads, detail openings correctly, choose panels and insulation that keep water out and energy in, design the slab and anchors to carry the building, plan a safe erection, navigate permits and inspections, lay out interiors and mezzanines, and finally—buy smart with apples-to-apples quotes.

Section 1: Structural Steel & Finishes

Everything starts with your frame. Here's what you need to know.

Cold-Formed Steel

What it is:
Light-gauge steel shaped at room temperature into C, Z, U and angles for full building frames and secondary members. Precision-punched, bolt-together, ships compact.

Why it matters:
Fast installs with smaller crews and equipment. Ideal for shops, garages, small commercial, barndos. Clear spans commonly up to ~60' (more with engineering).

MBG’s Take:
Under ~5–6k SF and no cranes? Cold-formed is a surgical, efficient choice.

Ask your supplier:
• Which gauges (14/12)?  • Pre-punched?  • Flush vs bypass girts?  • Max clear span?

Red Iron (Rigid Frame Steel)

What it is:
Hot-rolled W-shapes welded into tapered rafters/columns with reinforced haunches.

Why it matters:
Spans from 30' to 200'+, handles cranes, tall walls, high wind/snow, mezzanines.

MBG’s Take:
Big, tall, heavy-duty? You’re in red-iron country.

Ask your supplier:
• Clear vs modular span?  • Rafter/column sizes?  • Anchor bolts by who?  • Haunch depth/flange width?

Hot-Dip Galvanized vs Red-Oxide Primer

What it is:
HDG is zinc-coated inside/out for corrosion resistance; red-oxide is transport primer.

Why it matters:
Coastal, ag, wastewater: go HDG. Dry inland + quick erect: primer may suffice (top-coat soon).

MBG’s Take:
Salt air eats primer. Specify galvanizing for base angles, girts, purlins, clips.

Ask your supplier:
• HDG or electro-galv?  • Coating weight (G90+)?  • Which members are galvanized?

Z-Purlins / C-Purlins & Girts

What they are:
Roof (purlins) and wall (girts) secondaries. Z overlaps for continuity; C used in CFS, headers, jambs.

Why they matter:
Spacing, depth, gauge, and bracing control deflection, screw pull-out, insulation space.

MBG’s Take:
Flush girts = cleaner lines + better insulation; bypass = speed but added wall depth.

Ask your supplier:
• Spacing/gauge/depth?  • Bridging/straps?  • Punched patterns?

Clear Span vs Modular Span, Lean-To, Haunch, Base Conditions

Key points:
• Clear span = open floor; modular = interior cols for steel savings.
• Lean-to adds low-cost covered area now, enclosure later.
• Haunch depth governs clearance and stiffness.
• Base angles/trim, closures, sealant = leak-free start.

Section 2: Building Loads, Deflection & Frame Behavior

Dead Loads
Weight of permanent materials (frames, panels, insulation). Baseline for design.

Live Loads
Temporary roof/floor usage. Plan for maintenance, solar, catwalks.

Collateral Loads
All hung items: lights, HVAC, sprinklers, fans, signage, ceilings.

Snow Loads
Zip-specific. Consider slope, thermal, exposure. Don’t guess.

Wind Loads
Pressures and uplift on roof/walls/doors/corners. Exposure category drives it.

Seismic Loads
Depends on site class, SDC, risk category. Check drift and anchorage.

Frame Deflection
Limits like L/240 (walls) / L/180–L/240 (roof) protect finishes and laps.

Purlin/Girt Deflection
Spacing + gauge + bridging. Avoid ponding and bowing.

Expandable Frames & Portal Frames
Plan future bays now; portal frames when X-bracing won’t fit.

Ask your supplier (loads):
• Wind speed & Exposure?  • Ground snow (Pg)?  • Roof live load?  • Collateral PSF?  • SDC & drift limits?

Section 3: Framed Openings

Walk Doors
Use jamb/ header kits sized to panel rib, include sub-framing and trim. Prehung steel doors with thresholds, sweeps, and weatherstripping.

Overhead / Roll-Up Doors
Wind-rated with guides, headplates, hood. Add framed opening with lateral jamb bracing or portal frame if clustered.

Windows
Self-flashing or framed units; match panel profile; use closures and butyl.

Storefront/Glass Walls
Tube steel jambs/headers tied to main frame; check drift limits.

Rooftop Penetrations
Curb-mounted with boots/flashings; reinforce purlins around large curbs.

Ask your supplier:
• Opening sizes/locations on plan?  • Jamb/header steel included?  • Trim/closures type?  • Door wind rating?  • Required bracing?

Section 4: Panels, Trim & Weather-Tightness

Panel Types
• Roof: PBR, standing seam (floating), trapezoidal.  
• Wall: PBR, reverse-PBR, architectural rib, insulated metal panels (IMP).

Gauges & Substrates
26 ga standard; 24 ga premium. Galvalume AZ50/55 common; specify SMP or PVDF paint.

Fasteners & Patterns
Use long-life fasteners with sealing washers; honor manufacturer layout at edges/corners.

Trim & Flashings
Eave/rake/base/gable trims; side/endlap details; foam closures; butyl and tape sealants.

Gutters & Downspouts
Sized to roof area and local rain intensity. Add snow guards if applicable.

Skylights & Translucent Panels
Match panel profile; reinforce purlins; consider UV and hail ratings.

Ask your supplier:
• Panel gauge/substrate/paint system?  • Fastener type/coating?  • Weathertight warranty?  • Trim pieces included list?

Section 5: Insulation, Condensation & Ventilation

Systems
• Vinyl-faced fiberglass (WMP-VR, WMP-50).  
• Liner system (sub-girts + interior panels).  
• IMPs (foam core, highest performance).  
• Reflective foils (supplemental).

