By: Lauren Risotto on April 10th, 2020
Exposed Fastener Roof Panels: Corrugated vs. R-Panel (PBR)
A metal roof is an investment that can last for 40-60 years and will pay for itself over time. However, the initial high upfront cost might scare some people into choosing a less expensive roofing option. Luckily, there are different types of metal roofs that can accommodate smaller budgets but still provide all of the benefits of a metal roof.
⅞” Corrugated and R-Panel are metal panels that were both originally designed to be a readily available, low-cost option for agricultural applications. Over time, they have become more versatile and today are a popular choice in residential and commercial roofing and siding for their affordability. Both panels are at least half the cost compared to a premium metal roofing panel such as standing seam.
At Western States Metal Roofing, we manufacture both ⅞” corrugated and R-panels. Quite often, we are asked questions on the differences between the panels. While the panels are similar, there are also some key differences.
We will go over how corrugated and R-Panel compare in terms of:
- Panel Appearance
- Fastener Placement
- Panel Strength
- Panel Applications
- Cost and Sidelap
Understanding the differences between R-Panel and ⅞” corrugated will allow you to make an easy decision on the right metal panel for your home.
Corrugated metal roofing panels are traditionally round and wavy, although corrugated could mean any type of metal that is formed into grooves or ridges. For ⅞” corrugated, the waves are each ⅞” high and evenly spaced 2.67” apart. Corrugated panels come in a wide range of colors in either SMP or PVDF paint systems.
R Panels feature 36” panels that have raised ribs with a flat area between the ribs.
R-Panels are similar to PBR Panels, with one notable difference. The PBR panel also includes an overlap section, known as a purlin bearing leg, that enhances the strength of the panel and makes the panel more weather tight. R Panel is mainly used for wall or siding applications and PBR panel should be used for a roof or a wall.
The cost difference between these two panels is less than 2%, so you will find that many manufacturers usually will only offer PBR panels as they can be used in both roofing and wall applications.
Both R-Panel and corrugated have exposed fastener systems. The metal roofing panels are fastened to the plywood roof deck with screws that penetrate the panels, the screws are left visible.
7/8” Corrugated Fastener Placement: Siding v. Roofing Application
When it comes to corrugated metal roofing, the placement of the fasteners depends on what the panel is being used for.
For corrugated metal siding (wall application shown first above), the fasteners are placed in the lower part of the groove, or “the low”.
For corrugated metal roofing (shown second above), the fasteners are placed in the high part of the groove.
The difference in fastener placement serves different purposes depending on the application. When the fastener is placed in the low of the corrugations, there is a more secure attachment of the panel to the structure compared to when the fastener is placed in the high of the corrugations..
When the fastener is placed high, it makes the panels more weathertight. The water does not drain past the screw. When the screw is located in the low it acts like a dam. The low of the panel is narrow and the screw takes up almost the entire low of the corrugation. When it rains the water will pass over the screw. If the screw is installed incorrectly or if it has backed out over time it will leak, resulting in costly repairs. By installing the screw in the high of the panel it lessens this problem significantly.
If you have further interest in this we suggest that you read:
How Many Screws Do I Need For Metal Roofing? Spacing & Placement Best Practices
R-Panel Fastener Placement
For R-Panel, the fasteners are always placed in the lowest part of the panel whether it’s being used as roofing or siding which ensures a secure attachment to the structure. You will have twice as many screws at the panel ends when compared to the interior of the panel. This helps to prevent high winds from blowing the panels off of the roof.
As a panel becomes deeper, its strength increases. Since R-Panel is deeper than corrugated metal, it is also a stronger panel. This will not make much of a difference on a roof with a solid wood substrate. However, if you have metal siding and you are concerned about dents and people bumping into it then using the stronger panel may be beneficial.
The condition that will be the most relevant is when you have a job that is attached to metal purlins. If the panel has to span from support to support then panel strength becomes critical. A deeper panel can span further and carry a heavier load. The ⅞” Corrugated load chart and the PBR Panel load chart should help you determine which panel is the best fit for your job.
How R-Panel and Corrugated Metal Are Used
Both R-Panel and corrugated are able to be used in a variety of ways (residential or commercial, roofing or siding). However, each panel has a more common way of being used.
Common Applications For Corrugated Metal Panels
Corrugated metal panels are utilized for both roofing and siding. They are also seen more often in residential applications compared to commercial applications.
Common Applications For R-Panel
R-Panels are used frequently in both roofing and siding applications. However, it is used more often as metal siding instead of being applied as metal roofing. In fact, it is the most popular metal siding panel. R Panel is used more often in commercial projects versus residential jobs.
Panel Cost: R Panel v Corrugated
R-Panels generally cost about 10% to 15% less than corrugated. Besides costing less, you will also need to purchase less material since there is no panel side lap as explained in the section below. When you combine both of these factors R-panel will cost 20% to 25% less than corrugated metal on a roofing application and 15% to 20% less on a wall application.
When it comes to ordering material, you will have to buy more corrugated panels than R-Panels for the same project. The reason behind this has to do with how each panel is overlapped.
Panel Side lap
R-Panels are 36” and provide a full 36” of coverage. You pay for what you get. However, corrugated panels will incur a loss of square footage due to the panel side lap.
You will need to overlap the panels two corrugations for roofing and one corrugation for siding. While this seems minor, it can add up depending on the size of the project.
For roofing, you will have to purchase 10% to 12% additional corrugated. For siding, you will need about 6% additional material.
When you purchase R-Panel you are buying a product that is 36” wide and yields 36” of roofing or wall coverage. There is no loss for the panel side lap.
What’s The Best Metal Roofing Panel For Me?
When you are trying to decide which of these panels is best for your project there are the two main factors to consider: the cost of the panels and the look of the panels. If you want a round and wavy looking panel, then corrugated metal is the only choice. However, if you want something that is square or boxy, then you will have lots of choices including R-Panel or PBR Panels.
If you are on a budget and saving money is the top priority than R-Panel would be the better choice. R-Panel is the nicest metal panel for the least amount of money.
Overall, R-Panel is a less expensive, stronger panel when compared to corrugated. This is why you will see corrugated used more often for roofing and R-Panel used more often for siding. R-Panel is also used more often in commercial applications where the appearance of the panel is less important than cost savings and the panel strength.
They are both great products at a good price point. You’ll have to decide which panel has the look and panel features that matches best with your project. Their is a third and more expensive alternative, standing seam metal roofing. Check out this video if you'd like to learn more.