Is the Northwest Door Infinity Classic 7800 a steel or aluminum garage door?

The Northwest Door Infinity Classic 7800 is built entirely from aluminum, not steel. The frame uses 6063-T5 extruded aluminum, and the panels are 0.050-inch thick aluminum. This is a deliberate design decision, not a cost-cutting choice. The 7800 is a premium carriage-house door built for custom residential projects and traditional homes where material quality, finish options, and architectural detail take precedence over maximum thermal resistance.

Understanding why aluminum was chosen, what it offers compared to steel, and how the 7800 performs in Colorado's climate is the right framework for evaluating whether this door fits your situation.

Why Aluminum, Not Steel?

The 7800 is a carriage-house door with premium finish and customization options. Aluminum brings specific advantages in that context.

6063-T5 extruded aluminum is an engineering alloy. The 6063 designation identifies the alloy composition: aluminum with magnesium and silicon. The T5 designation means the material is air-cooled from the forming process and then artificially aged to build strength. The result is a frame with high stiffness, good corrosion resistance, and excellent powder-coat adhesion. This alloy is used in architectural window frames and curtain wall systems for similar reasons.

Aluminum vs. steel in carriage-house applications:

Feature	Infinity Classic 7800 (Aluminum)	Typical steel carriage door
Frame material	6063-T5 extruded aluminum	Steel (25 or 27 ga typical)
Rust resistance	Natural (passivation layer)	Requires galvanizing and paint
Weight	Lighter	Heavier
Custom arched top availability	Yes	Rarely offered
Simulated divided lite windows	Yes	Rare
Woodgrain powder coat options	8 options	Limited
Typical R-value	R-5.6 (with insulated windows)	R-6 to R-17 depending on model

The aluminum frame enables design features that most steel carriage-house doors cannot offer. Custom arched tops fit radius-top masonry openings without a filler panel above the door. Simulated true divided lite windows create a multi-pane appearance that is structurally integrated into the door rather than achieved with a grille overlay. These details set the 7800 apart in the premium segment.

Construction of the 7800

The door section is 2 inches thick. The 3-layer construction uses aluminum on both the exterior and interior faces with a 1/2-inch EPS polystyrene core in the panel section.

R-value: With optional insulated thermo-pane windows installed, the assembly achieves an average R-value of R-5.6. This is lower than most insulated steel doors at mid-range pricing. The gap comes from aluminum's thermal conductivity. Aluminum conducts heat more readily than steel at the same section dimensions. The frame area of an aluminum door reduces the whole-assembly R-value below what the foam core alone would provide.

Panel configurations: The 7800 is available in 2-panel, 3-panel, and 4-panel horizontal section counts. Optional V-groove insulated panels add texture within each section. The custom arched top option accommodates radius-top openings.

Standard finish: White Polycron III, a premium painted finish used in architectural applications. The Polycron III designation indicates a high-durability polyester finish.

Color and Finish Options

The 7800's color range is one of its most distinctive features.

Woodgrain powder coats (8 options): Mahogany, Dark Walnut, Dark VG Fir, Light VG Fir, Dark Ash, Light Ash, Dark Cherry, Light Cherry.

Powder coat is applied electrostatically and cured at high heat. The result bonds to the aluminum frame surface. It cannot peel or chip the way liquid paint can. On a carriage-house door where the grain texture and tone of the finish are central to the visual appeal, powder coat's durability at Colorado's UV-intensive elevations is a meaningful advantage.

Solid color powder coats are available beyond the standard Polycron III white.

Glass and Window Options

Standard glass: 1/8-inch clear tempered glass. Tempered glass is four to five times stronger than annealed glass of the same thickness and breaks into small granular pieces rather than sharp shards if it fails.

Optional glass types: - Insulated thermo-pane (required for R-5.6 rating) - Tinted: Grey, Bronze - Obscure: Mistlite, Satin Etch, P516, Gluechip, Greylite, Rain - Custom thicknesses up to 9/16 inch - Simulated true divided lites

Simulated true divided lites create the appearance of individual separately-framed panes. The dividers are structural components integrated into the window unit, not just a grille overlay on a single pane. On a traditional carriage-house door, that detail reads as authentic craftsmanship.

