Bill Of Quantity (BOQ) For Construction: How To Build One

Written by Bridget Cooper

DateJan 25, 2024
Reading time9 min read

In the construction industry, the execution of a successful construction project is based on the accurate cost estimations used and project management. This is the actual purpose of a bill of quantities (BOQ) for construction.

Before you build any structure, many things are involved, but only a few are crucial, like labor and materials. Without these elements, what is the use of the plan and schedule you have for the project?

Some say the bill of quantities should be used in all construction projects. Well, there is a reason for this. We'll explain all you need to know about BOQ and how to build one for your next construction project.

What is a BOQ Document in Estimating?

A BOQ document in estimating contains a list of all the materials, associated costs, labor, and quantities needed for a construction project. BOQ forms the basis of accurate cost estimation and opens doors for transparency in the bidding process.

Who prepares the BOQ? Generally, the quantity surveyor or cost consultant draws up the bill of quantities with the information provided by the design team. Ideally, it's an essential contract document between the owners and contractors.

Content and Format for BOQ

The BOQ in construction has the following components:

Item Descriptions

BOQ includes various items related to construction projects, such as labor, materials, equipment, and services. The items can include construction activities such as concrete works, electrical installation, painting, plumbing, etc. It can even cover specialized components such as fire protection, HVAC, etc.

Total Item Cost

The total item cost results from the assigned unit cost of each item obtained from market prices, supplier quotations, or historical data. The unit cost, which is the bill of materials (BOM), is multiplied by the quantity to find the cost of each item. The total item cost in a BOQ includes material costs, labor costs, contingency allowances, and subcontractor costs.

Cost Per Unit

The cost per unit is the price of each item listed in the BOQ to facilitate the estimation of the total costs required for that element.

Measurement Unit

All items listed in a BOQ have specific units of measurement, such as linear meters, cubic meters, square meters, and more. These quantities are estimated based on the drawings and specifications provided by the project team.

Importance of Accurate BOQ

The success of construction projects will depend on how prepared and accurate your bill of quantities BOQ is. Generally, BOQ assists in;

  • Precise cost estimation, therefore minimizing underestimation and overestimation
  • Effective construction project management because of a clear understanding between the project stakeholders and contractors concerning quantities and costs.
  • Smooth project execution as the materials needed and resources are readily available
  • Manage change orders if any change on the same scope is made and assess its impact on the project costs and time delivery.

Significance and Benefits

Apart from providing a detailed list of material quantities and the associated costs needed to complete the construction projects, there are benefits of BOQ. These are;

1. Effective Project Planning

With BOQ, project managers can efficiently manage resources to keep the projects on track. They have all the materials and labor available based on the project schedule and provided specifications.

2. Make an Initial Cost Estimate

Another interesting benefit of BOQ is you can make an initial cost estimate of the project. This is not just an estimation but an accurate cost estimation because it provides a detailed breakdown of the project components required and their quantities. Additionally, this is helpful to contractors and subcontractors as they can prepare competitive bids using this data.

3. Cost Control and Tracking

The BOQ for construction acts as a reference for cost control during project execution. This means project managers can keep track of all construction expenses. They will know what quantity of material was used in each phase and that it goes in line with the budget.

4. Keep Teams Productive With Resource Management Features

Since BOQ serves as an effective project planning method, it has promoted transparency in the procurement process. The project teams adhere to the resources and quantities listed in the document. This minimizes resource overuse or underuse, which affects project outcomes.

How to Prepare a Bill of Quantities

Before a project progresses after approval, the project owner needs to have a bill of quantities. This will assist in precise cost estimation and effective project planning on various construction project phases. In addition to tracking project execution, the BOQ documents serve as a critical communication tool between project stakeholders. So, project owners need to have this comprehensive document.

How do you prepare a bill of quantities?

There are six basic steps that you can use to prepare a BOQ.

Step 1: Prepare Your Spreadsheet

To create a bill of quantities, you will need to collect the project data. A spreadsheet works fine in collecting data. Create some categories in columns on your spreadsheet, such as item numbers or descriptions, total cost, labor, unit price and measurement, and description. Ensure you number all items consecutively.

