Have you ever seen supplemental and additional services listed on a contract and wondered what the difference is between the two? This is a common question in our PjM virtual workshops and although they sound similar, they have distinct meanings. Understanding the difference between these two types of services is very important for managing the scope of the project, your fees, and the client’s expectations. Let’s take a look at each of these terms and how they relate to AIA contracts.
Before getting into supplemental and additional services, let’s briefly review the architect’s basic services according to AIA B101 Article 3. The architect’s basic services include architectural design services for the schematic design, design development, construction documents, bidding & negotiation, and construction administration phases as well as usual and customary structural, mechanical, and electrical engineering services. Any services not listed in Article 3, are considered supplemental services.
Supplemental services are services that the architect and the owner agree upon at the time of contract execution to be part of the project’s scope, but that are not part of the architect’s basic services. Examples of supplemental services include:
- Measuring and documenting existing conditions
- Civil engineering and landscape design services
- Designing to and applying for LEED certification
- Record drawings
- Post-occupancy evaluations
The key feature of supplemental services is that they are pre-identified before the contract is signed. Article 4.1 of AIA B101 lists many common supplemental services in a table with space to identify who is responsible for the service - the architect or the owner. For example, the owner may choose to hire their own civil engineer. In this case, “Civil Engineering" is assigned as the owner’s responsibility in Article 4.1 of AIA B101. Even though the architect isn’t providing this service, it’s still important to include it in the contract between the owner and the architect because the architect will be coordinating their work with the owner hired civil engineer.
Additional services are services that arise after the contract has been signed and were not anticipated at the time of contract execution. They are typically triggered by events or changes during the project. Examples of additional services include:
- Revisions to previously approved documents
- Redesign due to changes to the project scope or budget
- Requests for a service not initially anticipated
- Extensive rebidding due to market changes
- Additional construction phase services than initially anticipated
The key feature of additional services is that they are un-identified at the time the contract is signed. Since additional services are not included in the initial contract, they are executed via contract amendments and must be signed by both the owner and the architect before work commences on the additional service. If needed, a supplemental service listed under Article 4.1 of AIA B101 may be added as an additional service if it wasn’t initially included as a supplemental service when the contract was signed.
To recap, the main difference between supplemental and additional services is that supplemental services are identified before the contract is signed and included in the initial contract between the owner and the architect. Additional services are un-anticipated before and added after the contract is signed.
Here are two posts with more discussions on supplemental vs. additional services:
Happy studying!
Emely Taveras Robbs, AIA, NCARB
Architecture Learning Manager
Black Spectacles