There are several popular roof configurations for metal buildings, with pros and cons to each. Considerations include the intended use of the building, cost, suitability for local weather conditions, and your personal preference on style.
Metal Roof Panels
There are two main classes of this structural roofing system: through-fastened and concealed fastened.
Through-Fastened Roofing (screw down)
This roofing type is similar to the wall siding described on our metal building siding page. It is the most used and least expensive metal roofing and benefits from fast and simple installation.
A through-fastened roof panel is one where the roof panels are attached directly to the sub-structure with fasteners (treated screws) that penetrate through the panel sheets and into the roof purlins. After installation, the fastener locks the wall panel's overlapping sections into place and is visible on the panel's outside face. Through-fastened systems are also known as exposed fastener systems.
Through-fastening is typically used for buildings less than 60’ in width (measured in the direction of the roof slope). For larger buildings, stresses resulting from temperature expansion and contraction of exposed metal become more pronounced and more of a risk. As a result of the movement, through-fastened metal roofing panels can wear around the fasteners, leading to leaks.
Pros of Through-fastened roofing
- Most economical
- Ease and speed of installation
Cons of Through-fastened roofing
- Potentially vulnerable to leaking on large buildings
- Not as strong if in wind-prone areas, compared to standing seam panels
- Can be compromised if not installed correctly
The most popular through-fastened panel choice for metal buildings is known as the PBR panel.
PBR Panels: (Purling Bearing Rib)
The PBR metal panel (a type of R panel) is a versatile paneling product that can be used for various agricultural, commercial, industrial, and residential applications. PBR panels are highly customizable to suit any need - from different coatings, color options, and substrates.
PBR panels are special through-fastened roofing panels made of 26-gauge steel. All our suppliers include this panel as part of the standard building kit package (24-gauge is also available as an upgrade option).
PBR panels overlap where the panels meet, providing a larger joint, resulting in better leak protection against wind-driven rain or snow. The greater overlap also protects against snow or wind load and the weight of anyone walking on the roof.
Concealed-Fastened Roof Panels
For buildings wider than 60’ (again, measured in the direction of the roof slope), standing seam roof panels are a popular roofing option. Standing seam roofs are installed on approximately 50% of all new commercial and industrial low-rise metal buildings.
There are no screws on the outside penetrating the panels, giving maximum weather-proofing. The overlap seam is above the roof deck, further enhancing the weather-proofing.
All the attachment is underneath the panel itself, attached to the purlins indirectly utilizing concealed steel clips with movable tabs. The clip bases are fastened to the purlins, while the roofing sheets are rolled around the tabs and can slide with the tabs relative to the clip bases – and the purlins. The result - the panels can expand and contract freely with temperature variation, giving both greater weather-proofing, rigidity, and longevity.
Pros of Standing Seam roofing
- Much better protection against leaks in all areas.
- Better protection against leaks in areas with temperature extremes.
- More visually attractive, with no visible screws.
- Stronger for areas prone to high winds.
- Longer lifespan before needing maintenance.
- No exposed screws that would catch dirt need tightening and potentially cause corrosion.
- A standing seam roof could last a lifetime with no maintenance.
Cons of Standing Seam roofing
- Greater cost. Twice as much or more compared to through-fastened roofs.
- More complex (and longer) installation process.
This roofing system is also referred to as architectural roofing and is better suited for buildings with high aesthetic value, e.g., office, community, and commercial structures.
Insulated Metal Roof Panels
Another panel option worth mentioning is the insulated standing seam roof panel. These panels provide excellent thermal R-values, which contribute to the energy efficiency of the building.
The panels consist of metal skins with a steel surface and an insulating foam core (usually either PIR or PUR foam)
Insulated panels are perfect for commercial, industrial, and institutional industries because they provide an unmatched weathertight seal and service life. They provide fast and simple installation and durable, dependable performance thanks to the most recent composite roof panel construction innovations.
Thermal properties, design flexibility, quick installation time, and great looks are why insulated roof panels are popular on modern commercial metal buildings.
- Superior insulation properties.
- Design flexibility.
- Fast installation times.
- Ideally suited to cold storage facilities due to high R-values.
- Relatively high cost.
- Special equipment is required for installation.
