What Is Assemblies Estimating?
The grouping of multiple line item costs into building components or broad building elements is called the "Assemblies" method of estimating. This method allows the designer to make quick comparisons of assemblies and systems in various combinations. The assemblies that are best suited to accommodate budget, code, load, insulation, fireproofing, acoustics, energy considerations, and the owner's special requirements can quickly be determined.

Assemblies Estimates vs. Unit Price Estimates
In order to understand how an Assemblies estimate is developed, it helps to compare a Unit Price estimate with an Assemblies estimate. In a Unit Price estimate, each line item cost is normally grouped with other line items dealing with similar materials or equipment — a Unit Price esimate is usually organized using CSI's MasterFormat^™ (the traditional 16 Divisions, now 50 Divisions). In an Assemblies estimate, the cost items are organized by the building element or component they are a part of, rather than by the materials they are built out of, using UNIFORMAT as the organizational scheme. For this reason, some identical line items may appear in two or more systems.

A good example is concrete. In a Unit Price estimate, all the concrete items on a job would be grouped together in the Concrete section of the estimate, MasterFormat Division 3. In an Assemblies estimate, concrete is usually found in many locations, such as Foundations, Basement Construction, Superstructure (columns, beams, and floors), and Exterior Closure (load-bearing walls and shear walls).

Conversely, assemblies might combine items that are listed in separate Divisions in a Unit Price estimate. For example, interior partitions might include line items from two MasterFormat divisions: Division 6, for wood studs, and Division 9, for lath, plaster and paint. In an Assemblies estimate, these items are all combined in UNIFORMAT, Division C, Interior Construction.

This switch from using the CSI MasterFormat organization to using the UNIFORMAT organization may at first seem confusing, but once the concept is understood, the resultant increase in estimating speed is well worth the initial familiarization required.

When Assemblies Estimating Is Appropriate
Assemblies estimating is normally done during early conceptual stages, often before any drawings have been prepared, to aid in preparing a budget or to enable the designer to bring the project in within the owner's budget.

During the subsequent design process, the designer will be making important decisions, often involving "trade-offs" for some systems. Based on these decisions, the designer will substitute different assembles for those included inm thee initial estimate. Common trade-offs involve:

• Price of each system.
• Appearance, quality and compatibility.
• Story height.
• Clear span.
• Complications and restrictions.
• Thermal characteristics.
• Life cycle costs.
• Acoustical characteristics.
• Fireproofing characteristics.
• Special owner’s requirements in excess of code requirements.
• Code restrictions.
• Loading limitations.

Preparing an Assemblies Estimate Using CostLink/AE
Although CostLink/AE can be used to prepare an Assemblies type estimate manually, its real power is in its automation of the R.S. Means Square Foot Cost Models. Read about that here. Before starting your estimate, you will need the following information, which the software will prompt you for:

• Identify the most similar Means Building Model.
• Preferred structural frame and enclosure systems.
• Gross square footage.
• Length of perimeter.
• Number of stories.
• Project location (state and city for local cost adjustment).
• Applicable sales tax.
• General contractor overhead and profit percentages.
• Architect's fees, if any, as a percentage.
• Any budget contingency, as a percentage.

In addition, each building model offers a different set of "additives" appropriate to that building type. These are items that may or may not apply to your project. You'll need to review these at the time you begin your estimate.