How wide can a warehouse go without internal columns?

By Johnny · 23 October 2026 · 6 min read

Almost every warehouse enquiry I see opens the same way: “we need 30 metres clear, no columns in the middle.” Sometimes that is genuinely required. Often it is a habit carried over from a layout drawing, and it is costing money that nobody has priced yet.

The reason is that clear span is not a yes-or-no property of a building. It is a dial, and the cost of turning that dial does not rise in a straight line.

What actually drives the cost of clear span

Four things move together when you remove a column:

• The rafter gets deeper. Bending demand over a longer span rises faster than the span itself, so the member does not just get longer, it gets heavier per metre — twice over.
• The column section grows. A taller, deeper column also means a bigger base plate and more anchor bolts.
• The foundation grows. Overturning and uplift at the column base are what the foundation is resisting. Longer span means more of both, and in poor ground this is where the real money appears.
• Transport and erection get harder. Deep members need bigger trailers and bigger cranes. On a site with a narrow access road, this can decide the whole method.

Notice that three of those four are not steel cost at all. That is the part owners miss. The quote goes up, but only a fraction of the increase is the material they think they are paying for.

Where the curve turns

In practical terms, the frame behaves like this:

• Narrow spans are dominated by handling and minimum sections. You are paying for erection, not for steel.
• The middle band is where a simple portal frame is efficient and predictable. Rough drawings and early budgets hold up well here.
• Long spans are where the frame stops being simple. Members become fabricated rather than rolled, splices appear, and the crane used to erect it becomes a cost line of its own.

Two things move that turning point, and they matter more than the span itself:

The building height. A wide, low shed is a different structure from a wide, tall one. Height adds to the column’s effective length and to the wind area it resists.

The wind at the site. This is the single most under-supplied number in enquiries I receive. If you do not know the design wind speed in km/h for your site, you cannot get a comparable price from anyone — each supplier will assume something different, and the cheapest assumption will look like the cheapest building.

When keeping one column saves you real money

If the operation allows a single row of columns, the saving is usually larger than the cost of working around them. Three cases where it is worth arguing for:

• Storage with aisles. If the layout already has racking lines, a column on a rack line frequently costs nothing in usable area.
• Bays you will never drive across. A column that sits at the end of a bay, not in a traffic path, is not in the way.
• Future mezzanine. A column line is a gift if you ever add a floor. Without it, a mezzanine over a long clear span is a separate structure inserted into the building.

The question to ask is not “can we have no columns?” It is “what does the column actually block?” That is a layout question, and it is much cheaper to answer than a structural one.

What to tell a supplier before asking for a price

If you want quotes you can compare, give the same five things to everyone:

1. Clear span, and total length — and whether either can move.
2. Eave height, and the reason for it (a machine, a truck, a stack height).
3. What the roof must carry — nothing, solar, a suspended conveyor, services.
4. Whether a crane is coming, now or later, and what it must lift.
5. Design wind speed in km/h, and the ground condition you expect.

Miss any of these and the prices you receive are not comparable, even if the drawings look identical.

The mistake I see most

Buying the span from the layout drawing and the crane later. A maintenance bay designed without a crane and upgraded afterwards is not an upgrade — the columns, the rail beam and often the foundation all change. It is usually cheaper to build the bay for the crane you might buy in three years than to rebuild it when you do.

The same is true of eave height, and of dock level. These three — span, hook height, dock level — are the decisions that are expensive to revisit. Everything else in a steel warehouse can be adjusted later with reasonable effort.