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Quonset and Arch-Type Structures

March 30, 2020

Quonset Arch Building in the agricultural land

In their search for a new building, many of our customers quickly recognize the benefits of a steel building solution. But there are different types of steel buildings, and not all offer the same efficiencies and benefits. There are four main types of steel buildings that can fall under the umbrella of being pre-engineered solutions. These are the Quonset Hut and its arch-type variants, the C-channel Metal building; the traditional Rigid Frame Metal Building system and the Hybrid steel building solution. Each of these steel building solutions has its merits, advantages and disadvantages; and each is better suited for specific functions and applications. We have explored the Rigid Frame and C-channel in great depth in previous blogs, let’s now turn our attention to the Quonset Hut and other arch-type steel structures.

Steel Quonset Hut

Quonsets & Arch-Type Structures

The Quonset Hut was the first pre-engineered steel building which was originally manufactured as a temporary structure used during the World Wars. It consisted of pole arches with sheets of metal cladding lain over top, that were incredibly easy to transport and because of their stack-ability they could be easily assembled, and re-assembled, on the war front.

One feature most appreciated during this time was the ability of the structure to contain and lift when a bomb was detonated inside of it. And of course, because they were entirely made of steel components, the Quonset Hut was fire-resistant.

Tip: The Quonset and all arch-structures, like the C-Channel and Rigid Frame Metal Building Systems are made from 100% steel components. As such, they share an “A”-Fire Rating. Many customers don’t realize that this non-combustibility factor can save significant money on insurance premiums for the life of their pre-engineered steel building.

Arch Metal Structure

The Arch – Strength and Integrity

The Quonset Hut serves many great purposes – and truth be told, I have a bit of a protective affiliation for it, because it was the first steel building I was taught to recognize, and to sell. The most amazing thing about the Quonset, is that the integrity of the entire structure remains entirely dependent on the integrity of each individual arch. And anyone who has traveled to Europe and witnessed the historical architecture there, understands the strength of that arch.

That the arch provides the structural support for the building means that all Quonsets have clear-span interior. As is the case for all pre-engineered steel buildings, columns and posts are not required for structural integrity. This means there is nothing to get in the way of 100% usable interior space.

Quonsets are pre-engineered, requiring conformity to National Building Codes and loadings. This means that like all pre-engineered steel buildings, Quonsets must be custom engineered to withstand the loads and codes of the specific location in which they will be erected. Simply speaking, the gauge of the steel determines the ultimate strength of the structure – the lower the gauge of steel, the thicker and stronger each arch will be.

The arches of a Quonset are deep corrugated galvalume steel, and the corrugation itself provides added structural strength to the overall structure. It also provides the exterior of the building so that it is structure and covering all in one. This is part of the economical design of the Quonset – The surface and structure are one in the same.

Custom engineered steel Quonset hut
Open Quonset steel building

Depending on the width of the structure, several segments are bolted together to form each individual arch and each arch is then bolted to the next arch in sequence. The arches are anchored to a foundation – usually a floating slab. An industrial base plate which connects the arches to the foundation, is arguably one of the most important components in the construction of all Arch-type steel structures. This plate is extremely valuable to line up the arches properly without any torch or twisting.

Tip: If you are buying a Quonset, make sure to include the base plate connector in your overall cost. This important component, is an optional feature that you don’t want to overlook.

The first Quonsets were frequently referred to as dome structures. Their shiny, half-moon shapes adorn many of our Canadian provinces as it quickly became a fantastic solution for agricultural applications, especially in terms of livestock housing, and crop storage. But customers soon understood that there was a significant amount of space that was being lost on the sidewalls of the Quonset. Because of the structural design of the arch, the sides of these original steel structures, are not vertical and this loss of space on the sides of the structure quickly adds up.

Tip: In comparing Arch-type steel buildings with other pre-engineered building systems one very important factor for customers to consider is the height measurement. The height of an Arch building is taken from the center of the highest component – the highest point of the arch. The height of a c-channel or rigid frame instead, is taken at the EAVE HEIGHT (not at the peak) – where the sidewall meets the roof. For example, an arch building with a listed height of 12′ may be comparable to a gable building with a height of 9′, depending on the pitch.

pre-engineered steel building
Quonset Diagram

Structural Security & Aesthetic Appeal

In an effort to deal with this lost space, Quonset manufacturers created several different models of the original arch building.

Quonset Diagram

And although in many of these new designs, the lost space is minimized, there has been a trend away from these arch-type structures for two main reasons: high snow loadings and, aesthetic appeal.