Colour Options for Metal Roofing
Please see our page on metal building colors for details on metal roof color options.
Metal Roof Skylight Panels
Skylights are an excellent way to add natural light to a building while also boosting its energy efficiency. They have improved enormously from the old-school, simple lay-in fiberglass panels that might come to mind.
This free light source could be a worthwhile investment, as you could greatly reduce your lighting costs. Natural lighting tends to increase employee satisfaction and reduce absenteeism. Skylights also enhance the value of your building for a possible future sale.
In metal building systems, skylights are typically produced by substituting translucent fiberglass or polycarbonate panels for the steel roofing panels. Fiberglass panels are the most cost-effective, but polycarbonate panels are often used when something stronger than fiberglass is required. Skylights for metal buildings are also available as insulated skylight panel units, with appropriate seals around the perimeter to prevent water intrusion.
Some manufacturers call these “roof-lights.” Translucent panels can also replace some wall panels to produce “wall-lights.” Skylights are typically positioned on either side of the roof's peak, which is why they are often sold in pairs. The optimal number of skylights will depend on the building size and use.
Modern polycarbonate skylight panels (as distinct from built skylight units) have several key benefits; they:
- Have dramatically greater impact resistance compared to traditional fiberglass panels (almost unbreakable).
- Are weather resistant to wind uplift and snow accumulation.
- Will protect the building against wind-driven rain or hail.
- Are made in a range of shapes to fit with most SM-RIB, PBR, and R metal panels.
- Can be clear, soft white, or a range of colors.
- Won’t yellow and will remain clear better than other glazing options.
- Have the best light transmission while protecting against UV.
- Can handle temperature extremes.
And they are very easy to install on a metal panel roof.
Metal Building Roof Pitch
Roof slope is expressed by the “roof pitch,” which is the number of inches of rise in 12 inches of horizontal length—with a colon between the two numbers. For example, a roof with a pitch of 2:12 (“two in twelve”) means that it rises two inches vertically for every 12 inches horizontal (or two feet for every 12 feet horizontal). The most common standard pitches are 1:12 and 2:12, with 3:12 and 4:12 also available. Roof pitches greater than 5:12 require custom engineering; pitches up to 12:12 can be accommodated.
A standard (most popular) gabled-roof metal building has a roof pitch of 1:12 (nearly flat). The vast majority of large industrial and commercial metal buildings have this pitch of roof. Low-pitched roofs allow you to heat and cool the space more efficiently due to the reduced air volume.
Buildings with higher-pitch roofs utilizing colored metal roofing may provide better architectural appeal (particularly for residential applications).
Snow load is another consideration if your building will be in an area with significant snowfall. A steeper roof pitch will shed snow better.
Choosing a roof pitch
The shape of the roof can be designed based on:
- Budget (a flatter roof is cheaper).
- The amount of clear space required down the middle of the building.
- On weather considerations such as snow load.
- And aesthetics - how the building fits in with surrounding structures.
Why choose a low-pitch roof?
- Easier to walk on and do maintenance.
- It is easier to mount AC units on the roof.
- Improved interior heating and cooling (no high roof cavity to heat/cool).
- Lower installation costs - less steel required for the roof structure.
Why choose a steep pitch roof?
- Increased clear height in the middle of the building, allowing for taller racks and equipment.
- Better architectural appeal.
- Reduced snow loading on the roof structure.
Metal Building Roof Styles
The most popular, easiest roof to install, and most economical roof design option is the gable-style roof.
The gable roof design features two sloping sides that meet at the ridge (top). Many people refer to this as a pitched or peaked roof.
This roof style is practical, cost-effective, and attractive. You can achieve a very low pitch (1:12) or a very high pitch with this roof style (8:12). Most steep pitches are used to counteract heavy snow loads or achieve a certain aesthetic appeal. The adaptability of the gable roof allows it to be employed in any region or climate.
1:12 Gable roof pitch
4:12 Gable roof pitch
Among the key advantages of gable roofs are:
- Good water runoff.
- The style allows high interior clear height and makes loft space possible.
- Simple construction makes it the most economical option.
A standard package for metal buildings will come stock with a low-pitched roofline with a gable frame style. Normally, commercial buyers choose between 1:12 and 4:12 ratios when choosing the pitch of their roofline.
