Which prefabricated hall do you need — and what the quotation must state

The first conversation about a hall almost always starts off wrong. The investor asks “how much does a hall of 1,000 square metres cost”, and that is a question to which no honest answer exists — because the same square metre can cost seventy or five hundred euros, depending on what is in it. This text is therefore put together the other way round: from what you know about your business towards what has to be stated in the quotation. By the end you will know what to ask for, what to compare and where quotations stop being comparable.

First the use, only then the floor area

The use determines almost everything downstream: the span, the height, the thickness of the building envelope, the fire protection requirements and whether there will be a crane in the hall. The floor area is actually the least important figure — two halls of a thousand square metres, one a warehouse and one a production plant with a crane, differ in price more than a warehouse of one thousand and a warehouse of two thousand square metres.

Two figures from that selector are worth remembering before you call anyone. The span is the width that the structure bridges without a column down the middle — and that is the most expensive parameter in the whole hall, because the moment in the frame grows faster than the span itself. If your operation can tolerate a row of columns down the middle, that is the single largest saving there is. The clear height is the height to the lowest obstruction, not to the ridge — and that is where mistakes are most often made, because it is measured wrongly and only comes to light when the forklift does not fit through.

Prefabricated or conventional: where the real difference lies

The advantage of a prefabricated steel hall does not lie in steel being cheaper than concrete — but in the fact that fabrication and the building site run at the same time. While the excavation and the concreting of the foundations are going on at the site, the structure is already being cut, drilled and welded in the plant. When the foundations have cured, the structure arrives finished and is erected in weeks, not months. That parallel working is the reason a prefabricated hall gains time, and it is an advantage that conventional construction structurally cannot have.

The second real advantage is predictability. A structure made in the plant, on a machine, with measurement under controlled conditions, has tighter tolerances than what is executed in rain and mud. The third is the possibility of extension: a prefabricated hall is lengthened by adding frames, which is far simpler than breaking through a reinforced-concrete wall.

It is fair to say as well where a prefabricated hall has no advantage. If you need massive walls because of noise, if the building is small and irregular, or if the requirement on fire resistance is such that the steel needs extensive protection — the calculation changes. In a fire steel loses load capacity faster than concrete and is therefore protected, and that protection is paid for.

Why two quotations for the same hall are not comparable

This is the place where investors lose the most money — not on a bad price, but on the comparison of two quotations that do not cover the same thing. Before you compare figures, check whether each of them covers these nine items. If a quotation says nothing about one of them, that item is not free — someone else simply has to pay for it later.

Everything else is a variation on those nine. When you receive two quotations with a difference of thirty per cent, in nine cases out of ten the difference is not in the margin but in the fact that one quotation does not include something. So ask for each to be broken down item by item — and not a single figure per square metre.

The building envelope: where a hall really differs

The skeleton of a hall is a relatively standard product. What distinguishes a pleasant hall from one in which the goods go mouldy is the building envelope — the roof and the walls. The basic division is simple: if the space is heated, sandwich panels are used; if it is not heated, trapezoidal sheet is enough, but almost always with an anti-condensation fleece.

The thickness of the panel is not a question of taste but of regulation and calculation — we have written about that in a separate guide to thicknesses and U-values. If the hall is not heated, it is crucial to understand condensation: an unheated hall with a metal roof and no fleece will drip, and that is not a defect of execution but physics, explained in the text on roof sweat. And if you heat the hall and think you have dealt with the moisture by doing so — you have not; a heated hall full of people or livestock produces dozens of litres of vapour a day, which we take apart in the article on condensation in a hall.

Six facts and you have a serious quotation

You do not need a design in order to get a serious budget quotation. You need these six facts — with them any serious supplier can calculate, and without them you get a figure per square metre that means nothing. For a binding quotation with the tonnage, the execution class and a price by items a design is needed after all: the loads, the ground and the fire requirements go into the calculation, and they cannot be read off from the dimensions.

The whole road from that enquiry to the occupancy permit — nine phases, realistic timescales and where the waiting happens — we have set out in the guide to prefabricated halls, and if you are interested in what happens underneath — how a column is sized and why anchors have tolerances in millimetres — that is in the article on columns and anchoring.

Once you know the span, the next question is what girder goes over it — a lattice or a solid-web girder — and before signing it is worth adding up what is written in no quotation at all: the utility and water contribution and the power connection.

Modeco makes steel structures and prefabricated halls from its own production in Đakovo, with delivery throughout Croatia and the EU. If you have those six facts from above, we can start from them — take a look at the prefabricated halls or send an enquiry.