Prefab metal or pre-engineered buildings are structures constructed using prefabricated steel components. They are built off-site in a factory and then shipped to the construction site for quick and easy assembly.

, How Do Prefab Metal Buildings Work?, Days of a Domestic Dad

Prefab metal buildings have become very popular recently because of their speed of construction, durability, and cost-effectiveness. They’re widely used in warehouses, workshops, garages, agricultural buildings, and commercial spaces. But how do prefab metal buildings work?

Below, we’ll cover everything you need to know.

Primary Structural Frames

This is the backbone of the building, responsible for carrying the weight of the entire structure and any contents it holds. It comprises rigid steel columns, which are vertical steel posts that transfer the building’s weight down to the foundation. It also comprises beams, horizontal steel members that span between columns, supporting the roof and walls. Columns and beams are attached using flanges.

Secondary Components

The primary structure forms the skeleton, but the secondary components flesh it out and make it a complete building. These secondary parts are crucial to creating a functional and weatherproof structure.

Girts are horizontal members that span between columns and support wall panels. Imagine them as ribs for walls. Purlins are similar to girts but for the roof. They run between beams and trusses, supporting roof panels and distributing weight evenly.

Eave struts are located where the roof meets the sidewalls. These provide a connection point and contribute to a smooth transition between the ceiling and the wall. Bracing is a diagonal steel element that provides stability against wind loads and lateral forces. Depending on the building design, these can be X-braces, knee braces, or other configurations.

Sheeting and Insulation

Sheeting is the secondary weather barrier behind exterior cladding. It protects against wind, rain, and even air infiltration. Insulation is thermal control, but combined, it creates a robust, weatherproof, temperature-controlled envelope. The sheets are usually colour-coated or galvanized for aesthetics.


Accessories are all non-structural components of a prefab building. They include doors, windows, louvres, liners, vents, skylights, ridges, gutters, and downspouts.

Prefab Building Process

Prefab metal buildings offer a streamlined construction process compared to traditional methods. This is how it works.

Contact a Prefab Building Supplier

The first step in the prefab building process is to find a reputable company to work with. You can find one through recommendations from friends or online reviews. Discuss your needs with a supplier who can guide you through design options and provide quotes.

Drawings and Design

If you agree, the supplier will create a building plan based on your provided information. You must carefully analyze the design to ensure it’s precisely what you want. Be aware of dimensions, layout, features, and customization.


You may need building permits from your local building department to allow you to proceed with the project. The permit required will depend on your locality, but such a project in Canada will surely need one. The building department will also conduct inspections at various stages to ensure compliance with local building codes.


Once the design is agreed upon and permits are given, the specifications will be forwarded to the prefabrication facility. Engineers will translate the design into detailed manufacturing instructions for each component.

A structural frame is typically made of cold-formed, high-strength steel. Steel grade and thickness depend on building size and intended load. Wall and roof panels can be made from various materials, such as steel, aluminum, or insulated metal panels (IMPs), depending on desired aesthetics, insulation needs, and budget.

Prefabrication relies heavily on computer-aided manufacturing (CAM) software. It takes digital building plans and translates them into precise instructions for automated machinery. The automated cutting machines then cut the steel sheets into the needed shapes. Depending on the complexity and size of the building, it might take 6 to 8 weeks to complete.

Site Preparation

This step is one of the most critical tasks in the process. You must ensure the site has been prepared as instructed by the supplier. It may involve clearing the area, levelling the ground, pouring a concrete foundation, or installing a gravel pad. Ensure proper drainage is established around the perimeter.

Delivery and Assembling of the Components

Once the prefabrication is complete, the prefabricated components will be delivered to the construction site. Have a reputable construction company on site to erect the building. They’ll assemble the steel frame, install the wall and roof panels, and accessories. Ensure they follow all instructions given by the supplier to ensure the building lasts long enough.

, How Do Prefab Metal Buildings Work?, Days of a Domestic Dad