Structural steel estimating controls costs by accurately analysing the amount of material, fabrication labour, and erection before bidding. Fabrication and erection usually comprise up to 70% of the steel package cost; therefore, a precise estimation of these components has a greater impact on an estimator's profit margins than material cost does alone.

What Are Structural Steel Estimating Services?

Structural steel estimating services involve determining quantities, material costs, and labour required for manufacturing and assembling steel components. They generally refer to the process of converting structural drawings into a bill of quantities. Estimators turn their figures into a breakdown of costs for steel weight, connections, and site labour.

The estimating teams usually work according to the American Institute of Steel Construction guidelines. These guidelines standardise the design, construction, and fabrication of structural steel. Many estimators also use the American Welding Society specifications, particularly for fabrication, where welders’ costs are a significant part of the budget.

How Are Steel Material Calculations Performed?

Accurate steel material calculations remove the risks of over-ordering and under-scoping the labour. This calculation helps estimators determine total material weight by multiplying by the steel beam's per-foot weight. 

For example, a W12x26 steel beam, which is 20 feet long, weighs 26 lbs./ft. × 20 ft = 520 lbs

The above calculation uses the multiplication of the length by the steel beam per foot. This provides the total weight of materials needed for a project. 

The common method of valuation at the project level is to multiply the total steel weight in tons by the price per pound. Additionally, there is a need to add fabrication and erection costs. 

An example of which is illustrated below: 500 tons of steel priced at $3 per pound will result in (500 tons x 2000 lbs) x $3 = $3,000,000. Additionally, there is a need to add fabrication and erection costs. The expenses incurred in the process vary between $2.00 and $4.50 per pound based on installation costs and geographical location. In simpler terms, structures such as warehouses cost less than more complex ones.

What Drives Fabrication Cost Planning?

Connection type has the biggest impact on the fabrication cost planning. Moment connections are 3-4 times more expensive than shear connections. This is due to the use of heavier flange plates and full penetration welds.

Material is less than one-third of the cost of a building's framing system fabrication and erection make up the other two-thirds. The frame itself represents only about 12% of a project's total cost. This will impact the overall budget: a 5% increase in material price adds less than one-fifth of one per cent to the total project cost. 

How Does Installation Cost Estimation Work?

Installation cost estimation follows a repeatable sequence:

1. Review drawing for member size, type of connections, and erection sequence.

2. Calculate manpower-hours by types of connections because moment connections require more field welding and inspection.

3. Use current unit prices from fabricators and labour sources.

4. Consider the jobsite logistics, including crane availability and erection sequencing.

5. Add lead time because mill rolling schedules are 8-12 weeks for structural steel. In addition, fabrication adds 4–8 weeks, and overall delivery is 12-20 weeks.

What Happens When Estimates Are Inaccurate?

Small mistakes made at huge scales lead to significant losses. A report by the Association for the Advancement of Cost Engineering International indicates that a quantity or unit price error of +3% to +15% on the high side is frequent, causing project costs to exceed the acceptable range. Therefore, having the wrong price for a particular element can significantly erode or eliminate profit margins. 

How Can Contractors Improve Estimating Accuracy?

Manual takeoff for a typical mid-size structural package takes 4-8 hours, and far more for complex projects. By delegating it to the professionals at Universe Estimating, you can rest easy knowing your steel estimating has been completed by experts, because:

• Every drawing sheet is cross-referenced with all accompanying connection sheets to prevent omissions.

• Any questionable dimensions are verified with the engineer of record.

• Current unit prices from suppliers are used, not an outdated price list.

• Calculations are checked for conformity to AISC and relevant welding standards.

Bottom Line

Ultimately, structural steel estimating is the cornerstone of cost management in any modern construction field. This is because most of the costs, in this case, are incurred from fabrication and installation. This makes up approximately 70% of the entire steel cost package. Therefore, coming up with estimations based only on the materials’ weight risks eroding an organisation's profit margins.