A substitution is a proposal from the Bidder/Contractor to substitute a product, material, or system for that specified in the Bid or Contract Documents complete with a statement of impact on the Contract Price and/or Contract Time.

Product substitutions are a normal part of construction; few projects get built without at least one substitution request being submitted (if not approved). But the architect must manage the process to ensure that only substitutions that truly benefit the owner or are for a legitimate cause are submitted, that the rules for requesting substitution are clearly described, and that the design team is appropriately compensated for the additional services. Properly managed, approved substitutions can, by lowerig the construction cost, shortening the construction schedule, or improving the quality, even result in a better project.

The substitution of a product for a specified one is normally considered an issue during the bidding and construction phases. However, planning for substitutions, understanding that they are sometimes unavoidable, and developing a process for evaluating them need to start at the very beginning of the project. And by “beginning,” we are talking about before the architect signs the contract with the owner.

To some extent, the likelihood of substitutions being requested during bidding and construction can be mitigated by careful material and product selections during the design phases. This can start by setting and following project team design goals. Before any design effort begins, the architect should lead a visioning and goal setting session that includes the owner’s decision-makers, consultants (architect’s and owner’s), construction manager/advisor (if any), and other major stakeholders in the project. One of the results of this goal-setting session is establishing the level of quality of materials and systems, in terms of durability and performance. All material selections made by the design team should then be consistent with those project goals.

From: American Association of Architects. "Product Substitutions" White Paper. By William Schmalz
http://network.aia.org/AIA/AIA/Resources

In evaluating schedule and cost, be sure to include the time and effort required to modify the construction documents and obtain any required approvals from authorities having jurisdiction. While one product may be $1000 less expensive to purchase than another, if it requires $2000 of consultants time to revise the drawings to accommodate the proposed product, it is not a savings to the Owner.

Our most frequent requests relate to products without the apparent ULC or other approvals. The Contract should be told to provide those requirements or covering documentation before any further examination is done. Requests for Substitution during construction may be time consuming and potentially liability inducing. How can the architect be reimbursed when the time becomes onerous. Obviously any required changes to drawings can be charged to owner as changes of scope but other costs are more difficult. They result from the contractors proposals usually.

Where the consultant has properly researched a product before specifying it, there are only two legitimate reasons for considering a substitution after award of the contract:

1) the proposed product is available sooner, thereby allowing the project to be completed earlier; or

2) the proposed product meets or exceeds the requirements of the specifications and is ultimately less expensive for the Owner.