1.1 Purpose

Please note: If some of the terms used in this manual are unfamiliar, refer to section 1.3, Definitions for a detailed explanation.

Building cost is usually established by breaking a building design into discrete items of a known cost. That list of items is usually referred to as a Bill of Quantity. In the past, drawings have been physically measured to calculate quantities against bill items. Even now, ARCHICAD models are often exported in 2D formats or printed for this measurement process, losing valuable data and opportunities for BIM quality checks.

Quantities is designed to facilitate a standard measurement process directly on an ARCHICAD model to populate a Bill of Quantities with quantities and cost, resulting in a total cost estimate for project delivery.

An overview of the process and tools is illustrated below.

The upper row – what we want – shows the costing process from producing a model through to calculation of quantity:

A. Modelling the building;

BIM projects are far more than geometry – attributes such as materials and other metadata including properties and classifications are a rich source of costing data. These resources are becoming more valuable as the industry moves further to BIM, increasing the need for effective management and auditing.

B. Establishing a bill structure and suitable measurement processes;

The bill is a formal list of building cost items including a rate and unit. The source of the bill may be a database, online resource or internal expertise. The measurement processes must allow for a single element to contribute quantities (and cost) to many different bill items.

C. Calculating, presenting and checking calculated quantities and cost.

Quantity take-offs can involve a lot of manual intervention or measurement, to the point where cost checks are only carried out very late in the documentation process.

The lower row – how it’s achieved – summarises three tools added by Quantities:

A. Quantities Info palette

For entering, managing and auditing attributes, properties and classifications that contribute to quantity measurement (see section 2, Project Data Management). This helps to ensure the properties impacting on cost are managed from the start and can be effectively audited as the project develops.

B. Quantity Take-off Manager dialog

Manages the bill structure  (see sections 3, Bill of Quantities) and recipes/rules that define the measurement process (see 4, Defining Measurements). This provides the management tools required for effective cost measurement.

C. Bill of Quantities palette

Displays the calculated bill with a range of cost auditing tools (see section 5, Generating Quantities). Carrying out the measurement process in ARCHICAD ensures the source of the data can be checked in conjunction with the calculated item quantities and corrected in situ.