Flood risk exists on a spectrum defined by FEMA flood zones, Base Flood Elevations, and site topography. Before design begins, every part of the site must be thoroughly mapped and evaluated within that broader context.

Key Considerations

• Obtain current FEMA Flood Insurance Rate Maps (FIRMs) for the site and identify which zones apply. VE (coastal wave action), AE (tidal/river flooding), or X (low risk).
• Determine the Base Flood Elevation (BFE) for each zone. Many localities adopt additional elevation requirements above BFE, known as freeboard, through their local floodplain management ordinances or zoning codes. Always confirm the locally adopted Design Flood Elevation (DFE) before establishing your construction target.
• Use NOAA sea level rise projections to understand where the water will be relative to the building at year 20, year 30, and year 50 of its lifespan. FEMA maps account for storm events and floodway impacts, but they are a snapshot. Sea level rise projections put the building’s long-term relationship to the water in context.
• Document any variances or special permits that may be required for structures located in the most restrictive flood zones, particularly for water-dependent uses.

Not every building requires the same level of flood protection. The decision of where to position a building on site is one of the most consequential choices a team can make. Building within a floodplain, whether elevating or flood-proofing, adds substantial cost and complexity. Strategically pairing each building’s purpose with the right location is the most effective first step to reduce risk.

Key Considerations

• Ask early whether each building is truly water-dependent. If a building’s core functions require direct, reliable access to the water, it may justify the added cost and risk of a waterfront location. If the answer is no, placing the building further upland is almost always the lower-risk, lower-cost decision over the life of the project.
• As distance from the water increases, flood risk generally decreases and the ground naturally rises, opening the door to a more simple, less costly construction approach. Use this shift in elevation intentionally when organizing a project’s program across a site.
• Locate support functions (administration, housing, storage, etc) further from the water, where flood risk is lower and construction is more straightforward.
• For buildings that must operate continuously regardless of weather conditions, evaluate where system backups and hardened construction are warranted. This is separate from water dependency. A building can be mission-critical without needing to be at the water’s edge.

There is no single flood-proof solution. The most resilient projects often employ multiple strategies simultaneously, each calibrated to the specific building, its flood zone, and its operational requirements. Understanding the full range of available approaches allows the design team to match the right strategy to each building’s location, function, and risk profile.

Key Considerations

• Permanent – Raise the finished floor elevation above the Design Flood Elevation (DFE) on piles or columns. Best for buildings that must remain fully operational during a flood event and do not require ground-level access for daily operations.
• Contingent (Wet or Dry) – Rather than elevating the finished floor above the Design Flood Elevation (DFE), contingent flood-proofing accepts that floodwater may reach the building and designs accordingly. Wet flood-proofing allows floodwater to enter the building, ensuring the structure resists hydrostatic pressure while interior materials are rated for submersion or elevated above the anticipated flood level. Dry flood-proofing keeps floodwater out entirely using waterproof membranes and deployable barriers. In both cases, the foundation must resist buoyancy and lateral water pressure.
• Portable – Design structures on trailers or skids so they can be relocated before a storm event. Best suited for temporary or auxiliary facilities.
• Emergency – Deploy temporary flood barriers in advance of a storm. Most effective as a secondary layer of protection rather than a primary strategy.
• Jack-up – Mechanically elevate a structure after installation using a hydraulic lift system. Useful where future flood risk is uncertain or conditions are expected to change over time.
• Amphibious – Design the structure to rise with floodwaters, tethered to guide posts. Best suited for areas with slow-rise, predictable flooding where traditional elevation or flood-proofing is not practical.

Flood-resistant buildings must withstand more than water depth. They need to account for the physical forces of flooding, including hydrostatic pressure from standing water, hydrodynamic forces from moving water, wave action, buoyancy uplift, and debris impact. The structural system must be engineered for these dynamic conditions from the ground up.

Key Considerations

• Foundation – Design pile foundations to resist buoyancy and lateral hydrostatic forces. The pile system, caps, and grade beams work together to anchor the building against uplift and movement during a flood event.
• Walls – In zones subject to wave action, reinforced cast-in-place concrete walls are designed to resist hydrostatic pressure from both sides. Wall thickness and reinforcement are determined by the specific forces anticipated for the flood zone.
• Slab – When a finished floor is intentionally positioned below the Design Flood Elevation (DFE), the floor slab is often structurally integrated with the surrounding walls to create a unified system capable of resisting hydrostatic uplift. In a dry flood-proof condition, designers must detail water stops at the slab-to-wall connection to prevent water intrusion. At the same time, they must resolve the interruption of code-required continuous insulation at that same joint. These competing performance demands require careful detailing early in the design process.
• Openings – Design all doors and windows with sill heights relative to the DFE. Where operational requirements demand openings below the DFE, specify a deployable flood log or flood gate system.
• Mechanical and Electrical Systems –All mechanical and electrical equipment must be elevated above the Design Flood Elevation (DFE). This has wider design implications. Electrical outlets, distribution panels, and equipment must be high enough to stay dry while remaining within code-required reach ranges for accessibility. Designers should anticipate these conflicts early and resolve them before construction documents are finalized.

