Restoration Guide: Aluminum and Steel Siding for Exterior Walls

Rob Sabo

Editor's Note: This is article 8 of 18 in the Exterior Walls chapter of Old House Web's Restoration Guide. This guide was developed and edited for old homes from original material in the U.S. Housing and Urban Development (HUD) Rehab Guide.


Section 1--Overview

Aluminum and steel siding became popular in the 1950s and '60s as a cost-effective choice to cover deteriorated wood siding. Both metal siding types often were manufactured with a thin lining of foam designed to increase the insulation value of the siding. However, because of the thinness of the foam lining and the extremely high thermal conductivity of metal, aluminum and steel siding offer inherently poor insulation values.

Use of aluminum siding has declined drastically with the advent of vinyl and fiber-cement siding--so much so that metal siding now accounts for just 1 percent of the new siding market. Metal siding is still found in the Midwest, where it's aptly suited for resisting intense hailstorms and temperature extremes that permeate that region of the country. It also has a foothold in metropolitan areas where building codes require non-combustible wall claddings.

If you are remodeling an old house with aluminum or steel siding, it's likely there are areas on the home's exterior that require cleaning, maintenance, or replacement of damaged siding.

Section 2--How to Clean and Maintain Metal Siding

2.1: Basic Cleaning

A bucket, garden hose, laundry detergent such as Tide (about 1/3 cup to a gallon of water), and a soft brush are the best tools to use to maintain and clean metal siding. For grease spots or heavy grime, try using a non-abrasive cleanser such as Simple Green, Spic-N-Span, or Zud Heavy Duty Cleanser powder.

2.2: Heavy-duty Cleaning

Mineral spirits are best for removing old caulking, tar, wood sap, and similar problem areas. Extremely troublesome areas may require some light scraping with a putty knife, but be careful not to scar the siding.

Always clean from the bottom up, and start the task before the sun heats the siding.

Section 3--Repairing Damaged Metal Siding

3.1: Patch Repairs

Aluminum siding is much more prone to damage by impact than steel siding--but patching aluminum siding is an easy fix. Here are five steps to replace damaged areas of siding during your home renovation:

  • Cut the damaged piece along its center with a razor knife or tin snips.
  • Remove the bottom portion of the damaged section.
  • Cut the top lock off a new panel.
  • Apply a thick bead of sealant used for rain gutters, such as Geocel or Gutterseal, along the length of the defective panel.
  • Press the new panel in place over the damaged section.

A word of caution, however: New materials won't match the look of existing metal siding, so consider replacement carefully before undertaking the task.

3.2: Small Dent Repairs

To pull out small dents, drill a hole using a 1.8-inch drill bit, insert a sheet metal screw halfway, and pull on the screw head with vice-grip pliers until the dent pops out. Use Bondo auto-body filler to patch the hole, and spot-paint with a metal-siding-specific paint such as Calbar in a color tone that best matches the body of the house

Section 4--Using Steel Siding to Cover Existing Siding

Steel siding is one of the strongest siding materials on the market. It stands the test of time against extreme temperature fluctuations, wind, and other problems common to wood siding, such as cracking or bending. Steel siding can be used directly over existing siding, or it can be attached to furring strips to cover existing stucco or masonry walls. Many steel siding installers also roll-form panels on site to desired lengths to avoid vertical joint lines.

Steel siding typically comes pre-finished and doesn't require painting. Its drawbacks are that it's about 30 percent more costly than vinyl siding and has fewer trim and style choices due to a limited number of manufacturers.

Section 5--Using Aluminum Siding to Cover Existing Siding

Aluminum is quickly become a niche market. Like steel, it has a limited range of styles and color choices. Aluminum siding can be used to cover damaged wood siding, and it's less likely to have waves due to uneven wall studs than vinyl siding.

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