Types of Construction Specifications: Understanding the Difference

On a construction project, the specification book, often referred to as the "spec book," typically contains detailed descriptions of the materials, products, systems and workmanship required. 

The design team — architects and engineers — creates the spec book to ensure the project meets the owner’s expectation for quality and to comply with local building codes and engineering requirements. The GC and specialty contractors rely on the spec book as the project progresses to make sure their work conforms to contractual requirements. 

There are three types of specifications: prescriptive, proprietary and performance. It’s important for contractors to understand the type of specification they are reviewing in order to plan effectively, meet cost estimations and manage risk and quality. It also supports better decision-making and creates successful project outcomes.

Prescriptive Specs

Prescriptive specifications identify the specific materials and installation methods required. They may provide step-by-step details or diagrams for installation. They will include detailed descriptions, specific brand names, dimensions and methods, leaving little room for deviation.

• How to identify: Look for phrases like "must use," "shall be," or detailed lists of materials and methods.

Performance Specs

Performance specifications outline the desired performance outcomes or criteria that must be met, without prescribing the exact means to achieve them. Instead, performance specs focus on the results, such as durability, energy efficiency or load-bearing capacity.

• Why it matters: Because performance specs focus on the outcomes rather than the methods, contractors have more flexibility in choosing materials and methods to achieve specified performance criteria. They may be able to employ new technologies or methods that can offer better efficiency or cost-effectiveness. Contractors need to make sure their chosen solutions meet the desired performance standards.
• How to identify: Look for phrases like "must achieve," "performance criteria" or "meets the following requirements."

Proprietary Specs

Proprietary specs are similar to prescriptive specs in that they deal with materials used in a project. What separates them is that proprietary specs refer to specific products that must be used, like light fixtures, paint colors and countertop materials. They can also refer to existing materials — like pipes or siding — that must remain consistent. This type of spec might be used when a certain product has unique qualities that are integral to the project.

• Why it matters: Proprietary specifications call for particular products or systems, often from specific manufacturers. Contractors need to understand these specs to manage risks in the procurement process related to availability, lead times and supply chain issues. They also need to be aware of any potential liabilities associated with using specified products.
• How to identify: Look for specific brand names or product numbers mentioned directly within the specification.

The Preconstruction Playbook

Learn to navigate challenges, understand root causes, and harness technology for smoother project execution. Revolutionize your approach and unlock your team's potential.

Get the Guide

Reducing Risk & Rework

Regardless of the specification type, materials or methods will often need to be verified and approved through a submittals process before or during the project. This additional level of oversight ensures that the materials match the specs and perform as expected. 

However, contractors still need to review their contract documents to understand how different specification types may affect their legal liability. For example, depending on the way the contract is written, the contractor might bear more responsibility for deficiencies resulting from material used to meet a performance spec, while the architect might be liable for failure due to prescriptive specs. Understanding these nuances is helpful in navigating potential legal implications.

A clear understanding of the type of specification can encourage better communication with architects, engineers and clients. It help make sure all parties are on the same page regarding expectations and deliverables, reducing the likelihood of misunderstandings and disputes.

Written by