It's a process, not just technical requirements. During design-assist, the architect of record, asks the contractor (usually a specialty subcontractor) to help develop system details and confirm system performance to meet project requirements. Typically design-assist is used for curtain wall assemblies because every installation is custom and because building envelopes are expected to be high-performing to meet energy codes and sustainable design requirements.
It's as simple as 1, 2, 3 … 4, 5, 6 …
- The architect develops a concept design.
- The owner selects a general contractor or construction manager.
- Jointly, the architect, owner, and contractor identify subcontractors capable of engineering and constructing the design.
- The subcontractor may be selected through negotiation or by bidding on the concept design.
- The contractor engages the subcontractor to provide design-assist services and to construct the design.
- The team is formed, ready to begin.
Of course their may be variations. Not all design-assist subcontractor are engaged before they help the architect. Some design-assist is performed at-risk, in hope of winning the contract as a result.
When the subcontractor is selected through a bidding process, the design-assist work package must identify the services the subcontractor is required to provide.
- Meetings - How many and how often?
- Decisions - What type and when made?
- Documentation - By whom and what purpose?
These and more must be documented in the work package specifications so the subcontractor can properly price the design-assist effort and the resulting construction.
Design, review, refine, develop, repeat, until "complete." The architect will create the design, showing the intent of the completed construction. The team will meet to review the design, discuss conditions affecting the ability to construct the design, refine the approach, and develop the next level of detail. As the process proceeds, the design matures to construction documents. The design-assist process finishes when subcontractor's documentation is a completed set of shop drawings.
Unlike delegated design and design-build, the architect retains responsibility for the design, even though assisted by the subcontractor.
Design-assist occurs early in the design process, usually at the beginning of Design Development. Not all design decisions are complete when the process begins. So the detailed project requirements may not be defined. Construction specifications are written to define the design-assist system as though the design is complete. The detail in the architect's drawings and the detail in the specifications is completely mismatched. The drawings are sketchy, lacking detail, waiting for the subcontractors assistance. The specifications are essentially complete, ready for construction.
When selecting a subcontractor through a bidding process, sufficient detail is required to ensure the bid price reflects what the project requires. Architects and envelope consultants have actually requested specifications state TBD - "to be determined" because a decision has not been made. Personally, I wince every time that phrase is inserted. It creates an ambiguity and allows each subcontractor an opportunity to make its own assumption to complete its bid.
How can bids be properly compared when based on unknown assumptions? Will the owner be faced with a change order every time a decision is finalized? Will the subcontractor be singing the refrain, "I didn't price that!"?
Consider an Alternative
Traditional construction specifications may not be the best way to approach a design-assist work package because the design is not fully developed when the package is written. Yet, construction specifications rely on material and product selections for a specific designed solution.
UniFormat based system descriptions provide a distinct advantage over traditional MasterFormat based construction specifications. UniFormat is flexible allowing performance requirements, design constraints, and system components to be specified to the degree the information is known, irrespective of the designed solution. (See Evolving Specifications for additional discussion.)
When construction specifications are written before Design Development begins to solicit bids for design-assist, the specs will contain TBDs, whether implicit or explicit, leaving the owner open for future claims for additional compensation from the subcontractor. UniFormat based descriptions removes the compulsion to identify individual materials and products while describing the design intent.