In BOQ, there is something called contingency sum. These are unforeseen costs that may be incurred during the project. A contingency sum can be for a specific item or money set aside for items within the BOQ. A good example of this sum is when making additional alterations to services or any additional work to be done by the contractor on a request made by the project manager consecutively.

Step 2: Material Breakdown

After going through the detailed description of the project drawings, list the building materials needed and the quantities of each. After that, identify the unit of measurement of each material.

For example, if it's lighting fixtures, the unit of measurement you will use in Lux. This is the unit of illumination per square meter.

Then, fill in these details in your spreadsheet. Now, you can include some percentage of materials to your list to cater for any waste.

You may wonder why the bill of quantities is divided into different categories. Well, it's because there is a higher chance of your construction project being completed by different people. It usually goes in phases, with architects, contractors, and subcontractors handling different phases. Each phase has different needs, which is why it has to be itemized in a list.

Step 3: Estimation of Labor

Labor is estimated based on the number of hours the construction workers will take to finish each project phase. And since people work at different paces, a quantity surveyor can help estimate labor costs from their experience with similar projects. Still, contractors can provide these conservative estimates because they understand the scope of work and components required.

Step 4: Make an Initial Cost Estimate

After you complete labor estimates, you can now make an initial cost estimate of the construction project. Conduct market research on the material prices in the local stores. Or, better still, you can consult with contractors who have worked on similar projects in the same area.

If you're new, consider using bidding software to find such information. With an initial cost estimate, you can compare bids from other general contractors.

Step 5: Approximate Time Delivery

This is an approximation of how long the construction project will take. A labor cost estimation can assist in this case. But don't forget that things like weather also affect the project completion period, so you should also bear this in mind.

Step 6: Make Good Use of BOQ in Your Project

Now that you have everything listed maximize the use of BOQ for successful execution. It can help you create payment applications and track the quantities of materials used. This way, making an invoice amount becomes simple.

How Do You Calculate BOQ in Construction?

BOQ in construction is typically prepared by having a well-established bill of quantities like the one described above. Or you can use a bill of quantities software to calculate the project's total materials costs.

Mathematically, this formula works just fine;

Bill of Material (BOM) X No of Quantities Needed= BOQ

Every material listed in the BOQ has a unit of measurement, such as cubic meters, square meters, numbers, etc. The quantities needed for each item are based on the drawings' specifications and industry standards. So, units of measurement and quantities are essential in price cost estimation in a BOQ.

Here is an example of BOQ in construction

Let's say you want to construct a dog house. The BOQ of this project will include everything you will use to make this house. It will include nails, paint, wood, and roofing. You have to define the bill for each material and the quantities you will need for each.

Also, the labor costs should be included and this will include everything from cutting the wood, assembling the frame, nailing, adding siding, and painting. The labor cost can be avoided if you do the work yourself. Still, you can employ a contractor to assist you, considering their price offer.

What is the difference between BOQ and BOM in construction?

The main difference between a bill of quantities BOQ and a bill of materials BOM is its scope and application. Ideally, BOQ is commonly used in project management in the construction industry, whereas BOM is used in the product manufacturing industry.

BOQs are commonly used in large construction projects such as infrastructure development, building construction, and renovation projects. In most cases, it's used where projects are put out through a tendering process.

With BOQs, there is transparency in evaluating bids because everyone can access the same information and prepare accurate bids for the project. The materials are even sourced based on the quantities and the specifications needed.

Conversely, BOMs are extensively applied in the production and manufacturing industries such as electronics, automotive, pharmaceuticals, and consumer goods. It includes all parts, components, and materials needed to produce a finished product, no matter how complex or simple it is.

BOMs enable accurate cost estimation by determining the material and quantity needed for each product. This way, managing inventory and avoiding shortage or excess stock of each component becomes easy.

Written by Bridget CooperUpdated on Feb 23, 2024

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