So many variables come into play when choosing the best structure for a multi-storey building. What are the budget constraints? Are there environmental factors to consider? What type of building is being erected? The answers to these questions will inevitably point the contractor to one of the “big three” materials: wood, concrete, or steel.
Each one has its benefits and drawbacks, and if your design is truly optimized for your chosen structure, they can all be cost-effective. You might not realize it, but design can have a greater impact on the cost of a project than the materials themselves!
Read on to explore key differences between the three most popular construction materials, from fire resistance to environmental impact.
In Canada, the cost of steel typically falls between wood and concrete, and the associated return on investment (ROI) is generally quite high. According to a recent study by ArcelorMittal comparing six-storey concrete and steel structures, steel came in 9.6% cheaper than concrete with all factors considered and apple to apple comparison is made.
This low-maintenance material has a longer lifespan than wood, which makes for lasting structures that can be erected in any type of weather. Thanks to lightweight profile of steel components and high strength to weight ratio, foundations for steel buildings are considerably lighter than under concrete structures that can be up to 50% heavier than steel structures. Steel also has an advantage in the event of earthquakes. It offers the highest ductility of all materials and allows resistant building steel structures to bend considerably without breaking. In the event of a fire, steel will not combust, while wood carries a larger risk – in short, its durability is a major selling point!
Steel has recycled content of 93% and a recycling rate of 98%, which makes it the highest of any building framing material. Other products can only be recycled into lower quality products (down-cycled), while steel can be recycled over and over again and remade into new components without any loss of quality (multi-cycled). This makes steel the first and only true “cradle to cradle” building framing material.
Since you can prefabricate steel components, this material is particularly easy to install and requires much less manipulation on-site. Compared to wood and concrete, it provides superior sound insulation, and contrary to popular belief, it’s just as effective for climate control (since all structures need to respect the same energy efficiency standards).
Similarly to steel, concrete boasts high sound and fire ratings, and it is overall quite durable and low-maintenance. However, it cannot be cast in certain weather conditions, making for a shorter construction season: it is unable to set in the winter or in extreme heat. Additionally, while steel is 100% recyclable, concrete can only be reused as aggregate, and it creates lots of CO2 during production.
Given the limited regional availability and the lack of skilled labour required to install it, this material is typically the most expensive of the three – though prices do fluctuate quite a bit from coast to coast. The weight of concrete makes it susceptible to damage in the event of an earthquake, and it is also associated with more costly soil improvement when used on a subpar soil condition.
In our recent case study we compared the building schedule of our Hambro steel building system versus traditional concrete, for a four-story 155,000 square feet (14,400 square meter) senior care residence and we found that the steel structure took 10 weeks less to erect (14 weeks for steel versus 24 weeks for concrete) . This translates into hundreds of thousands of dollars in savings if building revenues and reduced bank interest costs were taken into account due to earlier occupancy of the building.
Traditionally, wood is the lowest-cost material on the market, though it tends to be less durable than steel and concrete. Due to shrinkage, warping, and susceptibility to mold, wood requires more maintenance, and it is more vulnerable to pest infestations due to its organic nature.
In that same vein, construction of wood structures are highly susceptible to adverse weather conditions and must be erected in good weather conditions: if the percentage of moisture in the wood material is too high, the wood will experience too much shrinkage and you will be unable to close up the structure. If you are building in a predictable climate, this should not be an issue, but it can lead to delays and budget overages in less consistent climates.
Compared to steel, wood is often not prefabricated, meaning that most of the components need to be cut and assembled onsite. While labor for wood tends to be more available and less expensive, the additional input can still rack up a large bill. Arguably the largest drawback of wood is the combustion risk and fire protection: on-site, it is prone to fire due to the friction created by tools and the heaters used on the construction job sites.
When there is a fire in a steel or concrete building, the structure does not burn; only the finishes and contents inside the building. Following a fire, steel and concrete buildings can be rehabbed and reused again. The same is not true for combustible wood construction. That is why the All Risk insurance rates for wood buildings are double those for steel buildings. It is much less cost effective to bring the wood structures to the same level of basic code requirement for fire and sound protection.
Environmentally speaking, wood has the lowest carbon footprint, especially if it is harvested sustainably and associated with forest regrowth efforts. However, it is less recyclable than steel, and its availability can be limited if a harvest zone is experiencing a pest infestation or fires.
While some construction materials are fundamentally more available and affordable than others, you can make nearly any project cost-effective with the right design. It is all about working around your chosen material, understanding its strengths and weaknesses, and being ready to explore different options if they better suit your design. If you have not already, we recommend giving steel a fair chance – in many cases, it blends the best of all worlds, and it might just surprise you!
Want to see what your next project could look like if you used a steel structure? Our experts can help you adapt your design, define your budget, and build an optimized schedule that will have your structure delivered on-time with no overspending.