How the 7800 Performs in Colorado

Rust and corrosion: Aluminum passivates naturally. When the surface is exposed to air, it forms a stable aluminum oxide layer that prevents further oxidation. Road salt from Denver's winter de-icing does not penetrate the passivation layer. An aluminum door frame does not rust even if the powder coat is scratched.

Temperature cycling: Aluminum expands and contracts with temperature at a predictable rate. Colorado's rapid temperature shifts between morning lows and afternoon highs are consistent across the Front Range. Aluminum handles those cycles without absorbing moisture, which eliminates the swelling and gapping that affects wood trim in similar conditions.

UV resistance: Powder coat at Colorado's elevation holds color better than liquid paint because the cured coating resists UV degradation more effectively. For a door with woodgrain powder coat where color fidelity is part of the appeal, that durability matters.

Hail consideration: Aluminum panels can dent under large hail. The 0.050-inch aluminum panel face is thinner than a 24 or 25-gauge steel panel at equivalent weight. Homeowners in high-hail-exposure neighborhoods should factor this into the decision. For most Front Range locations, typical hail events produce manageable results on aluminum. Severe hail events (1.5 inch diameter and larger) can dent any residential door material.

Thermal performance for attached garages: The R-5.6 rating is lower than many steel-door alternatives. For attached garages where energy efficiency is a priority, higher-R steel options should be compared. The 7800 is strongest for detached garages, carriage houses, and applications where design quality and architectural detail outweigh thermal optimization.

G Brothers installs the Northwest Door Infinity Classic 7800 in the Denver metro and across the Front Range. Free estimates cover configuration decisions including panel count, arched tops, woodgrain finish, and glass type. Licensed and insured, same-day service on most repairs, 24/7 emergency response.

Arched top installation requirements: The custom arched top option on the 7800 requires the masonry or frame opening to have a true radius top. G Brothers measures the radius of the opening during the estimate to confirm it matches an available arched top configuration. If the opening has an irregular or non-standard arch, that measurement informs whether a stock arched top fits or whether a custom fabrication is needed. This process happens before the order is placed, not after.

Woodgrain powder coat and home matching: The eight woodgrain options in the 7800 span a range from light and cool (Light Ash, Light Fir) through warm mid-tones (Light Cherry, Mahogany) to deep and rich (Dark Walnut, Dark Cherry, Dark VG Fir). Matching the door's woodgrain tone to other wood elements on the home, such as front door stain, window trim, or soffit material, is the most common design goal. G Brothers can bring finish samples to the estimate for side-by-side comparison.

Simulated divided lites and architectural detail: On higher-end custom homes in Denver's established neighborhoods, the visual difference between a grille overlay on a single pane and true simulated divided lites is meaningful. Simulated divided lites create individually framed panes within the window unit. The dividers are structural elements, not adhesive-backed trim. From the street, the effect reads as authentic multi-pane glazing. That detail sets the 7800 apart from most residential carriage-house alternatives in the same price discussion.

Weight and spring sizing: The 7800's aluminum construction keeps the door lighter than a comparable steel carriage-house door. Spring sizing is still important. G Brothers confirms spring requirements at the estimate and calibrates torsion springs to the door's specific weight at installation.

Quick summary: The 7800 is an aluminum door. The frame is 6063-T5 alloy. It does not rust. The R-value is 5.6. It is lighter than steel. It suits custom and high-end homes. It comes in many wood-tone colors. The arched top is a popular option in Denver. G Brothers stocks samples and can bring them to your home.

Is the 7800 the right door? It is if you want aluminum. It is if you want a carriage look. It is if you want wood tones. It is if rust is a concern. It is not the top pick for insulation. For high R-value, look at steel doors. But for curb appeal and low upkeep, it is hard to beat. G Brothers can help you decide. The estimate is free. Call or book online.