Construction specifications, also known as specs, detail the work and workmanship needed to complete a construction project. They are part of the project’s construction documents and are provided alongside the drawing set to give a contractor detailed information regarding the materials, products, installation, and quality aspects of the project. Specs are prepared by the architect or designer prior to the beginning of construction. Sometimes, on large-scale projects, companies will even call for specialized and professional specification writers to ensure all details are covered. Each project is unique and will need a different set of specifications and most likely corresponding packages. However, there are three main types of construction specifications commonly used on projects: performance, prescriptive, and proprietary.
A performance specification describes the way that the final installed component or system must perform. The contractor is not instructed to use specific components or methods but is instructed to meet a particular function after the installation is complete. For example, a performance specification may be used for describing window systems in a building. The specification would provide required thermal resistance and infiltration values for the frame and glass along with other necessary values to define the performance of the window unit. It is up to the contractor to provide windows that meet or exceed the requirements stated in the specification. This approach can provide incentives for innovation and flexibility in the construction approach, but also reduces the amount of control that the architect or engineer has over the project.
Prescriptive specifications provide detailed information about the materials and the means of installation. This allows the architect or engineer greater control over the design selections and the final installation. Prescriptive specifications are generally formatted in three parts.
General: This section contains references to standards, design requirements, submittal requirements, and quality control.
Products: This includes detailed descriptions of products required and their performance.
Execution: This section describes how to prepare and install materials, including testing requirements.
Proprietary specifications are written to require the use of a particular product. These are often used to match a building’s existing products to allow for more consistent building maintenance. This is often the type of specification that is least used as not allowing for substitutions can potentially increase project costs during the bidding phase of a project.
If you’re in the construction industry, you know that details are extremely important – the clearer the description, the better chance it will get executed correctly. Most importantly, if specifications are done correctly, they reduce risk, and controlling risk is essential to managing the end-to-end project lifecycle. Specifications are especially important during the pricing process. With solid, detailed specs, the contractor should have no doubt about pricing.
In choosing a specification format it is important that you know what you expect. For example, in order to prepare a performance specification, you’ll need to know exactly what you want in the end. How much latitude are you prepared to give the contractor? If you want more input in the process, then perhaps a prescriptive specification is the better choice. In addition, consultation with your architect will help you with making these types of decisions.