Quick Answer
For a 1,500 sq ft single-story house with 9′ walls (≈ 540 sq ft of siding area per side), plan on roughly 6 squares of metal siding per side after 10% waste — about 24 panels in 3′-wide PBR/R-Panel or 32 panels in 16″ Board & Batten. Get exact panel, fastener, and trim counts using our siding calculator (select "Metal Siding").
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View Product (paid link)What Is Metal Siding?
Metal siding is roll-formed steel, aluminum, copper, or zinc panel cladding installed on exterior walls. Steel and aluminum dominate residential and light-commercial use; copper and zinc are premium architectural specifications. The two big advantages over vinyl and fiber cement are longevity — most metal substrates carry 25–40 year substrate warranties and 30-year paint finish warranties — and fire performance: metal is inherently noncombustible (UL 790 Class A), which matters in wildfire-prone zones.
The two big disadvantages are upfront cost (typically 30–50% more installed than vinyl) and denting. Aluminum lap siding in particular dents from hail and ladder impact; thicker steel gauges (24 ga and below) are far more resistant. Color matching after damage is also harder than vinyl because paint batches drift over decades.
Steel Gauge & Aluminum Thickness — How to Pick
Steel siding is specified by gauge (the lower the number, the thicker the steel). Aluminum is specified in decimal inches. The choice affects strength, dent resistance, oil canning, weight, and cost.
| Material | Spec | Weight | Best for |
|---|---|---|---|
| Steel | 22 ga | 1.30 lb/sq ft | Commercial, HVHZ, premium dent resistance |
| Steel | 24 ga | 1.00 lb/sq ft | Standing seam standard — flatter panels, less oil canning |
| Steel | 26 ga | 0.88 lb/sq ft | Residential default — balances strength & cost |
| Steel | 29 ga | 0.65 lb/sq ft | Agricultural / pole barn — lowest cost |
| Aluminum | 0.019″ | 0.30 lb/sq ft | Budget aluminum lap |
| Aluminum | 0.024″ | 0.40 lb/sq ft | Coastal residential standard |
| Aluminum | 0.032–0.040″ | 0.45–0.55 lb/sq ft | Architectural standing seam, coastal high-end |
Weights per ASTM A653 (galvanized steel) and A792 (Galvalume). Gauge tables apply only to steel — never specify aluminum, copper, or zinc by "gauge."
The 80% answer for residential: 26-gauge painted Galvalume steel is the default. Bump up to 24-gauge if you're installing standing seam or wide smooth panels where oil canning would be visible. Step up to 22-gauge in HVHZ regions or for commercial-grade dent resistance. Drop to 29-gauge only if you're explicitly trying to hit a budget on an agricultural-style structure.
Substrate Coatings: Galvanized vs. Galvalume
Before paint, steel siding is coated with either pure zinc (galvanized) or an aluminum-zinc alloy (Galvalume). The coating designation specifies coating weight per square foot, total both sides, per ASTM A653 (galvanized) or A792 (Galvalume).
| Coating | Composition | Weight (total) | Use |
|---|---|---|---|
| G60 | Pure zinc | 0.60 oz/sq ft | Light commercial / agricultural |
| G90 | Pure zinc | 0.90 oz/sq ft | Standard galvanized siding/roofing |
| AZ50 | 55% Al / 43.4% Zn / 1.6% Si | 0.50 oz/sq ft | Painted Galvalume — most common |
| AZ55 | Same as AZ50 | 0.55 oz/sq ft | Unpainted (bare) Galvalume |
| AZ60 | Same as AZ50 | 0.60 oz/sq ft | Coastal Galvalume (still excludes ≤1,500 ft from saltwater) |
Per Metal Construction Association research, Galvalume (AZ50/AZ55) lasts roughly 2–9× longer than galvanized of equal coating weight in atmospheric exposure: the aluminum provides barrier protection plus the zinc provides sacrificial protection. Substrate warranties typically run 20–25 years for Galvalume.
Coastal Warning
Galvalume warranties from every major manufacturer exclude installations within ~1,500 ft of saltwater. The salt accelerates corrosion past what the coating can protect against. In that zone, specify aluminum substrate (0.024–0.040″) with stainless steel fasteners — non-negotiable for warranty coverage.
