Panel quotations are compared on the price per square metre, and the comparison usually ends there. The total cost of an envelope to a building has four parts, and the price per square metre is only one of them.
1. The panel itself
What sets the price does not change from product to product:
| Item | Effect on price |
|---|---|
| Core type | Rock wool is heavier and dearer than polyurethane |
| Insulation thickness | The quantity of material rises directly |
| Steel thickness and coating | PVDF and plastisol sit above standard polyester |
| Colour | Custom RAL colours require a separate production run |
| Panel length and quantity | Waste and production planning show in the price |
The last row of that table is the one most often skipped. Panels ordered cut to the project generate less waste than standard lengths cut on site, and waste is money.
2. Installation labour
A panel arrives finished from the factory; the work on site is lifting, aligning and fixing. Because one-piece lengths reach 15.5 metres, the number of joints falls and the number of installation steps with it.
The cover width is 1000 mm. How many panels will arrive and how many vehicles will be loaded is known before the order, from the panel area calculator and the loading quantities calculator; both feed the labour and transport plan.
3. The difference in the structure
As the envelope gets lighter, the system carrying it gets smaller. Polyurethane core density is 38-40 kg/m³ and rock wool 90-130 kg/m³; on the same surface, the weight difference between the two shows in the purlin section and the steel tonnage.
This item does not appear in the panel quotation; it appears in the structural design. How many kilos of envelope will be carried is read from the panel weight calculator.
4. Energy
In a heated or cooled building, the heat leaving through the envelope returns as a bill every year. The thermal conductivity of a polyurethane core is 0.022 W/mK and of rock wool 0.045 W/mK; the same insulation value is met at roughly half the section in polyurethane.
The cost of going up one step in thickness is paid once and returned over the life of the building. The annual value of that difference is not estimated: the heat loss and savings calculator gives the annual difference and the payback period using your own unit price.
How to read a cheap quotation
The difference between two quotations usually sits not in the name of the panel but between the lines. The places to look:
- What is the steel thickness, and is it the same on both faces
- Is the core density declared
- Which value is the insulation thickness, and has it been confused with the total panel thickness
- Which core is the fire class given for, and is there a report
- Does the load table belong to this product
When all five match, the prices can be compared. If even one differs, what is being compared is not the same product.
Where the cost decision is made
The total cost of a panel is decided at the design table, not at the purchasing table. Once the thickness, the core and the coating are chosen, all four items are largely fixed; what is left to negotiate is a small part of the first one.