PLUMBING SERVICES
Sanitary & Waste
Systems
Roof drainage, overflow, and site connection production support coordinated with your engineer’s
hydraulic design.
Our Founding and Mission
Introduction
NexMEP Global LLC supports U.S. MEP consulting firms with storm drainage system production, developing roof drain layouts, leader and conductor piping routing, and overflow system documentation from your engineer’s hydraulic design and the roof drainage strategy established for the project. Our team carries this detailed layout work through each design phase while your licensed engineers retain full authority over drainage strategy, pipe sizing methodology, and code compliance approach.
We work from the roof drain layout, rainfall intensity data, and overflow design your engineer provides, producing coordinated drawings and calculation backup that reflect that design intent without introducing independent assumptions about drainage capacity.
DESIGN ACCURACY & COMPLIANCE
Why This Service Matters
Storm drainage systems are sized to handle rainfall events specific to the project’s geographic location, and undersized or poorly coordinated systems can result in roof ponding, structural overload, or water intrusion during design storm events. Primary and secondary (overflow) drainage systems must be documented clearly and kept separate, since code officials routinely verify that overflow protection is present and correctly sized independent of the primary system.
Because roof drain locations must be coordinated with structural roof framing, architectural roof design, and rooftop mechanical equipment, and because leader piping often routes through the same shafts as other systems, storm drainage benefits from the same level of coordination attention as any other pressure or gravity piping system in the building. On projects with a rooftop amenity deck or mechanical yard, roof drainage design also has to account for a more complex roof geometry than a simple flat roof, adding another layer of coordination between the plumbing layout and the architectural roof plan.
Our Capabilities
Roof Drain Layouts
Coordinated placement of primary and overflow drains aligned with architectural roof low points.
Leader & Conductor Routing
Vertical leader routing through building shafts coordinated with adjacent MEP systems.
Primary & Overflow Separation
Clear visual and systemic isolation of primary and secondary (overflow) drainage runs.
Multi-Tiered Roof Drainage
Layout solutions for multi-level roofs, setback conditions, and complex amenity decks.
Area & Site Integration
Documenting area drains, site connections, and tie-ins to civil storm utility networks.
Industrial Zoning Layouts
Structuring drain patterns into logical zones aligned with structural framing bays for large footprints.
Calculations
Engineering Calculations
Calculation methodology built for accurate, traceable HVAC equipment sizing.
Rainfall Intensity & Leader Sizing
Roof drain, leader, and horizontal drain sizing based on contributing roof area, slope, and local rainfall intensity tables.
Independent Overflow Sizing
Sizing verification for secondary overflow systems calculated strictly independent of the primary drainage network.
Calculations
Systems We Support
Ventilation-related calculation support includes outdoor air rate compilation.
Conventional Gravity Systems
Standard roof drain and gravity leader piping layouts.
Siphonic Drainage Systems
Engineered high-velocity systems modeled per manufacturer software.
Scuppers & Spillways
Perimeter wall scupper and overflow scupper documentation.
Civil Site Interconnections
Invert-matched connections to civil site utilities and retention basins.
Multi-Level Roofs & Setbacks
Combined downstream leader sizing for varied roof elevations.
Amenity Decks & Equipment Yards
Drainage solutions for complex roof geometries and mechanical yards.
Our production support encompasses traditional and engineered storm systems, ensuring absolute precision between building discharge points and civil utility tie-ins.
Calculations
Software, Workflow & Coordination
Rigorous backup calculations formatted directly for permit submission and QA/QC documentation.
Software & Production Workflow
Storm piping is modeled in Revit MEP utilizing your firm’s standards and slope parameters. Workflow incorporates dedicated verification steps to ensure primary and overflow networks remain strictly separated, with continuous tracking against structural roof framing updates.
Revit & AutoCAD Coordination
Drain positions are cross-referenced with structural roof framing, low points, and rooftop equipment via Navisworks. We cross-check invert elevations and discharge tie-in points against civil engineering drawings to eliminate site-line discrepancies.
Calculations
Systems We Support
Expertise across diverse equipment lines, hybrid configurations, and complex Electrical setups.
Storm Drainage Roof Plans
Leader Riser Diagrams
Drain Schedule Packages
Calculation Backup Reports
Need Coordinated Storm Drainage Production Support?
Partner with NexMEP Global LLC for clash-free leader routing, roof layouts, and civil tie-in accuracy.
Our Core Philosophy
Typical Project Types
Commercial & Office
Office towers, corporate developments, and commercial properties.
Large-Footprint Industrial
Warehouses and industrial plants structured into bay drainage zones.
Multi-Family & Hospitality
Multi-family developments, mixed-use complexes, and hotels.
Education & Healthcare
K-12 schools, higher education campuses, and healthcare facilities.
Calculations
QA/QC Process
A rigorous, multi-tiered review structure ensuring accurate, clear, and error-free submittals.
Primary/Overflow Separation Audits
Confirming secondary overflow drains and scuppers are documented to activate only when primary limits are exceeded.
Civil Elevation Verification
Verifying building discharge elevations match civil utility connection points and detention inverts.
Drainage Area Cross-Checks
Independent secondary reviews checking that total roof area per leader matches assigned plan areas.
Why NexMEP Global LLC?
NexMEP Global LLC brings a dedicated production team with practical experience across standard and specialty ventilation systems, a consistent U.S. code and standards focus, and a multi-level QA/QC process that reduces rework during your engineer’s review cycle.