Paint Finishes: PVDF (Kynar) vs. SMP
The exterior paint over the metallic coating is governed by AAMA performance specs. Three you need to know:
- AAMA 2605 — PVDF (Kynar 500 / Hylar 5000): 70% PVDF resin. Gold standard. 30-year chalk and fade warranties. Resists UV via carbon-fluorine bonds (same chemistry as Teflon). Specify for any architectural or high-end residential application.
- AAMA 2604 — Mid-grade PVDF: 50% PVDF resin. Intermediate performance — roughly 10-year color retention. Light commercial only.
- SMP (Silicone-Modified Polyester): ~30% silicone. No AAMA designation. Mid-tier — 20–30 year color life with some fade. Harder than PVDF (more scratch-resistant during install) but the hardness can micro-fracture during roll-forming and expose base metal. Residential standard.
- AAMA 2603 — Polyester / baked enamel: 3–10 year color life. Interior only. Never specify for exterior.
Common trade names: Fluropon (Sherwin-Williams), Duranar (PPG), Trinar (Akzo Nobel) are PVDF/Kynar 500. WeatherXL, Ceram-A-Star 1050, and Signature 200/300 are SMP.
Panel Profiles: Vertical, Horizontal, Exposed, Concealed
Metal siding panels are sold by coverage width — the effective width after side-lap. The actual sheet width is slightly greater to allow the lap. Profiles split into four broad families:
Vertical · Exposed Fastener
Most common metal-siding profile family. Through-screws are visible (rubber-washered). Cheapest install. Includes:
- PBR / R-Panel — 36″ coverage, trapezoidal rib, light-commercial default
- Western Rib / 7.2 Panel — 36″ coverage, deepest exposed-fastener rib
- Ag Panel / Tuff Rib — 36″ coverage, ¾″ rib, lowest cost
- ⅞″ Corrugated — traditional rounded "tin roof" look
- 2½″ Corrugated — bold deep corrugation, 26″ coverage
- 5V-Crimp — Florida/coastal traditional, 24″ coverage
Vertical · Concealed Fastener
Clip-or-batten systems hide fasteners. Cleaner look, higher cost, stricter wind ratings. Includes:
- Board & Batten — 10–16″ coverage with ¾″×2″ raised batten
- Standing Seam (Snap-Lock) — 12–18″ coverage, snaps without seamer
- Standing Seam (Mechanical) — 22–24 ga, hand- or power-seamed
- Flush Wall — smooth flat panels, modern minimalist
- T-Groove / Reveal — recessed shadow line accents
Horizontal Lap
Aluminum or steel panels mimicking traditional wood lap siding. Sold by exposure — the visible face height. Each piece typically incorporates 2 courses molded into one panel:
- Double 4″ — 4″ exposure, ~12 pieces per square
- Double 4.5″ — 4.5″ exposure, ~11 pieces per square
- Double 5″ — 5″ exposure, ~10 pieces per square
- Dutch Lap variant adds a decorative top reveal to each course
Insulated Metal Panels (IMP)
Factory-bonded panels — two metal skins with foam core. Mostly commercial, growing architectural-residential. R-value scales with thickness:
- 2″ panel: R-14 (PIR core)
- 3″ panel: R-21
- 4″ panel: R-28
- 6″ panel: R-42+
Fastener Spacing & Wind Zones
Metal siding fastener spacing scales with wind exposure. The MCA-published baseline for residential panels is roughly 0.8 screws per square foot for 3-foot-wide exposed-fastener panels at 2-foot vertical spacing. In hurricane zones, that density nearly doubles.
| Wind Design | Field Spacing | Edge / Corner Zone | Approx Density |
|---|---|---|---|
| Standard (≤110 mph) | 2 ft o.c. | Same as field | ~0.8 / sq ft |
| Moderate (110–130 mph) | 18 in o.c. | 12 in o.c. | ~1.1 / sq ft |
| High / HVHZ (130–150 mph) | 12 in o.c. | 8–12 in o.c. | ~1.5 / sq ft |
| Extreme (>150 mph) | 8–12 in o.c. | 4–8 in o.c. | ~2.0+ / sq ft |
HVHZ & Florida Product Approval
In Miami-Dade and Broward counties, every exterior wall system must carry Florida Product Approval or a Miami-Dade NOA. Final cladding spacing is determined by the project-specific design pressure (DP) issued by the local building official per ASCE 7. McElroy and other manufacturers report that the single most common cause of hurricane-related metal cladding failure is installers placing standing-seam clips at the 36″ default when engineering specified 18″. Calculator output for HVHZ projects is a planning estimate only — final spacing must match site-specific DP.
