When we mention a metal roof, we'll forgive you for imagining flat, dull sheet metal…
After being relegated in preference for Asphalt Composite Shingles, metal roofing panels are steadily becoming many homeowners’ popular roofing choice. This is especially true because they are durable and cheap to manufacture.
Would you like to understand the process of metal roofing panels manufacturing? Well, there are typically two stages in making a metal roofing panel. One is manufacturing of the metal sheets and the other is shaping the metal sheets.
The two stages are nuanced because many considerations go into the kind of metal roofing you want to be done on your building. Once you decide on what you want to go with, your contractor will figure out what needs to be sourced, and from where.
To clearly understand how these roofing panels are made, we will start from the source of the metal roofing sheet.
Manufacturing of Metal Roofing Panels
Metal roofing panels are made from alloys of various metals like steel, iron, copper, zinc, and aluminum. At Prime Roofing, they use 0.40” aluminum or 24 gauge steel for metal roofing trims.
In this outline, we will delve into steel because the process is generally the same for all the metal varieties used in roofing.
Steel is made from iron ore by iron ore-producing companies. Before it finds its way to your roof, the steel has to be extracted and taken through various stages of refinement before the trims are fitted on your roof by the building contractors. The extracted steel is then delivered to the roofing company for use.
Processing at the Roofing Companies
Roofing companies receive extracted steel in thick coils, which they then have to reduce to the required thickness used for roofing—generally between 22 gauge and 28 gauge for steel, after which the metal is galvanized and painted in four processes:
First, the coil is galvanized by dipping it in a hot mixture of molten zinc and aluminum. The galvanized steel is heated and allowed to cool in a process called annealing. Annealing makes it soft to be rolled to form standard coils for delivery to sheet metal fabrication shops.
Secondly, the standard coil is painted using the first coat of paint –the solar reflective Kynar 500, following which it is cleaned and dried pristinely for the next process.
Third, a primer is applied to the standard coil on both sides and baked into it in an oven. The two processes are repeated to improve the quality of the primer application.
Then lastly, the primary color is applied to the upper side of the coil. The lower sometimes get a white color applied to it, but this is not always the case.
Sizing and Shaping Metal Roofing Panels
The metal coils received from the roofing companies are ready for use, but they first have to be made into shapes and sizes unique to the requirement of the prospective buyer. Either the contractor does this on site or outsources the work to sheet metal shops depending on the parts of the metal sheet the contractor requires for the roof.
Flashing material, gable trim, drip edge accessory, sidewall, chimney and ridge caps are made in the sheet metal shop because they are complicated and require precise detailing to make. Alternately, the most typical metal roofing kind used is the standing seam metal roof that can be made on site, which is why contractors like this kind of roof.
The standing seam metal roof is made on site from the standard coil using a roll-forming machine.
In the shop, they have roll-forming machines, hydraulic shears, sheet metal breaks, and specialized racks for storage of final products, among other smaller tools and factory machinery.
The roll-forming machine (used for making standing seam metal roofing sheets) is used either on the shop or out in the site. In the shop when the site is far and on site if it is close enough for convenient roofing.
The machine flattens and then shapes the metal roofing sheet into different standing seam profiles. It also cuts the sheet into the specified lengths and widths to be used for roofing. The sheets are specially designed to maintain the paint on the coil even as they are bent and curved. This engineering makes sure that the paint does not crack and expose the metal to corrosion and rust.
The hydraulic shear is used when cutting the sheet into pieces used to make flashings with the metal breaks.
Flashing materials are made in the shop using sheet metal brake machines. These machines can either be manual or computerized. Manual metal brakes require more labor input and take more time because all the measurements must be taken manually while bending and cutting the metal sheet. They also produce flashing that is not consistent and accurate due to human error. Computerized sheet metal brakes, on the other hand, are more precise and quick. They have variable slits that only allow the sheet to be inserted up to the length required for the flashing under processing.
Specialized storage racks keep the finished products in their state, preventing physical damage or corrosion. Machinery like forklifts and conveyor belts are also used in the factory.
In a Nutshell
The processes involved in making metal roofs are determined by the homeowner. By extension, the person contracted to build the house makes the more specific choices on behalf of the client.
The roofing expert decides what parts will come together to match the client’s taste and fit into their budget. Whether the roofing profile will be a snap lock standing seam, a mechanical lock standing seam, or whether the roof will be steel or aluminum; changes the mechanism the ore will take to the roof of the building.
The machinery involved and the places where the flashings, trims, drip edge, and the gable will be made also change dramatically. These variables factor into the process.