Coastal environments subject every material to accelerated corrosion from salt air, direct saltwater contact, and humidity. Material selection failures in these conditions go beyond appearance. They represent structural and operational failures that compound over time. Design teams must evaluate corrosion resistance for every material and assembly from the very beginning of the project.

Key Considerations

• Fasteners and Connectors – Specify stainless steel (316 grade minimum) for all exterior fasteners, hangers, anchors, and connectors. Standard galvanized hardware fails rapidly in salt air.
• Railings and Screens – Fiberglass-reinforced polymer (FRP), stainless steel, aluminum, and wood are all viable options for exterior railings depending on the project context. Each has different maintenance requirements and lifespans in a coastal environment. Evaluate the tradeoffs for specific application.
• Piping – Specify PVC or CPVC for water piping where allowable by code. For compressed air systems, building codes typically mandate steel piping. In those cases, evaluate alternative materials and pursue a code variance where steel would be vulnerable to corrosion over time. Specify stainless steel hangers, fasteners, and supports throughout all exposed areas.
• Exterior Cladding – Specify phenolic panel, fiber cement, or other non-metallic cladding systems. Ensure that all fasteners are compatible with the cladding material. Do not use steel fasteners with cladding systems that will accelerate their corrosion.
• Insulation – Specify closed-cell spray foam or other moisture-resistant insulation systems in areas subject to humidity and occasional wetting. Avoid open-cell or fiberglass batt in exterior wall cavities in marine environments.
• Mechanical Equipment and Conduit – Specify marine-grade coatings on all exterior mechanical equipment housing. All conduit should be non-steel. PVC or aluminum conduit are appropriate alternatives that will not corrode over time.

Sea level rise, evolving operational needs, and intensifying storm cycles mean coastal buildings must be designed for change from the outset. Flexibility is a core resilience strategy. A building that can adapt to shifting environmental conditions over time is far more valuable than one optimized solely for today’s baselines.

Key Actions

• Open Floor Plans – Minimize interior structural columns in working spaces to allow future reconfiguration of equipment and workstations as operational needs change over time
• Accessible Utilities – Route all piping and conduit in overhead or accessible chases. Never buried in slabs. Future changes to building systems should not require concrete demolition.
• Floor Drains – Floor drains in a floodplain require careful detailing. Every penetration in the slab is a potential path for water infiltration under hydrostatic pressure. Minimize slab penetrations where possible, and where floor drains are required, specify appropriate waterproofing and backflow prevention at each location.
• Removable Elements – Design exterior railings, equipment screens, and secondary structures as removable, both for operational flexibility and for rapid storm preparation.
• Accessible Door Widths – Design all primary entry points wide enough to accommodate the largest equipment the building is likely to receive over its lifespan.

The most enduring resilience projects are those that are well-loved and integrated into the character of a place. Using appropriate scale, mass, form, and materiality ensures that a building can withstand storms and time while fitting seamlessly within its surrounding context. Resilience is not just an engineering achievement, but a design one as well.

Key Considerations

• Study the Local Vernacular –Document the forms, materials, colors, and details of the existing built environment before designing. Communities near the water have evolved their architecture in response to the same conditions you are designing for.
• Mimic, Don’t Copy – Use similar roof forms, siding materials, and window proportions, but translate them through the lens of the building’s functional requirements. The goal is to feel at home in the neighborhood, not to imitate it literally.
• Use Locally Maintainable Materials – Waterfront communities may have limited access to specialty contractors and materials. Specify systems that local tradesmen can maintain and repair over the life of the building.
• Connect to the Water – Buildings in waterfront communities should orient toward the water, not away from it. Design outdoor spaces and views that celebrate the waterfront environment rather than treating it as a hazard to be hidden from.
• Design the Landscape – Incorporate bioretention areas, rain gardens, vegetated swales, and permeable pavers throughout the site to manage stormwater through natural processes. These features reduce runoff volume, filter pollutants, and improve long-term site performance during heavy rainfall events.