Wide Span Buildings

What is a Wide Span Building?

When we describe a Wide Span building typically we are talking about one roof spanning a wide distance. Wide Span buildings can be broken down to two types of designs; they can be categorized as either a supported roof design or clear span roof design. Clear Span meaning the roof is self supported in design and is not supported in any way through the structure by a post or similar, there by creating a clear open space. The supported roof design building is as described in that it has support posts or walls internally assisting in holding up the roof.

Wide Span, Clear Span or Both?
There are pros and cons for both supported roof buildings and clear span structures, many factors are taken into consideration before deciding on how the building will be supported.

The Wide-Clear Span building has multiple advantages for the user, now and as a future proofing strategy for a developer or owner/builder etc as the floor space is unencumbered by roof support posts, the obvious advantages are for multiple uses where the tenant/owner occupier of the space needs an open space in which to operate their business.

The supported roof Wide Span building may limit usability as there will be at least one line of posts down the center of the building or there may be multiple posts throughout helping hold up the roof depending on the design parameters, of course it may not be a limitation it may be an advantage. In the case of a supermarket or distribution warehouse or a courier company for example, the support posts can be or may be used to locate storage racking systems or similar and there by eliminating the post from view while not limiting the wide span advantage of having the entire business “under one roof”.

Sometimes the choice of whether you go clear span or supported span comes down to needs and wants juxtaposed with costs and practicability. A simple explanation could be; a self supported roof, or clear span building must hold itself up by itself through the strength of the structure, from footings through the portal frames to the purlins and girts. Therefore, the structure must be strong enough in size to support it own weight including environmental loadings such as wind and snow etc. In addition the footings where the portals are housed must be of sufficient strength to hold up a self supported or Clear Span roof, meaning the use of large mass concrete and reinforced pads or piles to provide the necessary loading.

A supported roof in contrast, has the effect of halving or reducing the need or support strength by placing a post/s in the center of or throughout the building to assist in holding the roof up. The net effect is the supported roof will be less expensive as there will be less steel needed to hold up the building and less footing size etc because we have positioned support post/s in the center of each portal frame spreading the weight load. The initial gain is the cost advantage, as the amount of steel/concrete etc needed to build a supported roof building will be less than a self supported roof or clear span building, generally speaking.

An example of which design to use can be seen when examining the Agrissentials case study. The need was a 50 meter wide span building to operate the business, at first the option of two 25 meter span buildings side by side with one support post in the center was considered however, as you can seen in the case study, the need for large trucks and materials handling equipment to operate within the building meant support posts would restrict the usability of the space considerably. While it was cheaper to build with two smaller span buildings side by side the overall cost to productivity made the decision to have a supported roof or Clear Wide Span building design a simple one to make.

Engineering Considerations with Wide Span Buildings.
Lightweight steel or cold formed steel has revolutionized the “shed” market with its many attractive attributes including, speed of erection, the ability to span wide spaces and its cost advantage when compared to traditional wooden buildings. However, all good things come with limitations and there is a price to pay. In this case lightweight steel is limited by engineering mathematics namely Newton’s Law, the strength of the product means it cannot clear span more than 34 meters without being supported, the price to pay is, if you want to span larger distances you must use structural steel or hot rolled steel or use a roof support post or wall. The need to span wide distances continues to grow as more and more businesses expand and need bigger wider spaces in which to operate.

While this is an overview of wide span buildings and types of materials there is much to take into consideration when deciding on what sort of building you build, the first step is to talk to us and we will help make the decision clearer and hopefully easier to make.

Some Applications for Wide Span buildings:

  • Enclosed Equestrian Arenas
  • Aircraft Hangers
  • Warehouse buildings
  • Storage Buildings
  • Agricultural buildings
  • Recreational Buildings
  • Retail Buildings
  • Self storage buildings
  • Commercial buildings
  • Gymnasiums
  • Manufacturing Buildings
  • Office Buildings
  • Workshops
  • Distribution warehouses