When you ask what a hangar costs, you are really asking what the steel weighs. Material is the largest item, and every design decision — span, height, loads — ends up expressed in tonnes. What misleads buyers most is comparing prices for different weights. This article gives you real figures from delivered projects, and what to ask before you sign.
Note: The weights given here come from projects we delivered, with their own dimensions and conditions, and are not a reference for another project. Every project needs a structural calculation signed by a structural engineer under the building code in force at its location.
1. Why does structural weight matter to you?
Because it is what you actually pay for. Steel is bought by the tonne, and the price per tonne is well known and does not vary much between suppliers. The real difference between two quotations is not the price per tonne — it is the number of tonnes.
Hence the paradox: a cheaper quotation may simply mean a lighter structure. That is either smarter design or loads reduced below reality. The first deserves credit; the second deserves a question.
Weight also determines things buyers rarely think about: foundation size, the crane capacity needed for erection, fabrication time, and transport cost. Ten tonnes more means bigger footings, a stronger crane, and extra days on site.
2. What does a real 30-metre-span hangar weigh?
This is a figure from a project we delivered, not a generic table:
From our projects: the Sham View sales hall — 1,200 m² (30 × 40 m), 30 m clear span, 5 m eaves height, no overhead crane.
Structural steel: 49 tonnes in the design study, 42 tonnes as built.
Simple arithmetic: 42 tonnes over 1,200 m² gives 35 kg of steel per square metre of plan area. At the design-study weight it is 41 kg/m².
For span comparison, these are dimensions from other projects we delivered: an industrial warehouse at a 37 m span and 9 m clear height over 2,000 m², and the equestrian hall at a 40 m span over a 132 m length and 5,000 m². A wider span raises the density per square metre, because bending moment in the frame grows faster than the span itself.
3. What drives weight up, and what brings it down?
Up: a wider clear span (the dominant factor), higher eaves, higher snow or wind loads, an overhead crane, wider frame spacing, and a shallower roof pitch.
Down, legitimately: tapered sections that put steel only where the moment is, trusses instead of solid frames at large spans, calculated rather than arbitrary frame spacing, and considered bracing.
Down, illegitimately: adopting load values below reality, cutting bracing members, or reducing section thickness without calculation. All three look like savings in the quotation and show up on site as deflection, vibration, or worse.
This is why the price alone is not enough. Ask for the weight, then ask which load values produced it.
4. How do you compare steel density between quotations?
Divide total weight by plan area to get kg/m². That figure makes two quotations of different sizes comparable.
But be careful: density rises with span by nature. Comparing a 15 m span hangar with a 40 m one on density alone is a broken comparison. Compare at the same span, or ask each supplier to state the span alongside the weight.
When two quotations differ sharply in density at the same span, it is one of three things: different load values, a different structural system, or one of them has not been calculated yet. Ask which.
5. When is a low weight a warning sign?
When nothing explains it. A lighter structure is the result of better design — and better design leaves visible traces: tapered sections, a truss system, calculated frame spacing. If the weight is lower while the system and the loads are the same, the difference came from somewhere.
The most dangerous thing to be quietly reduced is the bracing system. Bracing does not show in photographs and quotations rarely itemise it, and its weight is relatively small — yet it is what prevents lateral collapse. Cutting it saves a few tonnes and buys a large risk.
The working rule: a low weight without an engineering explanation is a question, not a bargain.
6. What should you ask a supplier about weight?
Four questions reveal more than the price does:
- What is the structural weight in tonnes? — asking for the figure before signing is a right, not a favour.
- Which load values was it calculated on? — design wind speed, snow load, seismic loads.
- Is the weight from a structural study or a preliminary estimate? — the difference is real, and we cover it in a separate article.
- Does it include bracing, purlins and connections? — some quotations state frame weight only.
Whoever answers all four with a written figure has done the calculation. Whoever answers "it depends on the project" has not.
- Structural weight
- Steel density
- Hangar cost
- Comparing quotations
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Read next
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