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Author(s): Matt Klaus. Published on May 2, 2016.

Best-Laid Plans

The difference between working and preliminary plans


WHEN WORKING ON A SPRINKLER DESIGN and installation project, you hear a lot of people refer to certain project documents generically as “the plans.” When dealing with design concerns, compliance questions, coordination issues in the field, or disagreements between the design and installation teams, however, it’s important to go deeper than simply referring to “the plans.”

NFPA 13, Installation of Sprinkler Systems, distinguishes between two types of plans that are often created during the design process. This concept, which is used throughout the industry, focuses on both preliminary plans and working plans. Preliminary plans provide a high-level account of how the system was designed. This may include conceptual sprinkler layouts, but focuses on the decisions made during the design process that will lead to the system that is eventually installed. Specific items included in the preliminary plans include the hazard classifications for various portions of the building or the commodities that are being stored for warehouses or distribution centers. Information on the system type (wet, dry, preaction, etc.), the required density, and water supply are fundamental to the system and are included on preliminary plans. In many cases, preliminary plans are prepared by a licensed fire protection engineer or other design professional approved by the authority having jurisdiction (AHJ) as part of a permitted set of drawings. These plans may not be used for the final system installation, but they provide all of the critical information for the plan reviewer or AHJ to allow the project to move to the next stage.

In preparing the preliminary plans, the engineer or other qualified designer should take the concerns of the owner into account so that the sprinkler system meets the current and future needs of the owner’s intended use of the space. To facilitate this objective, the owners information certificate, which is shown in NFPA 13 Figure A.23.1(b), is included in the standard. The use of this certificate helps ensure that both the preliminary and working plans address the owner’s project requirements.

Working plans provide a much more detailed look at the system and include critical information for the installing contractor. Working plans are typically prepared using the preliminary plans as a starting point, and layers of detail are added as the building geometry and the locations of other building systems are finalized. Items that may not appear on the preliminary plans, including the location and type of sprinklers, valves, pipes, hangers, and other system components, are integral to a working plan set. These plans, also commonly referred to as “shop drawings” or “construction documents,” include the layout of the entire system along with its hydraulic calculations.

Since these are the plans that will be used to drive the system installation, the AHJ or plans reviewer must approve these documents before installation can begin. NFPA 25, Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, requires the owner to retain the initial working plans and specifications to facilitate the necessary inspection, testing, and maintenance activities. Having these plans handy will also help facilitate future modifications or additions to the sprinkler system.

These two types of plans serve different, and critical, functions in a sprinkler design and installation project. The decisions outlined on the preliminary plans will carry over into the more detailed working plans; the preliminary plans should not be dismissed as a mere formality to obtain a permit. It is important for all stakeholders to understand the different objectives of these plans so they can be more effectively utilized during a project’s lifecycle.

MATT KLAUS is principal fire protection engineer at NFPA and staff liaison for NFPA 13, 13R, and 13D. Top Photograph: Courtesy of Stephan LaForest