Thermal Performance
Mind compression over purlins; thermal blocks under panels improve R.

Condensation Control
Vapor retarders sealed at laps/penetrations. Drip-stop membranes as backup.

Ventilation
Ridge vents, eave soffit intake, wall louvers, mechanical exhaust.

Ask your supplier:
• Insulation thickness & facings?  • Continuous vs over-purlin R?  • Vapor retarder location?  • Vent strategy (net free area)?

Section 6: Foundations, Anchor Bolts & Slabs

Geotech & Design
Soil report drives footing sizes. Coordinate with local PE and building supplier reactions.

Anchor Bolts
Templates with hold-downs; J-bolts or epoxy-set where allowed; verify projection and pattern.

Slab Details
Thickened edge vs piers; rebar schedule; vapor barrier; saw-cut joints; door recesses.

Column Base Plates & Grout
Leveling nuts or shim packs; non-shrink grout after plumb/torque.

Loads Into Concrete
Uplift and shear from wind/seismic; check edge distances and embedment.

Ask your supplier/engineer:
• Reactions and fixity?  • Bolt size/grade/pattern?  • Edge distances?  • Slab pour sequence?

Section 7: Installation, Safety & Erection Planning

Pre-Erect
Verify anchor layouts, unload sequence, part inventory, crane access, staging.

Plumb & Square
Set endwalls first, brace, then run bays. Torque specs on all bolts.

Bracing
Permanent X-bracing, strap bracing, portal frames as detailed; temporary bracing during set.

Panel Install
Square first sheet, maintain module, stitch laps to spec, seal all sidelaps/endlaps.

Safety
Fall protection, lift plans, weather limits, hot work permits.

Close-Out
Final torque, punch list, touch-up paint, as-built photos.

Section 8: Permits, Codes & Inspections

Jurisdiction
Confirm adopting code (IBC year), local amendments, design wind/snow/seismic, risk category.

Submittals
PE-stamped calculations, anchor plan, reactions, shop drawings, panel sheets, weathertight details.

Inspections
Footings, anchor bolts before pour, framing, sheathing, final.

Zoning & Site
Setbacks, height, lot coverage, drainage, driveway, utilities.

Ask the building department:
• Required code edition?  • Wind speed/Exposure?  • Snow load?  • SDC/site class?  • Special inspections?

Section 9: Mezzanines, Interiors & Utilities

Mezzanines
Live load rating (typically 125 PSF warehouses, 60–100 PSF offices), stair/guard compliance, column loads to slab, vibration control.

Liners & Finish-Out
Interior liner panels or drywall; fire separation if needed; acoustic control.

HVAC & Electrical
Hanging loads (unit heaters, ducts, cable trays). Provide inserts/frames and collateral load in design.

Plumbing
Sleeves through slab, trench drains, bathrooms, frost depth.

Fire Protection
Sprinklers, fire flow, hydrant distance; coordinate with roof structure and water supply.

Section 10: Metal Building Quotes — What to Look For (Apples-to-Apples)

Scope & Inclusions (Building Supply)
• Frame type (clear/modular), bay spacing, eave height, roof pitch.  
• Design criteria: Code edition, wind speed & Exposure, ground snow, SDC, risk category.  
• Secondary steel: purlin/girt gauge, spacing, bridging.  
• Panels: profile, gauge, substrate (Galvalume), paint (SMP/PVDF), fasteners.  
• Openings: framed openings for all doors/windows, jamb/header steel, trim.  
• Trim & flashings: complete list; closures; sealants; gutters/downspouts.  
• Insulation: type, thickness, facing, R-value method (nominal vs effective).  
• Drawings: PE-stamped calcs and plans included? State(s)?  
• Warranty: paint, perforation, weathertight (if offered).

Exclusions (Common—Confirm in Writing)
• Foundation design/permit fees/anchor bolts (if by others).  
• Erection labor, equipment, cranes, safety, temporary bracing.  
• Interior build-out, electrical, plumbing, HVAC, fire sprinkler.  
• Sales tax, unloading, off-loading equipment, storage.  
• Engineering outside listed states or special inspections.

Logistics & Cost Adjusters
• Freight (included or add?), fuel surcharges, delivery windows, off-loading responsibility.  
• Lead time (frames, panels, doors) and phasing options.  
• Price hold duration and escalation clause.

Quality/Spec Checks
• Haunch depth/flange widths; maximum bay spacing; expandable endwall.  
• Door wind ratings; portal frames if openings cluster; collateral load PSF included.  
• Fastener coating and panel side/endlap details matched to wind zone.  
• Insulation compression details, thermal blocks, ridge/eave venting.

Payment & Terms
• Deposit %, progress draws, final payment timing.  
• Change order policy, restocking, cancellation fees.  
• Dispute venue and governing law.

Red Flags
• No design criteria listed.  
• “Comparable” quotes using different gauges/spacings.  
• Missing freight or unrealistic lead time.  
• Refusal to provide stamped calcs where required.

Buyer’s Checklist (Copy/Paste)
□ Code, wind, snow, seismic, risk category match  
□ Frame type/bay spacing/eave height/pitch match  
□ Purlin/girt gauge & spacing match  
□ Panel profile/gauge/substrate/paint match  
□ All openings + jamb/header steel included  
□ Trim/closures/sealants/gutters included  
□ Insulation type/thickness/facing/R method match  
□ PE stamps, state(s), warranty terms listed  
□ Freight/lead time/payment terms clear  
□ Taxes/fees and exclusions acknowledged

MBG’s Take:
Force every supplier onto the same spec sheet. If one price is far lower, something is missing—usually steel, logistics, or engineering. Buy the building you actually need, not the one that looks cheaper on paper.

— End of Encyclopedia —