Estimating sandwich panel installation costs when work is split into stages

Separate walls and roof if they require different access or equipment. Establish who is responsible for unloading and moving the panels to the installation zone. Check whether the price includes auxiliary components and materials consumed during the work. Fasteners are sometimes supplied by the client, but are sometimes included in the contractor’s offer. Do not count them twice.

Some costs arise regardless of the number of panels. The crew must travel, prepare the site and set up the equipment. A lift has transport costs and a minimum rental period. For a small extension, these items are spread over a small area.

If you divide the works into three visits, do not assume you will pay the same as for one continuous stage. Equipment may need to return and the zone may need to be prepared again. On the other hand, phasing sometimes allows the building to remain in operation. It is worth comparing the surcharge for organisation with the cost of fully taking the facility out of use.

The following figures are purely an arithmetic example, not a current price list. Assume 180 m² of panels and an assumed labour rate of €12.73/m². This gives €2,291.40. Add to this €555.48 for equipment and €370.32 for additional activities. The total model cost is €3,217.20 before any applicable tax.

Divided by 180 m², this gives approximately €17.87/m² for the entire assumed scope. If the second stage requires another equipment visit at an assumed €277.74, the total rises to €3,494.94. The model does not determine a market rate. It shows why comparing only €12.73/m² can conceal a significant part of the expenditure.

The length and weight of the panels, the installation height and the possibility of equipment access are significant. Dense development can make manoeuvring a long load difficult. Numerous windows, corners and passages increase the number of cuts and details. The façade area alone does not describe this labour intensity.

Before the quote, show the contractor the site plan and the layout of openings. For refurbishment, describe the condition of the old covering and the scope of dismantling. If work must be carried out at specific hours, state this straight away. Access restrictions established only after signing the contract often lead to disputes over additional costs.

Establish whether the basis for settlement is the area of panels laid, the wall area or the quantity of material delivered. These values may differ. Window openings take up space, but finishing them requires work. The method of deducting openings should therefore be set out in the quote.

Flashings can be settled separately by length, by piece or at an agreed lump sum. It is important that the scope covers their fabrication and installation. Also ask about the repair of minor damage and the removal of swarf. Final cleaning should not be an unclear extra determined only at handover.

In the price schedule, keep to one method of stating tax. Compare net amounts with net amounts, and determine the final cost for the actual settlement conditions.

Prepare the supports and openings before the team arrives. Confirm that the delivery is complete and that the flashings are available. A single missing element may necessitate another visit, even though most of the panels will already be on site. Also establish how the site will be secured overnight and in the event of work being interrupted.

1. Close the measurements before ordering the cut.
2. Agree the sequence of deliveries and the storage location.
3. Confirm the date for the lifting equipment.
4. Set the acceptance of concealed works.
5. Record the rules for settling additional works.

A good quote lets you see what you are paying for and what triggers a surcharge. It does not have to be the shortest. It should be clear enough for both parties to understand the completion of a given stage in the same way.