Alternative Roof Types: Corrugated Metal Roofs – Part I

Last week we started a series on alternative types of roofing. The most common types of roofing in Washington DC are the ones we talk about every single week and include low slope single-ply systems such as TPO, EPDM, polyvinyl chloride, modified bitumen, and build-up roofs. 

Built-up roofs are obviously much less common than the other more modern alternatives in this list, but we still see them from time to time. In the past, we’ve also talked extensively about standing seam metal roofs. However, corrugated metal roofs are a bit different than standing seam metal roofs. Today we’re going to take a look at a few different roofs built with corrugated metal panels and explore the differences and comparisons between these and other types of roof systems.

The outline of today’s article follows below. We will talk about item number 1-3 in this article and then in the next article on Friday we’ll talk about him’s number 4-6.

Alternative Roof Types: Corrugated Metal Roofs

  • Comparison Between Corrugated Metal Roofs and Standing Seam Roofs
  • Fire Resistance 
  • Material Options
  1. Required Maintenance
  2. Suitability for Low Slopes  Corrugated metal roofs can be installed on roofs with low slopes, offering versatility in design.
  3. Limitations 
corrugated metal roof
The corrugated panel metal roof in the picture above sits on a light gauge steel purlin system, similar to, yet much lighter than a wooden truss system.

Comparison Between Corrugated Metal Roofs and Standing Seam Roofs

Corrugated metal roofs have a distinctive wavy or ribbed profile. The corrugations are spaced apart, in a repeated series of alternating ridges and grooves across the metal panels. Standing seam roofs, by comparison, are thinner panels with raised seams that run vertically from the eave or rear termination (in the case of flat roofs) to the ridge. These seams are typically standing or raised above the level of the roofing panel, creating a sleek and linear appearance.

lightweight panels
Because the panels are lightweight and have their own rigidity, the spacing is almost wide open and requires much less structural support.

Fire Resistance 

Metal panels and all types of metal roofs are basically unaffected by fire.  At extremely high temperatures structural steels can deform, warp and even melt.  However, these high temperatures are not reached under most conditions and nonetheless steel is non-combustible.   This means that the material itself won’t feed a fire.  That’s important because it won’t ignite and buildings built without wood or combustible materials are way safer from a risk of fire.

gable style roof
The ridge is the highest point of a gable style roof, there the panels stop before that ridge and are covered.

Material Options

In the pictures in this blog, we are showing zinc galvanized steel corrugated roof panels and light gouge steel frame of similar materials.  We also will show more pictures of a structural triangular shaped uncoated steel truss structural support system in the upcoming blog.  

roof band board
The roof band board at the underside of the ridge is just a 16 ga. cold rolled framing member, not a structural tube steel.

The cold rolled elements are much weaker, yet strong enough in some cases to support a lightweight corrugated panel system.

roof with alternating pitches
The picture above shows a separate and different roof with alternating pitches including a valley.

The gutter runs along the valley area instead of being spanned with a metal flashing. Here you can see the gutter is supported by excess metal scraps that are cut to the shape of strapping and attached with rivets instead of screws.

underside of the roof
The picture above shows the underside of the trough gutter.

Upkeep, Care and Maintenance of Washing DC Historic Roofs

It’s worth noting that while many of the historic methods of roofing do not work well in our climate zone, the principles of this type of building design and engineering highlight the fundamental principles of our roof flat and mansard roof design here in Washington DC. Consulting with a roofing professional, like Dupont Roofing, familiar with the specific climate conditions and the building science of roofing in Washington DC is advisable to ensure the roof assembly is appropriately designed and constructed to manage the flow of water, ice damming, capillary action and condensation effectively.

The upkeep, maintenance, and general care of flat and mansard roof systems should be driven by an understanding and passion for historical methodologies, waterproofing principles, engineering and building science. Washington DC, a city built with both vintage charm and contemporary modernities, residential and commercial buildings of substantial value. 

The roofs of these buildings are their defensive shield from the harsh elements of nature. To our clients, as well as all readers of this article and our blog, we emphasize the importance of quality construction and active building maintenance.  Our website includes informative resources you can use to understand and learn about best practices on preservation of your building.  If you are in need of further guidance on the roof and its associated systems for your Washington DC property, we are here to assist, where we can. Simply contact us or complete the webform below and drop us a line and we’ll respond if we can help.

On Key

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