Before 1829, metal was rarely used as a roofing material since it would often warp or dent when exposed to the elements. All this changed with the invention of corrugated iron. Today, it is one of the most common metal roofing options available.
Corrugated metal roofing is relatively cheaper and easier to install when compared to other roofing options such as standing seam. In this article, we tell you all about this type of metal roofing. We also answer some of the most frequently asked questions.
What is a Corrugated Metal Roof?
Corrugated metal roofing is one of many types of metal roofs. It features sheets that have undergone roll forming to create round and wavy panels that are more sturdy and durable. These panels are attached to the roof deck using exposed fasteners.
This type of metal roofing is preferred for its lightweight, durability, energy efficiency, and the fact that it is easy to install. It is an excellent alternative to asphalt shingles or clay tile roofs. Although it is a popular choice for roofing, people also use it for siding projects.
The term corrugated metal roofing is often mistakenly used to refer to all metal panels with roll-formed grooves and ridges. That generalization lumps corrugated metal panels together with their cousins—ribbed metal panels.
Corrugated VS Ribbed Metal Roofing?
Ribbed metal roofing and corrugated metal roofing belong to the same family. They all have grooves and ridges and are manufactured similarly. Moreover, the installation process is similar, and they cost relatively the same.
The only notable difference between the two is the shape of the grooves and ridges. Corrugated metal roofing panels have U-shaped and sometimes V-shaped corrugations. On the other hand, you could mistake ribbed metal roof panels for standing seam metal panels. The raised grooves are fewer, and the spacing between the ridges is wider.
How is Corrugated Metal Made?
Corrugated metal roofing is either made from galvanized steel or aluminum. The panels are manufactured through a process called roll forming.
First, plain sheets of metal are put in a machine that has rolling dies. The rollers then shape the metal to create round and wavy panels. Afterward, the excess length is sheared off to get the desired panel length.
Corrugating metal gives it considerable structural strength. If you want panels with different shapes, all you have to do is change the rolling dies.
Corrugated Metal Roofing Dimensions
Corrugated metal roofing comes in a wide variety of options as far as size is concerned. You can choose different lengths, widths, and thicknesses depending on your unique needs.
Corrugated Metal Roofing's Length
Corrugated metal panels are available in standard lengths of 8, 10, and 12 feet. But you can also get customized sizes depending on the nature of your project.
Corrugated Metal Roofing's Width
The width is measured from one edge of the panel to another without following the ridges and grooves. Different corrugated panels will vary in size, but the most common widths are 26 and 36 inches. Other popular standard widths include 24 and 39 inches.
When measuring the roof coverage, remember each panel will overlap the other by two grooves. For instance, a 39-inch panel will only provide a roof coverage of 34.67 inches. Similarly, a 26-inch panel will only cover 21.33 inches.
Corrugated Metal Roofing's Thickness
The thickness of the corrugated metal panels is measured in gauges. Remember, the lower the number, the thicker the gauge. Therefore, a higher number indicates a thinner gauge. The standard gauges include 18, 20, 22, 24, and 26.
Types of Corrugated Metal Roofing
Corrugated metal roofing manufacturers will offer different metal panels depending on the seam height. Examples include 7/8, ¾, ½, and ¼ inch panels, with the most common being 7/8 inch panels and 1/2 inch panels.
7/8 Inch Corrugated Roofing
7/8" is the most common type of corrugated roofing panel. Apart from being the toughest, it is also the least expensive option available. Moreover, its deep ridges produce a beautiful shadow-like effect.
The 7/8 inch corrugated panel has a seam height of 7/8 inches, and the centers of adjacent corrugations are 2.67 inches apart. The metal panels are either 39 or 37 inches in width, depending on the manufacturer.
After accounting for the overlap, a 39-inch panel should give you a roof coverage of 34.67 inches. That means you will have to buy an additional 10 to 12% of roofing material to cover the entire roof.
½ Inch Corrugated Roofing
Before the 7/8 inch corrugated roofing gained prevalence, the 1/2 inch was the most popular option. It is still available today, but it is not as prevalent.
The panels have a seam height of ½ inches, while the grooves are 2.67 inches apart. Although the size may vary depending on the manufacturer, 26 inches is the most common width.
A 26-inch wide panel will only cover 21.33 inches of the roof because of overlapping. That means you will need 23% additional roofing material to cover the entire structure.
