Building Design & Understanding Quotes

Not too sure about aspect of building design or how to understand your quote letter? Please click the + against each term below for a description and extra information. If you cannot find the information you are looking for, please call 1800 821 033 to be connected with your nearest THE Shed Company outlet. 

The gable end (or end wall) of the building is either end of the building which shows the roof pitch, and the highest point of the building. 

The length of the building is determined by the distance from one gable end to the other gable end. It is measured from outside edge of the end girt to outside edge of the end girt.

The shed span refers to the gable end of the building and indicates the overall width of the building. The span is measured from outside of side girts or inside of wall sheeting. 

The bay sizes of the building are determined by the distance from the centre of one portal to the next. The different bays determine the length of the building; you may have a 9 metre long building made up of 3 bays at 3 metres each.

Our engineering allows a clear span up to 30 metres in non-cyclonic regions, and 24 metres in cyclonic areas (design criteria dependent). Larger clear spans are possible on specialised buildings. The further you span, the bigger the portal frames become.

The height of the building is measured from the base of the column to the top of the eave purlin. Skillion roof sheds will have both a high-side height and low-side height (due to the mono-pitch sloping roof). 

Barn height is determined by two heights; outer wall and inner wall. The inner wall is the main body (tower) of the barn and the outer walls are the enclosed awnings of the barn.

THE Shed Company deploys site specific engineering on all portal frame shed designs. In order to do this a number of criteria specific to your site are considered including wind region, topography, terrain, shielding, importance levels and wind loads. 

Topography is the detailed map of the surface, shapes and features of land. This includes features such as mountains, hills and creeks on a site. Extreme changes in topography can increase the speed of the wind in any given direction.

Terrain consists of any structures and/or vegetation and trees within the building area.

The Importance Level of your building indicates the level of consequence in the event of structure failure. The greater the level, the greater the consequences to a person or surroundings. Your intended building use and Importance Level is an imperative aspect in your building design as it will influence the engineering that is used.

National Construction Code defines four Importance Levels:

Level 1  Buildings with a low degree of hazard to life and other property

Level 2 - (default) Buildings that have not been assigned Levels 1, 3 or 4

Level 3 - Buildings designed to contain a large number of people

Level 4 - Buildings essential to post-disaster recovery or hazardous materials facility 

There are four types of wind regions within Australia:

Region A – Non-cyclonic Area

Region B – “Low risk of cyclone” Area.

Region C – Cyclonic Area

Region D – Severe Cyclonic Area

The Australian Standard 1170 pre-defines wind regions for the country. The wind region has nothing to do with surrounding domain or buildings.

Terrain Category is determined by the surrounding landscape within a certain circumference of the structure. 

Shielding plays an integral part in determining your building’s site design and engineering. It is important to note that only permanent structures provide shielding. Trees and other forms of vegetation do not provide any shielding. 

Wind load is the load on a steel building caused by the wind blowing from any horizontal cardinal direction. There are 8 Cardinal directions on a compass and each cardinal direction can have a different wind speed which will affect the overall wind speed.

Internal pressure is the pressure within a building which is usually caused by external atmospheric conditions. Designers and engineers must take into consideration the resistance of the entire building, including internal pressures. 

The slope or pitch of a surface, such as a roof or gutter.

BMT refers to Base Metal Thickness, which is the thickness of the steel only. BMT is an important aspect of your steel building (check your quote) as it gives you an indication of the thickness and the quality of your steel structure. BMT does not take into consideration the paint or coating it is purely the steel only.

A structure with a greater BMT is more likely to be stronger and of a higher quality than one with a lower BMT. 

Care should be taken when referencing thickness because some suppliers will quote TCT. eg. 0.42mm BMT is the same as 0.47mm TCT.

TCT refers to Total Coated Thickness. This is the thickness of the steel including paint coating.

Care should be taken when referencing thickness because some suppliers will quote TCT. eg. 0.42mm BMT is the same as 0.47mm TCT. 

No, we proudly manufacture our buildings from BlueScope Steel, a brand that delivers reliability and strength to Australian’s year after year. THE Shed Company manufactures in all States and Territories around Australia from over 20 sites. 

A roof pitch is the angle the roof falls from the ridge to the gutter. THE Shed Company offer gable roof pitches of 10°, 15°, 20°, 25° and 30°. Skillion roof pitches of 6° and 12° are also available.

The main tower of the barn and the awnings will have a pitch. The main tower can have a gable or skillion roof. Typically the awnings will have symmetrical pitches, however these can be different if required. 

Newsletter Sign-Up

Sign up to receive product information, launches, offers and news.