In the last few decades there have been many incidences of unexpectedly high snow fall mixed with heavy rain, in many regions of North America. These unprecedented weather conditions caused structures of all types to collapse. Naturally, the devastation and loss of property evoked significant concern and resulted in the implementation of new and stringent National Building Codes. These new codes in turn, had the effect of limiting the use of large, arch-type structures in many areas, because the gauge of the steel required to pass approval was so thick that it increased the overall building cost dramatically. Quonsets became comparable to other traditional pre-engineered steel building alternatives in terms of price, and were no longer the affordable option for large-scale projects.

Tip: The types of loads and their magnitudes are critically important to the design and construction of any pre-engineered steel building. Both the location of the site where a building will be located, as well as the location and positioning of the building ON THAT site, are extremely important in determining the integrity of any pre-engineered steel structure. If a building is going to be located in an area with obstructions, other buildings or trees for example, then that building must be engineered to withstand the additional snow that may occur as a result of the snow shadow – that is, the redirected snow accumulations that are caused by the positioning of those obstructions, in relation to the steel building. Today, Pre-engineered Steel Building suppliers are very weary of obtaining this vital information from customers. When discussing your project, be certain to share information about your site with your Building Consultant. 

At about the same time that the NBC became more stringent, many municipalities also passed Bylaws prohibiting the use of arch-type structures in commercial and residential areas, based on their aesthetic appeal. Several lobbyist groups took up against the shiny surface of the galvalume arches, saying they looked unconventional, industrial and unattractive in municipal areas with high frequency and residential space.

Since it is generally not recommended to apply paint to the arches of these structures, aesthetic creativity and customization are generally limited to the Endwalls of these metal buildings. Many customers are happy to build their own Endwalls out of wood or steel panels in order to adorn the front of their metal building systems.

Tip: If you are buying a Quonset, make sure to find out if both Endwalls of the structure have been included in your cost summary. Many suppliers consider the Endwall an optional feature and include it at an additional cost to the standard kit.

Another factor for some customers is that Door and Window Openings are typically limited to the Endwalls of the Quonset. Recall that the single most important factor in establishing structural integrity in the arch building, is the arch itself. It follows that placing openings on the sides of the arch requires extensive engineering to ensure integrity – at an increased cost. The limited use of door openings on the sides of the structure has implications for both aesthetics and functionality.

All of these things combined have made arch-type structures applicable to a very specific consumer market: Typically those looking for large structures in areas with little to no snow fall; and those customers who are looking for smaller buildings – up to approximately 35’ in width, for use as Backyard shops and garages. Often these buildings are marketed as do-it-yourself kits and, although it can be tedious and time consuming to bolt together each arch into the next with thousands of bolts, the main challenge for DIY customers is to maintain the alignment of the arches without twisting during the erection process.

Tip: As mentioned previously, make sure to discuss the inclusion of the base plate connector in your building quote. This connector will help to diminish the twisting of the arches during construction. Equally important, if you are considering an Arch-type steel structure, find out if your supplier has included the butyl rubber caulking in your cost summary. Many suppliers consider this caulking an optional feature and include it only at an additional cost to the standard kit. But Butyl rubber caulking applied between the arches during the construction process has been shown to reduce the possibility of water leakage in these buildings. It is extremely difficult to apply effectively after the building has been erected.

Closing Out

There is little doubt that the Quonset Hut and other arch-type structures have provided valuable structural space for many customers.

Once a very affordable steel solution, arch-type structures have suffered in popularity as changes to the National building codes and to municipal bylaws imposed stringent guidelines that restricted their use in areas with high snow loads, and in several residential and commercial zones.

As a result, the Quonset Hut and other arch-type steel structures, have become limited to servicing a very specialized segment of the consumer market. Their increased costing and issues with aesthetics, have inspired customers to look into other types of pre-engineered metal building solutions in order to get the benefits previously sought from the Quonset. Pre-engineered solutions, like the C-channel, are beginning to replace smaller arch-type structures because they offer the same do-it-yourself construction, with a more traditional aesthetic appeal and at a comparable cost. And for larger buildings with wider constitutions, Pre-engineered Rigid Frame steel buildings have become an alternative solution, especially in areas where environmental conditions are of high consideration.

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About the author 

Michelle Keenan

Michelle is one of two owner-operators of Norsteel Buildings, alongside her husband Sean. Michelle has more than two decades of experience in steel building design and construction, and has worked with thousands of customers over the years to make their building dreams come true. Under Michelle's leadership, Norsteel has been recognized as one of the Top 100 Builders in North America 5 years in a row.

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