How does terrain affect my metal building?

By Carport Central   |   Posted In: Carports

18x31x10 Custom carport3

The terrain in which you place your custom metal building has a substantial impact on the design requirements of the building. The stresses that it will be exposed to need to be quantified so that it can be designed and installed in a safe manner and is strong enough to withstand these stresses.

Standard calculations can be done to calculate the wind load that a building will experience. Wind can put stress on a building horizontally causing it to lean over, or to move from its foundations and there can also be a vertical effect causing the building or roof to lift. Variables like wind speed, length and breadth of building, roof design and eave overhang are all used as inputs to calculate wind load.

Buildings are designed to a specific Ultimate Limit State for wind pressure. This means that the strength of the metal components of your building must exceed the stresses that the building will be exposed to through wind. The greater the impact of wind on the building, the thicker will be the metal beams used in the structure and the sheeting of the side and roof panels.

One of the key factors in determining the wind loading on a building is the terrain classification. There are 4 main categories for terrain classification with subdivisions within those categories.

  • Category 1 is a region where there are no obstructions to block the flow of wind i.e. open land or land next to a large body of open water.
  • Category 2 is a region where there are very few obstructions.
  • Category 3 is a region where there are a number of similar size buildings that will affect the flow of wind. Suburban areas fit into this category.
  • Category 4 is a region where there are large numbers of very tall obstructions that will have a direct impact on wind flow. City centers fit into this category.


Carport Installation

Another critical aspect of terrain that affects the stability of a metal building is the level of the land. If there is any slope on the ground on which the building will be installed, this should be leveled out before construction. The reason for this is that the slope will cause one part of the building to experience additional pressure from the weight of the building pushing to that side. This adds significant stress to the structure at that point and causes the building to be vulnerable to any other minor stress that may come along e.g. mild winds or a bump from a car etc.

The design strength of a metal building is very important for the safety of people using the building as well as the protection of your car, RV or stored goods. Your building supplier can help you to evaluate all the stresses that your building may be exposed to and ensure that the design is safe for your environment. Your local council can also help you to verify the terrain classification for your area.


  • Carport Central

    Carport Charlie knows everything (almost) about metal buildings. Carport Charlie loves to show off his knowledge about steel structures and you can benefit of it too.

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