What is preliminary costing in construction?

Preliminary costing determines the estimated costs of a service before work begins. Factors taken into account include personnel, materials, vehicles, machinery, external services, overheads, and risks. This forms the basis for unit prices, the total quote, and the expected margin.

Why is preliminary costing crucial?

A quote may look attractive in terms of price but still result in a loss. Preliminary costing therefore checks the expected effort and the resulting sales price before a bid is submitted. It makes assumptions transparent and creates a foundation for later comparisons.

In construction, costing often begins with a bill of quantities, an inquiry, or custom line items. Each service is broken down into the required resources and cost components.

Typical cost components

Labor costs based on role and estimated time required
Material quantities, purchase prices, waste, and transport
Vehicles, machinery, equipment, and rentals
Services provided by subcontractors
Site and company overheads
Risks, price uncertainties, and necessary reserves
Surcharges, discounts, deductions, and target contribution margin

A logical calculation process

Review services, quantities, and execution conditions.
Determine work steps and required resources.
Estimate quantities and time requirements realistically.
Apply current cost prices and external costs.
Add overheads, risks, and surcharges in a transparent manner.
Review unit prices, total price, and expected outcome.
Clearly state assumptions and exclusions in the proposal.

Simplified example

A line item requires 40 labor hours, materials costing CHF 3,600, a machine for two days, and transport. These direct costs are supplemented by company-defined overheads, project-specific risks, and the desired profit margin. The key is not any single surcharge, but ensuring the values used align with the business and the service provided.

NPK and preliminary costing

The Standardized Item Catalog (NPK) structures the scope of services. The calculation complements this with quantity, effort, and price. Standardized items do not replace professional assessment: variables, preliminary remarks, execution conditions, and quantities must still be understood.

Pre-calculation does not end with the contract award

After the order is placed, the calculated values become target values for purchasing, work preparation, and project management. During execution, hours, material, and measurementshow whether the assumptions still hold true. After project completion, the post-calculation provides the decisive feedback.

Digital estimating

When the bill of quantities, items, prices, and project are digitally linked, data does not need to be transferred multiple times. With Caturix Offerten , you can build and calculate both custom and NPK-based quotes and assign them to the subsequent project.

Frequently asked questions about pre-calculation

Can you calculate without a bill of quantities?

Yes. For smaller or self-defined services, the company can create its own items. The scope of services, quantities, and assumptions must still be clearly described.

How up-to-date must the baseline data be?

Price lists, wage rates, and empirical values should be maintained regularly. Outdated master data will produce unreliable results, even with sound calculation logic.

Is the calculated margin already the project profit?

No. It is an expectation based on the costs and assumptions used. Only the actual quantities, costs, and revenues reveal the real result in a target-vs-actual comparison.

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Quellen und fachliche Prüfung

Die Inhalte werden redaktionell geprüft. Bei Normen und Standards nennen wir die verwendeten Primärquellen; allgemeine Begriffe basieren auf erprobter Schweizer Baupraxis.