Top 10 “Must-haves” in Plumbing and Fire Protection Design
Plumbing and fire protection systems are often the most overlooked portions of MEP design, and therefore are often not given the same level attention as the other systems. However, improper design choices and lack of coordination for plumbing and fire protection are extremely detrimental to a building and its occupants. These mistakes can lead to increased cost and schedule delays if caught during construction. However, many of these issues are not identified until the building is complete, resulting in major repair costs, critical life safety concerns, shutdown of the building, and even irreversible damage to building structure. This is why it is paramount to have a design team who understands the significance of these systems and all the different design components that must be incorporated to achieve a successful project. Here are our top ten “must-have” plumbing and fire protection design considerations:
Geotechnical Report
Although many view the geotechnical report as a document only relevant to structural and civil engineers, the contents of it can change the plumbing design entirely. Soil movement is arguably the single most damaging force on a plumbing system, and the geotechnical engineer has the expertise to know how these risks should be addressed on a particular site. When a slab-on-grade foundation is recommended, direct burial of the below slab piping is typically sufficient (assuming the soil has been treated to an acceptable potential vertical rise) as both the building and the soil will move together. However, when a structural slab system is used, any buried piping will want to move with soil while the piping and fixtures in/above slab will want to remain stagnant with the building. This can result in broken pipes, structural damage, floor drains protruding up from the slab, and more. The latest edition of the International Plumbing Code (2024 IPC Section 305.8.2) even goes as far as to require both the piping and piping supports under a structural slab be completely isolated from the expansive soil. If a structural slab is to be used, the plumbing designer should collaborate with the geotechnical and structural engineers to ensure the solution for mitigating these risks is included in the report by the geotechnical engineer and then incorporated clearly into the building design documents.
Poop Goes Outside
Probably the most important thing for the occupants is, once you…. “drop the kids off at the pool” you don’t want to be reminded of them again. There are a few things we consider when routing the sanitary line. First thing is the slope. If the slope is too shallow, nothing will flow, but if the slope is too steep, the water will move too fast and not carry any of the brownies out with it. We also consider the routing of the lines, reducing the amount of turns and providing gentle turns where needed will help Nemo have an easy journey to the ocean without getting stuck. Lastly, we also need to thoughtfully place cleanouts for when Taco Tuesday turns into a traffic jam in the pipe, a plumber will need a way to access it and direct traffic with an auger or drain snake.
Interceptors
There are lots of things we put down the drain that can’t go into the city wastewater, so they need a way to be treated or removed. For example, the grease in the kitchen will congeal and clog up the pipes so it needs to be contained in a trap and separated from the water, to be pumped out. Science labs will often deal with acid that needs to be neutralized in a special tank, so it doesn’t dissolve the sanitary mains. There are also special traps for solids, sand, hair, lint, plaster, and oil.
Civil and Structural Coordination
Coordination extends beyond the building’s interior once piping systems are installed. Effective communication with civil and structural engineers is critical for ensuring a well-designed structure. The dimensions and depth of sanitary and storm piping, determined by fixtures and distances within the building, must align with the civil engineer’s specifications to ensure proper drainage away from the building and site. Additionally, essential components such as Fire Department Connections (FDC), Post Indicator Valves (PIV), and backflow preventers require careful coordination with the civil engineer to ensure optimal placement for firefighting purposes. For projects involving internal roof drainage, collaboration with the structural engineer is vital for the strategic placement of roof drains and the routing of associated piping. Furthermore, special attention is needed for piping routed alongside grade beams below the slab and metal framing above the slab.
Field Inspections
Even with an excellent set of contract documents and a skilled contractor, mistakes will be made during construction. Whether it be a misinterpretation of what is shown on the drawings, miscommunications between the GC and the subcontractors, unexpected field conditions, or a multitude of other issues that may arise during construction, it is our job to make sure the owner is delivered the building they were promise. By maintaining a constant presence on the job site, the designer is able to resolve most problems before they even arrive, as well as make sure the contractor is staying in alignment with the contract documents before anything is covered up. In plumbing this is especially important as everything starts from the ground up. Once your below-slab utilities are covered there will almost certainly be added cost and schedule delays to revise them. Consistent field inspections benefit not only the owner but the contractor, architect, other consultants, and everyone else involved in the project.
