The Difference Between Conventional and Structurally Engineered Buildings

Everything we do these days is fast. We can order our groceries before we leave work and have them ready to be loaded into our car on the way home. Need clothes, electronics, even furniture? Spend a few minutes online, click a button, and within a day or two the item is waiting at your door. But when it comes to building construction, we don’t tend to think in terms of fast.

But here’s an interesting comparison. The Sears Tower, a conventional building using traditional planning methods, construction techniques, and material usage, was built in just over three years. On the other hand, San Francisco-based 3D-printing startup, Apis Cor, demonstrated it could 3D-print concrete walls for a small house in less than 24 hours. While there is a major difference between a 1,700 foot skyscraper and a small house, the comparison demonstrates how technology has dramatically reduced build time and increased efficiency.

Enter structurally engineered buildings (also known as pre-engineered buildings). This form of construction, popularized by the use of World War II Quonset huts and airplane hangers, uses computer programming to design buildings often made of steel (although concrete is another popular form) that can be manufactured and sent to a build site ready to be assembled. The difference? Compared to traditional buildings, pre-engineered buildings can be constructed up to 50% faster. And if you’re thinking that pre-engineered means one-story warehouse style structures, consider that the Broad Group recently constructed a 30-story hotel in China from prefabricated steel materials and completed the project in just 15 days!

Comparing Methods 

Planning: Conventional buildings are individually planned by architects and require a long process of edits and approvals to complete. Deletions and additions to existing plans further slow the process by requiring new designs to be drawn up. Structurally engineered buildings are designed using computer software and changes are included in software mockups before the manufacturing process ever begins.

Time: Traditional building methods use materials from various sources and delivery of these materials can take 20-26 weeks, which means a lot of lost labor time while you wait for arrival. Pre-engineered materials are produced and bundled at the manufacturer so that all materials can be shipped together to arrive on site ready for construction

Ease of Construction: Conventional buildings, particularly those using traditional steel construction, require specialized labor forces and onsite modifications to materials that take time and cost money. Structurally engineered buildings are delivered ready to be assembled, including fasteners. This requires a smaller, less specialized labor force that can construct the building much faster. Furthermore, less subcontracting is needed so there is less variation in labor that creates unpredictable results.

Foundation Costs: With traditional methods, it is harder to estimate the overall weight of the structure and so foundation requirements are often overestimated to stay within safe limits. This increases construction costs. Because pre-engineered buildings are completely designed on software before construction ever begins, accurate measurements of load can be calculated so that foundations are exactly aligned with safety requirements.

Expansion: Modifications to conventional buildings require essentially starting from scratch with new sets of plans, permitting, etc., whereas structurally engineered buildings are easily modified using modular elements for which there are usually engineer-stamped documents that speed up the permitting process.

Sustainability: Traditional methods create more waste products, have more impact on the surrounding environment of a site, require more movement in and out of the site, and use more heavy machinery for longer durations. Pre-engineered buildings require one delivery to the site, produce little to no onsite debris, and can be constructed faster thus using less machine time and disrupting the local community for a shorter span.

A New Way of Building 

Structurally engineered buildings now offer the durability that was once only the purview of traditional methods. The steel from which they are constructed can last 50 years or more if maintained properly and can withstand seismic forces, high winds, and fire, making them ideal for today’s commercial design. With the help of software design and the combination of modular elements, they are no longer the single-story boxes of the past but can be shaped into a myriad of architecturally compelling designs.