How to budget for a sandwich panel building before comparing contractors’ quotes

In the brief, distinguish a weathertight shell from a building ready for occupation. State who will provide the design, the ground investigation, utility connections and external works. If one contractor includes these items and another supplies just the steel and panels, their prices per square metre are not directly comparable.

Consider a 12 × 24 m rectangle with 4 m high walls. Its floor area is 288 m². Its perimeter is 72 m, so the rectangular wall faces also total 288 m² before deducting openings. Measure the roof slopes, gable triangles and eaves separately and allow for cutting waste. A 288 m² building does not translate into an order for 288 m² of panels.

List the length and quantity of each panel. A door opening reduces the clad area, but the panel layout determines whether offcuts can be reused. Calculate coverage using the effective cover width and agree the billing unit with the supplier. Overall width may include an overlap at the joint.

Here is a worked example, not a quotation. All amounts exclude VAT. Allow roughly €33.56/m² for 600 m² of cladding, or about €20,136 for the panels. Add €3,240 for accessories, €4,629 for installation and €1,389 for transport and equipment. The illustrated scope comes to approximately €29,394; the unit rate and line totals are rounded.

That figure does not cover the entire building. Foundations, structural steel, the floor slab, doors and services are still missing. Give each its own quantity, unit and scope. You can then replace an assumed rate with a supplier’s quote without reworking the estimate. Show the contingency separately instead of burying it in a material price.

To assess savings on insulation, consider the heating hours and target indoor temperature together. In a warehouse where doors open frequently, door design and loading arrangements may weigh heavily. In a workshop the ventilation and occupied work area may matter more. Select the panel on the basis of the calculations, not its nominal thickness alone.

Budget for access to clean walls, inspect the roof and replace damaged panels. A well-detailed plinth, impact protection along forklift routes and a suitable coating can reduce repairs. Avoid assigning a percentage saving without evidence. Ask the contractor to describe the proposed measures and the maintenance tasks the operator will retain.

Haulage costs depend on more than distance. Check pack lengths, site access, turning space, delivery times and unloading arrangements. Where there is too little space to store the whole order, staged deliveries may be necessary. Time them to match installation so that panels do not have to be moved twice.

Agree who pays for vehicle waiting time, an extra day of lifting equipment and protection of materials between stages. An old listing is not evidence of stock: reserve a specific batch and quantity. When extending a working plant, allow for traffic management and the period during which part of the facility must close.

Compare panel types, facing thicknesses, coatings, accessories and installation standards on the same basis. Separate firm prices from assumptions the contractor will confirm only after design work. Ask how extra openings, revised lengths and work arising from the condition of the existing structure will be charged.

Review the estimate line by line. A difference of about €2.31/m² of cladding may matter less than an omitted utility system or a missing paved access road. Allow time to review documents and inspect work before it is covered up. A transparent budget lets you adjust scope deliberately instead of discovering omissions during construction.