Stitch screws (used on exposed-fastener vertical panels) are placed at panel side-laps at 24″ spacing on walls. They prevent wind-driven rain at the lap and keep adjacent panels in plane.
Underlayment, Rainscreen & Ground Clearance
Per IRC R703.1, every exterior wall covering needs a water-resistive barrier (WRB) — either house wrap (Tyvek, Typar) or asphalt-saturated felt #15 / #30 per ASTM D226. Tape all seams; flash all penetrations.
A ventilated rainscreen (⅜″–¾″ gap between WRB and panel back) is best practice, especially for board & batten and flush wall profiles where moisture can't easily escape. Build with 1×3 or 1×4 furring strips at 16″ on center: vertical strips for horizontal panels, horizontal strips for vertical panels. Add bug screen at top and bottom to prevent pest intrusion.
Ground Clearance — IRC R317.1
Never run panels into the ground. Corrosion and capillary water uptake will destroy the base of the panel in a single season.
Trim & Flashing: Measure Every Edge
Metal siding trim is sold and measured in linear feet only — never derive trim quantities from wall area. Every exposed edge requires its own piece. Stock lengths are usually 10′ (120″) or 12′ 6″ (150″). Add 10–15% waste to all trim.
| Trim Type | Where it Goes |
|---|---|
| J-channel | Around windows, doors, top of wall, side terminations |
| Outside corner post | Every external corner × full wall height |
| Inside corner | Every internal corner × full wall height |
| Drip cap / head flashing | Above every window and door head |
| Z-flashing / base | Bottom perimeter (vertical panel siding) |
| Starter strip | Bottom perimeter (horizontal lap siding only) |
| Gable / rake trim | Sloped roof rake × 2 sides per gable |
| F-channel | Length of every soffit-to-wall intersection |
How to Estimate Metal Siding for Your House
Five-step process:
- Measure each wall plane outside corner to outside corner × wall height. For gables, area = ½ × base × rise.
- Deduct openings larger than ~10 sq ft. Always deduct doors and garage doors. Small windows under 12 sq ft can be left in — cut waste around the opening offsets the deducted area.
- Apply waste factor: 10% for simple rectangular walls, 12–15% for gables or complex elevations, 15–20% for diagonal patterns or DIY installers.
- Convert area to panels using the panel's coverage width. For vertical panels: panels = ⌈wall width in inches ÷ coverage width in inches⌉. For horizontal lap: linear feet = area × 12 ÷ exposure inches, then divide by piece length.
- Count every edge for trim — never derive trim from area. Sum linear feet by trim type, divide by stock length, multiply by 1.10.
Or just plug your dimensions into the siding calculator and pick "Metal Siding" — you'll get panel count, fastener count (field + stitch), substrate weight, and HVHZ advisories automatically.
Standards & References
- ASTM A653/A653M — Galvanized steel sheet by hot-dip process (G60, G90, G100)
- ASTM A792/A792M — Galvalume sheet by hot-dip process (AZ50, AZ55, AZ60)
- ASTM E1592 — Structural performance of metal panels under uniform static air pressure
- AAMA 2603 / 2604 / 2605 — Pigmented organic coatings (interior / mid / premium PVDF)
- IRC R703.4 & R703.5 — Code authorization for steel and aluminum siding
- IRC R317.1 — Ground clearance requirements
- FEMA P-499 / ASCE 7 — Wind design and components-and-cladding pressures
- TAS 125 / Florida Product Approval — Florida HVHZ requirements
- UL 2218 Class 4 — Highest impact resistance rating (most metal panels qualify)
- Metal Construction Association — Metal Wall Installation Manual: authoritative U.S. industry reference