Aluminum Fence vs Wrought Iron Decision

Why this matters

Customers ask for "wrought iron" when they want the look. Nine times out of ten what they actually want is aluminum painted black. The wrong answer here costs the contractor in two ways: quote too high (push the customer to a competitor selling extruded aluminum at a fraction of true wrought iron cost) or quote too low (deliver a thin-extrusion aluminum panel system on a property where the customer wanted the heft of real iron and the result is a callback). Understanding the actual material differences and matching to use case is one of the highest-value skills in ornamental fencing. The decision turns on rust behavior, structural strength, repairability, weight, and where the fence will live for the next thirty years.

What "wrought iron" actually means

Historic wrought iron is a low-carbon iron with slag fibers (less than 0.08 percent carbon, fibrous structure from puddling). It rusts slowly, can be hot-forged, and is essentially unavailable today. The last commercial wrought iron production in the US ended decades ago.

What gets sold today as "wrought iron fencing" is either:

Mild steel fabricated and painted (the actual modern wrought-iron-look product, properly called steel ornamental fencing). Often 14 to 20 gauge picket, 11 to 16 gauge frame. Welded or assembled with mechanical fasteners. Painted with industrial enamel.

Cast iron components (decorative finials, post caps, scrolls) attached to mild steel framing. The cast parts give the heavy historic look, the steel framing carries the load.

True wrought iron, only when salvaged from old fence sections and refurbished. A small specialty market exists for restoration projects on historic homes.

When a customer says wrought iron, ask what they expect: the look, the weight, the historic accuracy, or all three. The answer dictates the spec.

Aluminum ornamental fencing

Modern aluminum ornamental fencing is extruded 6063-T6 (or sometimes T5) aluminum picket, rail, and post. Extrusion thickness varies by grade:

Residential grade: pickets 0.045 to 0.062 inch wall, rails 0.062 inch wall, posts 0.062 inch wall. Light, easy to install, adequate for typical residential pet and aesthetic fencing.

Commercial grade: pickets 0.062 to 0.078 inch, rails 0.078 to 0.095 inch, posts 0.094 to 0.125 inch wall. Stiffer, holds line better on longer runs.

Industrial grade: pickets 0.078 inch and up, rails 0.125 inch and up, posts 0.125 inch and up. Used for pool code compliance with vertical-only pickets, security fencing, and tall (6 foot and above) ornamental runs.

Aluminum does NOT rust. The 6000-series alloy forms a passive aluminum oxide layer in air that resists corrosion. Coastal exposure with chlorides creates some pitting on uncoated aluminum but the structural section loss is negligible over decades.

Powder-coat finish on aluminum is typically 2 to 4 mil thick polyester powder, baked on, with a 10 to 20 year manufacturer warranty against chipping, peeling, or fading (the warranty terms vary by manufacturer; Ameristar, Jerith, and Specrail all publish their warranties on residential ornamental aluminum).

Steel ornamental fencing (modern "wrought iron")

Mild steel ornamental fencing is welded from hot-rolled or cold-rolled steel sections. Typical residential steel ornamental:

Pickets: 1/2 inch solid square bar or 5/8 inch solid square bar (vs hollow aluminum pickets). The solid steel picket weighs roughly 4 to 6 times what an equivalent aluminum picket weighs.

Rails: 1 inch x 1 inch x 1/8 inch wall steel tube, or U-channel cold-rolled steel.

Posts: 2 inch or 2-1/2 inch square steel tube, 1/8 inch or thicker wall, set in concrete.

Steel WILL rust if the protective coating fails. Coating options range from primer + enamel paint (cheapest, shortest service life) through hot-dip galvanizing per ASTM A123 (15 to 50 year service life depending on coating thickness and exposure) to galvanized + powder coat (best of both, typical for premium steel fencing).

A well-coated steel fence in a non-coastal climate can last 50+ years. A poorly coated steel fence in coastal salt-spray exposure can show through-rust on pickets in under 5 years.

Weight, shipping, and labor

Per linear foot of 4 foot tall fence:

Residential aluminum: roughly 5 to 8 lb/ft. Commercial aluminum: roughly 10 to 14 lb/ft. Steel ornamental with hollow pickets: roughly 12 to 18 lb/ft. Solid-picket steel ornamental: roughly 20 to 30 lb/ft.

Steel ornamental panels in standard 6 foot or 8 foot widths require two people to carry and set; aluminum panels are routinely one-person lifts. The labor difference is real over a 200 foot run.

Shipping: aluminum panels nest tighter on pallets and ship cheaper. Steel panels often require freight LTL for any quantity. Account for the freight in the quote.

Code: pool fences and IRC R326

IRC R326 (referencing ISPSC) and many state pool codes require fencing around residential pools to have a maximum 4 inch sphere opening between pickets, a 1-3/4 inch opening at the bottom rail, and a top rail height of at least 48 inches. Both aluminum and steel ornamental fencing can meet this, but the picket spacing on stock fence panels varies.

Standard ornamental "decorative" panels often have wider picket spacing that fails the pool code. Pool-rated panels (sometimes called "BOCA spec", "ASTM F2200 compliant", or "pool code") have tighter picket spacing (3-7/8 inch maximum opening). Specify pool-rated panels for any pool enclosure, regardless of aluminum or steel.

Repairability and parts supply

Aluminum: damaged pickets can be replaced individually on rackable panels but typically the panel has to come down. Welded rigid aluminum panels (less common in residential) require panel replacement. Most aluminum manufacturers stock parts for 10 to 20 years; discontinued styles are a problem on long-term repairs.

Steel: highly repairable in skilled hands. A bent picket can be straightened, a corroded section cut out and welded in. Touch-up paint is a standard maintenance task. A welder + grinder + paint can refurbish a 50-year-old steel fence section that no aluminum equivalent could be salvaged from.

If the homeowner expects the fence to outlive multiple owners (historic property, family estate), steel wins on long-term serviceability. If the homeowner expects to replace in 20 to 25 years anyway, aluminum is the right value choice.

When to specify which

Aluminum if:

References

• IRC 2021 Section R326 Swimming Pools, Spas, and Hot Tubs (referencing ISPSC)
• ISPSC 2021 Section 305 Barrier Requirements
• ASTM A123 Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products
• ASTM F2200 Standard Specification for Automated Vehicular Gate Construction (referenced for gate code)
• Ameristar Industrial Fence Specifications current edition (commercial and residential ornamental aluminum and steel)
• Jerith Manufacturing Aluminum Fence Installation Guide current edition
• Specrail Aluminum Fencing Specifications current edition