Advantages of Corrugated Metal Roofs
Installing a corrugated metal roof as opposed to other types of roofing presents several advantages to the consumer. They include:
Easy to Install
Corrugated metal roofs are easier to install compared to concealed fastener systems. There are fewer accessories, and the installation does not require specialized skills.
Cost-Effective
Corrugated metal roofing panels are cheaper compared to metal tiles and standing seams. Moreover, the installation process will cost less since minimal labor and expertise are needed.
Availability
Corrugated metal is one of the most, if not the most, common types of metal roofing. Therefore, you will not have a hard time finding the panels you need in your local home improvement store.
Multiple Color Options
The panels are available in multiple premium color options in Kynar 500 paint finish. Moreover, you can even order custom colors.
Energy Efficient
The grooves and ridges on the metal panels reflect more UV light and heat. Since less heat permeates inside the building, you can save a lot on cooling bills during the summer.
Disguises Oil Canning
Oil canning is less visible on corrugated metal panels compared to other flat panels. The multiple ridges and grooves help mask such deformities.
Disadvantages of Corrugated Metal Roofs
Corrugated metal roofs also have several drawbacks. They include:
Exposed Fasteners
The screws can become loose because of improper installation or after continuous thermal movement. Therefore, every exposed fastener is a potential leak point.
Requires Regular Maintenance
Corrugated metal roofs require more frequent maintenance compared to other roofing options. That’s because loose and damaged fasteners need replacements now and then.
Not Suited for Flat Roofs
Flat roofs do not drain water fast enough. When you pair one with exposed fasteners, it increases the risk of leaking, thus leading to expensive roof repairs.
Aesthetics
Although looks are subjective, corrugated metal roofing might not be the most aesthetically pleasing option due to the exposed fasteners. At least not when compared to the modern, sleek look of concealed fastener roofs.
What are its Common Applications?
Initially, corrugated metal roofing was prevalent in agricultural and commercial applications. You would often find it on barns and industrial structures, both as a roof and siding option. Today, it has become a popular choice for residential applications. It is a favorable option, especially in situations where money and time trump appearance in importance.
Corrugated Metal Price Analysis
A corrugated metal roof is the cheapest metal roofing. However, the price can vary depending on the gauge of the metal panel and the type of paint finish. The 24 gauge panels often have a Kynar paint finish. On the other hand, 26 gauge panels come with an SMP paint finish.
If you want to buy a 26 gauge panel with an SMP paint finish, expect to pay between $1 and $1.25 per square foot. On the other hand, a 24 gauge panel with a Kynar paint finish will cost between $1.50 and $2 per square foot. All the prices are exclusive of installation costs.
You would have to pay between $4.50 and $5.50 per square foot to cover the installation costs. Overall, the total cost of materials plus the installation will fall somewhere between $5.00 and $8.00 per square foot, depending on the type of panels you buy.
Do Corrugated Steel Panels Rust?
Corrugated steel panels are galvanized (coated with zinc) with a Kynar 500 paint or acrylic paint finish. That prevents oxidation, which leads to corrosion. However, the protective layer on the metal will eventually wear off, thus exposing the steel to rust.
How Do You Remove Rust from Corrugated Iron?
When the protective zinc coating wears off over time, it will expose your iron roof to moisture and speed up the rusting process. But it is possible to get rid of the rust.
If you are only dealing with small patches of rust here and there, a brush and sandpaper will do the trick. However, take care not to use them on the protective coating to avoid stripping it away.
If the rust is widespread, consider using oxalic acid. Use a spray hose to apply a concentrated solution of the acid to the affected areas. Afterward, rinse the area with water. The rust will simply drain away.
How Do You Add Patina to Corrugated Metal?
If you don't like the plain look of corrugated metal, you can add patina to achieve a vintage look. But you will need to strip off the galvanized steel first. Here, you can either use muriatic acid or vinegar to achieve this.
To add patina, degrease the surface to remove any debris, dirt, and any remaining finish. Afterward, spray the metal with a solution of vinegar, 3-percent hydrogen peroxide, and common salt and leave it to dry before reapplying. Repeat the process severally.
Final Thoughts
Corrugated metal roofing has come a long way over the years. While old steel panels could develop unsightly rust and leaks, modern corrugated panels are zinc coated and finished with Kynar 500 or acrylic paint to prevent corrosion.
If you are looking for the cheapest metal roofing option that is easy to install, you could never go wrong with this type of metal roofing. It is available in different sizes, styles, colors, and finishes. And it can fit all kinds of projects, whether commercial, agricultural, or residential.