It may not be a well-known fact in the debate surrounding green and sustainable construction that steel is one of the most environmentally friendly materials for use in the building and fabrication process. National and international legislation (such as the new Paris climate change accord) have increased the pressure for low carbon construction. Luckily, steel has a number of in-built cost and environmental advantages which make it a huge asset in the construction industry’s move towards a more sustainable future.
Steel is one of the best reliable and advantageous material for most new architectural or building products. For example steel accounts for almost 70% of the non-residential building market. Steel is often used as a framing material because of its cost-effectiveness, its durability and its sustainability.
Steel reduces labour and shipping costs, and can further simplify the foundations of a building’s foundations and structural support systems. Steel foundations can also save your project time and money. Steel is also highly versatile, which is why our experience with structural metalwork makes us so highly sought after.
For every client we work with, there are a series of key questions and decisions that need to be made throughout the design process. These questions will usually encompass budget, materials, frame solutions and overall time constraints.
Getting your estimates right
Your choice of structural frame and frame material, will need to be made very early on the in the design process. If there are any significant changes to the frame material, then this will have costly implications further down the line, potentially adding to the cost of the project further down the line. At this stage, there are some other considerations to take into account.
• Comparing and contrasting different structural options, considering the impact the frame might have on other elements, e.g. sub-structures, cladding.
• Be ready to undertake more detailed cost planning as more information becomes available.
• When costing, make room for elements which may not yet be quantifiable. These include how the steel frame will actually be constructed when it is on site, making allowances for connections and fittings and the requisite fire protection materials.
What factors affect initial estimates?
Function and facilities
The proposed design of a structure, space or building will affect the design of a frame, including its weight, the floor-to-floor heights and the steel intensity.
Different spaces will mean different grid and loading requirements, which will in turn affect the construction and assembly of any steel structure.
When planning a new build, there will need to be a clear understanding of the ultimate function of a building, e.g. residential, commercial, educational, healthcare.
For example, an open plan office would require fewer columns, but longer spanning beams and heavier steel sections. It would also require further decisions and costings to be made for potential additional structures such as mezzanines and staircases.
Some buildings may have specialised requirements or characteristics which may affect the design of any steel construction or frame. These can include historic facades or pre-existing structures, poor ground conditions, or complex structural solutions. The height of a building will also cause variations to the overall cost of the project.
Working in built up areas can also restrict working hours, deliveries and uses of cranes, which can also further cost further time and money in the long-term.
The cost of raw materials and material prices will need to be taken into account at the initial costing stage.
Concept design and development
Once the initial costings and estimates have been made, the structures of both the building frames and floors need to be reviewed at concept design stage. The impact of structural parts on the other building elements needs to be taken into account.
Your building frame will also have an impact on foundations and cladding costs.
By now, your building project will have a target budget, and the various building elements can be realistically costed.
By now, you will ideally be able to quantify:
• The types of steel frame being used and its design.
• Connections and fittings.
• Erections costs.
• Fire protection.
Frame design and structural products
Each architectural steel frame design for a new building will be different, which means that the structural products will be different too. Universal beams and columns are the most commonly used structural architectural steel products, with built up tresses being used for long spans, and fabricated plate girders used to support heavy loads.
The size and weight of the architectural steel members will be determined as followed by the dead load (the weight of the building itself), live loads (loads imposed on the building during its use) and wind load.
The specific building configuration will in turn affect the volume of steel used for your project.
Don’t make the mistake of thinking that the structural frame with the minimal tonnage will automatically be the cheapest. The overall weight of a steel frame is determined by the components of that frame. This means that the rate per tonne is higher in more complex frame designs and connections.
The availability of a frame can also be a consideration for potential cost projections. More popular or readily used steel products will often be more highly sought after.
Connections and fittings
Your costing will need to take into account extra fittings and connections, as this will increase the overall weight and the frame cost. Connections and fittings will add 5-10% to the overall frame cost.
Erection of a steel frame will also contribute towards the total frame cost. This means that, the quicker a frame is to assemble, the cheaper it will be.
For example, repetitive structures will save money during fabrication, whilst short-span frames will cost more because it will require more columns and beams.
The fire resistance of your steel product needs to be a key consideration during the costing of your product. Your steel structure needs to meet the required fire resistant period to allow for safe evacuation from the building. Fire protection is another cost which will spiral if not given the proper consideration further down the line.
Conclusion: plan, test, collaborate
When planning the configuration of your steel structure, choosing the right frame and material is vital. In order to ensure that any project is adequately planned and costed, the following factors must be taken into account.
• Building function
• Site constraints
• Procurement and supply chain.
• Health and safety.
• Construction methodology
These factors must remain a factor beyond the initial costing stage and into the design stage. The initial design must be tested against the finished product as it begins to take shape. Collaboration with contractors and other parties within your supply chain are vital when working with architectural steel, and for ensuring your project is as cost-effective as possible.