Available roof pitches: 1:12 to 6:12.
Like the gable roof, a hip roof slopes from the sides to the peak. But a gable roof has vertical front and back surfaces, while the hip roof front and back also slope to the peak.
Hip roofs are more difficult and a little more expensive to build than a simple gable roof. There is also less room in that upper building space. But the structure typically performs better in strong winds, so hip roofs are common in hurricane-prone areas.
A gable roof would likely be found on a utilitarian building - storage, warehouse, etc. A hip roof would be more commonly encountered in a public-use building, such as a library, community hall, office, or residence in a wind-prone area.
Key advantages of hip roofs include:
- They perform well in areas prone to high winds and rain.
- Allow for more appealing rooflines to be achieved than gable roofs.
Note: For high wind or storm-prone areas, proper engineering design, construction, and roof system maintenance are critical to prevent major problems.
Unlike other roof style options, hip roof designs require a minimum 3:12 roof pitch. Available roof pitches: 3:12 to 6:12.
Shed Roof (a.k.a. single-slope or single-pitch roof)
A single-slope roof is what it sounds like – a roof with only one slope of a constant pitch. Both sidewalls have a different eave height, and the roof slopes down from the highest eave to the lowest. The slant typically runs toward the back of the building. The pitch angle is determined by the building's intended usage and local climatic conditions.
The single-slope roof is becoming increasingly popular, particularly among those who prefer a more contemporary look. The construction is simple, which results in one of the lowest-cost roof options.
Single-slope roofs are primarily used for low-rise, commercial applications, including strip malls, self-storage complexes, and offices. Typical uses include:
- Storage buildings and self-storage units.
- Single-story warehouses and industrial buildings.
- Office buildings.
- Retail buildings.
- Modern-style garages.
- Contemporary-style homes.
They are a good choice for draining water and directing sliding snow toward the back of the structure, making it safer for those entering the building. The roof pitch is typically rather shallow. The single slope results in slower roof drainage than in a gable roof of the same size and pitch because the gable roof allows drainage in two directions. So metal shed roofs might not be ideal for buildings with long spans located in heavy rain or snow areas.
Overhangs can be added to this roof style to increase its aesthetic appeal (see image below).
Available shed roof pitches: 1/2:12 to 6:12.
Gambrel Roof (Dutch-Barn Style)
The gambrel roof has a familiar classic look. This barn-style roof dates back to the early Dutch settlers in North America. The two-pitch roof is steeper near the sides and shallower in the upper half. The style gives you that much-loved, old-fashioned look and feel, but it is also highly practical. With its two-pitch design, the gambrel roof provides a lot of space within the roof area, where a loft is often nestled.
It’s great for a two-story barn or barn-style home that needs additional storage or an office space above.
The roof's pitch also offers excellent drainage, making it especially suitable for areas with heavy rain or snow.
Upper roof: 2:12 - 3:12
Lower roof: 5:12 - 6:12
Monitor Roof (American Barn Style)
This classic style incorporates a raised (monitor) structure running along the ridge of a double-pitched roof, with its own pitched roof running parallel with the main roof. The signature raised center aisle can run the full length of the building or just partway. This raised area often includes windows, providing extra height, light, and ventilation.
Originally used in horse barns and industrial buildings, these roofs are gaining popularity in barn-style homes (“barndominiums”) because of their additional height and light. The raised center roof can also serve as a storage loft. Farmers can store cattle feed in the center area and could add chutes to make it easier to feed the animals below.
A monitor roofline is also useful for storing overheight vehicles, such as RVs and motor homes, in the middle, with lower doors on either side.
The monitor height and pitch can be engineered to suit your specific requirements.
Roof pitches can be the same for both roof portions or be different to create your own unique look.
Upper roof: 4:12 - 6:12
Lower roof: 3:12 - 5:12
A Quonset Building could be a great choice for those seeking simplicity and a low price point. For generations, Quonset huts have been meeting the needs of the military, industry, and backyard hobbyists seeking safe, dependable, and economical storage space. They are so easy to erect that 75% of Quonset buyers choose to DIY build.
Quonset buildings (a.k.a. arch buildings) can be great for business, industry, modern farms, and families. They are suitable for barns, food or machinery storage, hangars, stables, and even homes.