How to Install Aluminum Trim Coil

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Things You'll Need

  • Sheet metal brake

  • Aviation snips

  • Utility knife

  • Straightedge

  • Coated aluminum nails

  • 3/4-inch exterior grade wood

  • Thick work gloves

  • Safety goggles

Use aluminum trim coil to create practical design features on your home exterior.

Many sheet metal manufacturers produce aluminum trim coil that you can install on your house to cover base materials to provide a finishing feature. Typical uses include the trim for windows, soffit boarding, siding and roof edging. Aluminum trim coil comes in a large range of colors, widths and gauge thicknesses to complement your trim design needs. Knowing how to install the trim allows you to create a professional finish that is durable and cost-effective over the long term.


Step 1

Take length measurements of the trim features, such as the top of the window and soffit lengths, to determine the required size for the sheet metal brake. A sheet metal brake is a simple mechanical device that clamps and bends thin metal, which you need to bend the aluminum trim coil. Typically, tool hire outlets rent out up to 12-foot long sheet metal brakes that produce quality bends and save you time when you are creating the trim shape.

Step 2

Cut the aluminum trim coil to the required length using aviation snips or a utility knife depending on the metal thickness. Use a straightedge to guide the utility knife to make a neat cut. Create a curve in the aluminum to produce a rounded trim edge by using the aviation snips.


Step 3

Measure and pencil mark the aluminum coil trim length where you need to shape a bend to cover the base substrate, such as over a J-channel fixing or over a roof edge. Position the aluminum in the sheet metal brake and bend the aluminum according to the brake manufacturer's instructions, as these differ between companies. Typically, you clamp the metal and apply leveraged force to the aluminum to create the bend.

Step 4

Fasten the aluminum trim with coated aluminum nails that match the trim color to blend in the fastening points. Ensure you leave a standard 1/16-inch gap between the side edge of the trim and protruding features such as a door frame so that the aluminum can expand and contract in different ambient temperatures. Install the trim into an exterior-grade wood substrate to a standard depth of 3/4 inch, leaving a 1/16-inch gap behind the nail head to allow for natural aluminum expansion.


Overlap lengths of trim away from the prevailing wind to increase the longevity of the product and to maintain water-tightness.


Wear thick work gloves and safety goggles to protect against injury from sharp aluminum edges.



Jane Humphries

Residing in the coastal county of Devon, England, Jane Humphries has been writing since 2004. Writing for "British Mensa" nationally and regionally, Humphries has also held key roles within the High IQ Society. She received a Bachelor of Science, honors, in psychology with combined studies covering biology, statistics, economics, politics and sociology.