Plans and Specifications (P&S) is the traditional method for project delivery and differs in several substantial aspects from Design–Build.
In the P&S method of project delivery, the Owner of the project contracts with separate entities for design and construction.
There are three main phases: the design phase, the bidding phase, and the construction phase:
- Design Phase: An Architect or an Engineer designs and produces documents on which General Contractors will bid and ultimately be used to construct the project.
- The Architect works closely with the Owner to identify the needs of the project and to develop a written description and schematic design drawings. This is further developed into a “biddable” set of plans.
- Various professionals are used to come up with the design and specifications for the project including Structural and MEP (mechanical-electrical-plumbing) Engineers.
- Bid Phase: The bidding phase can be “open” – any qualified bidder can participate – or “select” – few pre-selected Contractors are invited to bid.
- General Contractors (GCs) receive the bid documents and contact various sub-Contractors to receive bids for sub-components of the project.
- The Architect reviews bids, seeks out any clarification needed of the bidders, makes sure documentation is in order and discusses the ranking of the bids with the Owner.
- If the bid is acceptable to the Owner, the Owner can discuss the proposals further. The Owner will not necessarily pick the lowest bid by a GC since past performance and quality of work also play a role in the selection process.
- Construction Phase: Construction documents may have to be updated to account for addenda or other changes, but approvals must be achieved through the proper authorities in order to begin construction.
- The Architect acts as an agent to the Owner to ensure that the work is progressing appropriately and also to issue site instructions. Changes may be made to the drawings to make them more or less expensive. The project is constructed. Sometimes, it is abandoned.
- Potential problems
- Failure of the design team to be updated with construction costs in excess of original design due to changes.
- Redesign expenses can be disputed
- Tendency for General Contractors to seek out sub-Contractors who offer the lowest cost to ultimately end up with a “cheaper project”
- Disputes between the design team and Owner
- Disputes between the Architect and General Contractor
- Benefits
- Design team is impartial
- Fairness to potential bidders and gives the Owner more options
- Engineers often help Owners in the transition to building operation. E.g. They remind them that they have to regularly service their brand new equipment.
- When the “right” design is selected that represents the best value and the “right” Contractor is picked, the competition for the work improves efficiency and quality for Owners. This unfortunately does not happen enough.
The main difference from Design-Build Construction is that the Owner is now “in between” the design team and the constructors. In P&S construction, it is the Owner’s “responsibility” to bring a buildable design to the construction team. In Design-Build, it is the design team’s responsibility to design the building AND build it.
From the mechanical design aspect, the P&S process works well for projects where the design team has a lot of experience and knows what they are looking for, like in the case of retail or restaurants where literally hundreds and sometimes thousands of basically the same space are built. The process also works well for specialty projects where little design knowledge exists or where there are severe architectural, structural, or other limitations to the mechanical design.
AT Mechanical works well on Plans & Specifications projects and also on Design-Build projects. Having a lot of experience with Design-Build helps us understand the design process used by the mechanical and other Engineers on each and every project. After all, we are Engineers also! This knowledge helps the General Contractor deliver the best value to the Owner as we can offer many options and different methods of construction….if we are asked to do so.
Otherwise we can build it exactly the way it is drawn. It’s your choice.
