Mastering Aluminum Trim Coil Installation: 7 Essential Steps

Aluminum trim coil is an essential element in both residential and commercial construction that provides a mix of durability, weather resistance and aesthetic appeal. For contractors and DIY enthusiasts, understanding the process of installing aluminum trim coil is vital.

This article presents a detailed, seven-step guide with professional tips to help you install aluminum trim coil with ease and achieve results that surpass the average industry standard.

7 Essential Steps to Properly Install Aluminum Trim Coil

1. Equip Yourself with the Right Tools

The journey to a professional-looking aluminum trim coil installation begins with the right tools. A metal brake is crucial for bending the trim coil — for cost-effectiveness, consider renting. In addition, ensure that you have a utility knife, tin snips, trim nails, a hammer and a drill. High-quality tools will help facilitate a smooth, efficient installation and an aesthetically pleasing finish.

Understanding the Metal Brake

A metal brake is a specialized tool used to bend custom metal flashing and decorative trim. It's a common tool among siding contractors and roofers, and while it might appear complex at first, it is essentially a large clamp with a moving hinge.

The metal brake securely clamps the metal, and then a hinge mechanism allows the user to bend the clamped section to the desired angle. The bending mechanism typically involves handles connected to a moving hinge, which, when pulled upwards, induces a bend in the metal held in place by the clamp.

A good quality metal brake can range in cost from $1,300 to $2,500 but can also be rented on a daily or weekly basis for a more economical solution. It is highly effective and efficient because it allows the user to achieve precise bends in the metal without damaging or warping the material.

2. Select Premium Quality Trim Coil

The quality of your chosen trim coil can significantly influence the installation outcome. Opt for a premium quality coil, such as the types offered by Alsco® Metals, for sharp angles, color durability, and scratch resistance. The range of colors and finishes available allows for selection based on specific project needs.

What Makes Alsco’s Trim Coil a Premium Product?

Alsco’s trim coil comes in smooth and PVC finishes and is available in over 150 colors to match or complement those offered by major siding manufacturers. It requires virtually no maintenance as its durable finish protects it from cracking, chipping, flaking and scratching. It is easy to bend when needed but installs smoothly and flatly for an elegant appearance.

Backed by a limited lifetime warranty that covers chalk and fade damage, Alsco’s trim coil is made in the United States with materials sourced locally from Illinois and the Midwest.

3. Precise Measurements

Always be sure to measure twice and cut once to minimize material wastage. Typically, trim coil rolls are 24 inches wide and 50 feet long. Determine the exact length you need, score the coil trim using a utility knife, then bend it at the score line to separate the cut piece.

For superior results, conduct the measuring and cutting on a hard surface, but use care to prevent scratching the coil.

4. Cutting to the Correct Width

After obtaining the correct length, the next phase is cutting the coil to the proper width. Employ the metal brake for precise and neat cuts. If your project requires a 'hem' (a double-thickness edge for reinforcement), add an extra ¾ inches to the total width.

5. The Hem Bend

The hem bend adds strength to the trim piece. To achieve this, mark ¾ inches from the edge of your coil and bend it using the metal brake. A well-executed hem bend not only reinforces your trim but also contributes to a refined finish.

6. Additional Bends and Edges

Depending on the trim's intended location, more bends might be necessary. For example, a fascia piece would need a hem and another 90-degree bend. If it's for window or door trim, be sure to measure the length needed for each bend and account for flaps for nailing into the house.

7. Fastening the Trim Coil

Fastening the aluminum trim coil is typically done using aluminum trim nails. If you're working with treated lumber, cover the wood with house wrap or felt paper before fastening to protect it from the elements.

Recommendations for Professional Results

  • To prevent bulging or buckling caused by temperature changes, it's important to remember that aluminum expands when temperatures rise and contracts when temperatures drop.

  • Custom bends, particularly longer ones, need to have enough space to slightly move. It's recommended to leave around 1/16 of an inch between the ends of the bent coil stock and fixed objects like inside corner walls.

  • When nailing shapes into place, use painted aluminum or stainless steel trim nails and make sure to drill oversized nail holes. Avoid nailing too tightly and always ensure that nails penetrate the wood at least ¾ inches.

To elevate your results above the average contractor, consider these tips.

  • Always prioritize the quality of your trim coil and tools, as these factors will directly impact the installation outcome.

  • In your measurements, be as precise as possible and adhere to the “measure twice, cut once” principle. The more practice you get in making the hem and additional bends, the more professional your results will be.

Mastering the installation of aluminum trim coil takes time and practice, but by following these steps and recommendations, you can create installations that stand out.

Achieve Professional Results with Premium Alsco Aluminum Trim Coil


For exceptional results that surpass industry standards, trust Alsco Metals for your aluminum trim coil needs. We also carry roofing siding and trim products made to exceed industry standards and backed by a limited lifetime warranty.

Contact us today for advice and more information on our entire product line!