In plumbing projects, piping is a key component of the overall project cost. However, there are many other variables to consider, including labor costs. To get the most accurate estimate, it’s important to prepare a comprehensive plan.
Creating accurate takeoffs requires extensive knowledge of materials, specifications, and labor rates. The piping estimator must also know how to use spreadsheets.
Pipe sizing
Pipe sizing is the process of selecting the proper diameter for a pipe based on its flow rate. This is an important part of the piping design process, as it ensures that the system will be able to handle the desired load without overflowing or underflowing. It also helps to reduce maintenance costs by ensuring that the system is adequately sized for the load it will carry.
A common sizing method is to use a quick sizing table, which is available in most engineering software programs. The sizing table allows you to choose the desired fluid velocity, pipe material, tank and flush valve type, and C-factor. Once you have these values, the calculator will determine the appropriate WSFUs and GPM conversions.
The sizing calculations use the Hazen-Williams equation, which considers the pressure drop and velocity of the piping system. This approach is not accurate for laminar flow or extremely turbulent flows, but it can be a good starting point for your design.
It is important to keep in mind that the sizing results are only approximate and will vary from project to project. Using the correct size for a pipe increases efficiency and reduces the cost of installation, operation, and maintenance. It is also important to understand the limitations of these sizing calculations and how they relate to specific applications.
Material requirements
In addition to labor costs, a pipe estimator must take into account the cost of materials and other supplies required for the project. This includes the piping itself, but also items such as valves, fittings, and fixtures. Using specialized software can help streamline this process and ensure accurate calculations.
The first step in determining material requirements is to review the architectural drawings and specifications for the project. This will determine the type and size of pipes needed for the job, as well as any special considerations such as plumbing code requirements or building layout. Then, the estimator must estimate the quantity of each item and determine the total amount of material required for the entire project.
Another important factor to consider is the effect of temperature on piping materials. Each material has a specific coefficient of linear expansion, which is the rate at which it expands per degree of temperature change. In some cases, the expansion of a piping system can affect its final length significantly. For this reason, it is essential to have an accurate understanding of the effects of temperature on piping systems.
Finally, the estimator must establish a pricing standard for each item of piping material. This is usually based on industry standards or the prices of competing companies in the area. It is a good idea to check competitor prices on a regular basis to make sure that you are keeping pace with the market.
Sub-contracting
Sub-contracting involves contracting out parts of a job to other workers or small companies. This can be a cost-effective way to complete a large project, but it also adds risk to the contractor. It is important to understand how the type of sub-contracting will affect your project, and it is important to negotiate a contract with the gas company that covers all potential risks. One option is to agree to a Cost Plus Percentage contract, where the contractor will bill the gas company for all costs and pay any cost overruns. This is a great option for projects with uncertain scopes of work, or for those who do not want to be responsible for the full risk of the project.
The other option is a Unit Price contract, where the contractor is paid based on actual direct job costs and the owner’s estimated quantities for each task. The contractor can reduce the risk of inaccurate estimation by raising unit prices for some tasks, but may have to pay a penalty for delays or cost overruns that increase its unit prices. Regardless of the type of contract, it is important to ensure that your pipe estimator is using an accurate digital takeoff system for material quantities and labor hours. This will allow your estimates to be more precise and will help you bid more competitively on new jobs.
Detailed estimation
In addition to raw materials and labor, a plumbing estimator needs to factor in other costs. These include overhead and profit, which should be calculated based on industry standards. These are determined by a number of factors, including the type of work being performed and local regulations. It is also important to take into account unforeseen challenges and provide contingencies in the estimate.
Piping estimators must be able to read engineering drawings and be proficient in cost estimating software. They may specialize by service, product, or project type. They must also be familiar with pipe fabrication methods and material specifications. Piping estimators must be able to make accurate estimates and be capable of processing the final cost data for use in the corporate database.
A good plumbing estimator will be able to calculate all the required parts and labor for a particular job. This will include analyzing the architectural drawings and determining the proper sizes and types of pipes required. They will also be able to determine any subcontracting requirements and make allowances for labor and other costs. This process can be time consuming and requires a lot of careful planning.
Piping estimators must also keep in mind building codes and regulations, which establish standards for piping systems. This includes sizing, venting, and clearance requirements. Additionally, they must consider the types of valves and fittings to be used. These factors can significantly affect the total cost of the piping system.