# Mechanical Estimating Methods For Construction Projects

Maintaining transparency throughout the construction process is crucial for contractors and clients. This includes open communication and putting forth accurate estimates.

Mechanical estimating involves taking measurements from technical documents and determining the quantity of materials needed for each project. It also involves analysing historical data and considering risk factors like changes in material prices or labour availability.

## Lang Method

One of the most popular methods for estimating mechanical quantities is the Lang method. This is a relatively easy method to use and can be useful for a variety of purposes, including project planning and tracking costs. However, it is important to note that generating quality estimates requires more than just experience. It also requires a thorough understanding of the project’s scope and the ability to assess the cost-to-complete each activity.

Another useful method for estimating mechanical quantities is the equipment factor estimate. This is a simple method that can be used in the early stages of the design process, when the preliminary flow-sheets have been drawn up and the main items of equipment are roughly sized. This method is based on equipment prices free at site and can be easily calculated using the formula fL = (purchase price of equipment) + (“installation factor”). The installation factor must be derived from the company’s own cost files, and it may vary between different processes.

This method is a more detailed version of the Lang Method, and it uses different factors based on the equipment type. This method is recommended by the American Association of Cost Engineers (AACE International) for Class 4 Estimates, but it is not without its challenges. For example, it is important to understand that the factors do not include indirect field costs or costs for Outside Battery Limit Facilities (OSBL). Updating & Testing the Lang Factor and its Accuracy, Precision & Reliability as a Stochastic Estimating Method – Featured Papers – Wain – October 2014

## Activity-Based Estimating (ABE)

Mechanical estimating involves the evaluation and pricing of heating, ventilation and air conditioning (HVAC), plumbing, fire strategy, and other building services for construction projects. It requires analyzing project plans and specifications, determining the quantity and type of materials needed, and calculating the labor and equipment costs. In addition, mechanical estimators must take into account the price increases that may occur during the project’s duration.

Traditional costing often allocates overhead by using predetermined rates, such as labor hours or machine hours. For example, Product 124 might demand many machine hours but little engineering or testing time. Meanwhile, Product 366 might use few machine hours but require much more engineering and testing time. In this scenario, the company might allocate much more overhead to Product 366 than to Product 124.

In contrast, activity based costing uses a more precise method of allocating overhead. It identifies all the activities that contribute to manufacturing a product, including non-production-related activities, and allocates them accordingly. For example, a company might determine that the assembly and testing of a single product demands a lot of engineering and specialized machinery. The company can then design a unit cost card for that product that reflects those specific expenses.

To accurately estimate mechanical quantities, a mechanical estimator must take a close look at the project drawings and make sure they include all required services. It is also essential to note any excluded services, assumptions and errors in the drawing. This practice will help both the mechanical estimator and the reviewers understand why a particular calculation was changed.

## Relative Value Analysis (RVA)

Mechanical estimating is a critical part of construction projects. It allows contractors to accurately forecast timelines and materials, preventing delays and remedial work. It also helps them to plan for risk factors that can affect project costs and scope. Mechanical estimating is a highly sought-after profession that requires specialized knowledge and adherence to industry standards.

To estimate mechanical quantities, the estimator must first review the project plans and specifications. This includes reviewing the drawings, analyzing the project’s scope and requirements, and assessing labour and material needs. The estimator must also be familiar with local labour rates and the availability of particular materials.

Once the estimator has a clear understanding of the project scope and requirements, they can begin the unit price estimating process. The entire project is divided into small units, and each one is assigned a cost based on its material and labor content. These costs are then summed to obtain the total Estimated Construction Cost. For example, a brick wall can be estimated by finding the number of bricks required and determining the costs of delivering, storing, staging, cutting, installing, and cleaning them.

Mechanical estimating requires a high level of accuracy and knowledge of the latest software tools and technology. The right tool can help save time and money by calculating labour and material discounts, prime costs, and other variables. It can also produce bills for clients and export reports in various formats. It is important to use a mechanical estimating program that is optimized for mechanical specialists and has a regularly updated database of materials.

## Equipment Installation Factor (EIF)

Mechanical estimating is the process of calculating the cost of mechanical systems such as heating, ventilation and air conditioning (HVAC), plumbing, fire protection, etc. for construction projects. This requires careful analysis of project plans and specifications, accurate determination of materials requirements, and thorough consideration of various factors that impact project costs.

The equipment factor method is one of the most commonly used methods for estimating mechanical quantities. It is based on the assumption that a substantial part of the total project costs are related to the installation of process equipment. The method starts with the standard costs of major types of equipment, and then multiplies them by an installation factor to obtain an estimate of the total project cost.

This method is typically performed during the preconstruction phase and may include a preliminary project description, a work breakdown structure, and quantity takeoffs. It is also known as a rough estimate, a guesstimate, or concession license estimate.

To ensure accuracy, it is essential that mechanical estimators have access to the latest software and technology. Mechanical takeoff software is a crucial tool for this purpose, enabling them to measure distances and lengths from drawings and schematics and create accurate takeoff estimates. In addition, they should stay up-to-date on the latest price changes for materials and labour. This will help them provide reliable estimates that are consistent with the industry’s best practices.