Flow test
One of the first things a plumbing designer will ask for at the start of a project is a hydrant flow test. This test is performed by taking pressure and flow measurement at the two nearest fire hydrants to the new building site. The results of this test will allow the designer to determine exactly what flow and pressure can be expected coming into the building from the city main. These will then be used to a) determine if a pump will be needed for the fire protection and/or domestic water and b) calculate the pump demands. For certain buildings, such as high-rises, the design team can reasonably assume from the start that a pump system will be needed for both the domestic and fire protection systems. However, for most education projects due to their standard low-rise design, the need for a pump is dependent entirely on this flow test. Although it might seem like including a pump from the start is the most straight-forward solution, this results in significant (and possibly unnecessary) cost. Not only is the pump itself a pricy item, but the architect must carve out space for it, which adds square footage to the building. In certain jurisdictions, including Houston and the surrounding areas, a 2,500-gallon break tank is also required wherever a pump is provided to prevent damage to the city mains. This break tank alone can take up nearly 200 square feet in the building, plus more needed for maintenance clearances, and adds a great amount of cost to the project which is often unaccounted for. By receiving and analyzing the flow test early in the design process, the plumbing designer can either confidently exclude these items from the scope of the project allowing those dollars can be allocated elsewhere, or confirm they will be needed so those concessions can be made early on and are not a surprise to the owner and architect late in the design process.
System Maintainability
Building maintenance demands a significant time investment, which may not be feasible for all building owners. Designing systems without considering accessibility can result in increased downtime during repairs and higher maintenance costs. It is essential to provide adequate space for accessing and servicing equipment and to ensure that accessible cleanouts are installed with thoughtful consideration of the pipe routing they serve. When selecting plumbing equipment, prioritize durability and ease of maintenance. Evaluate whether the equipment can withstand regular use, meets the end user’s needs, and has accessible components for repairs, thereby minimizing the risk of frequent maintenance issues.
Building Design and Aesthetics
Balancing Functional and Aesthetic Design: Plumbing designs should not only reflect compliance with rules and regulations but also with the intents of the architect and owner. Constant communication with the architect and owner can help a plumbing designer align their systems with both the forms and functions of each different space. Through strategic planning, items that are typically regarded as “eye sores” (access panels, clean-outs, floor drains, etc.) can be incorporated into the architect’s vision for the space while providing the building owner and occupants with full functionality and improved maintainability of all fixtures, piping, and equipment. This in conjunction with the engineer’s discretion, which includes the selection and placement of plumbing pipes and fixtures, enables the creation of a visually pleasing design that can satisfy every party involved.
MEP Systems Coordination
MEP engineers manage a range of systems beyond just plumbing and fire protection, including electrical systems, HVAC, and sometimes technology systems. To ensure these systems function together, meticulous design coordination is essential. Without it, conflicts during construction, operational inefficiencies, safety hazards, and increased costs can arise. For example, storm and water piping should avoid crossing over electrical and IT rooms, and storm drain routing can affect HVAC duct design in cramped plenum areas. Effective plumbing design relies on early and ongoing collaboration among all MEP disciplines. To achieve the highest quality outcomes, MEP engineers must enforce a rigorous QAQC process, maintain clear and consistent communication, and address potential issues proactively. These practices are critical for delivering exceptional results for clients and building owners.
Cohesive Drawings and Specifications
Drawings are obviously important for the contractor to know what they are building but putting equal time and energy into the specifications is critical for the project to come together. Specifications are like the long book of instructions you get with your Ikea dresser that you toss and then realize halfway through that something isn’t right. Specifications will provide a more detailed explanation than the drawings can go into on how certain things should be installed, including with what materials or products to make sure everything is built to correct standards.
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