Roof Drain, Storm Drain and Rain Leader Repair in NYC

A roof drain collects rainwater and snowmelt from a roof and sends
it into storm drainage piping. A storm drain stack — also
called a rain leader, roof leader, or interior leader — carries that water
down through the building to a storm drain, combined sewer, detention system, or
approved outlet. These systems matter a lot in NYC, where many buildings have flat
or low-slope roofs, parapets, setbacks, and interior storm piping. Problems show up
as roof ponding, ceiling leaks, water in walls, basement flooding, or water backing
up through floor drains during heavy rain. A key point up front: a roof leak
is not always a roof-drain problem — it may be a roofing membrane,
flashing, parapet, penetration, clogged drain, or cracked storm-stack issue, or a
combination, so the source should be confirmed before promising a fix.
This article is general information, not legal or engineering advice; confirm
your specific situation with a NYC Licensed Master Plumber.

Roof drainage components #

• Roof drain body + dome/strainer — collects roof water and keeps large debris out.
• Primary roof drain — the main drainage path, sized for design rainfall.
• Secondary / emergency roof drain and overflow scupper — backup drainage if the primary drain is blocked or overwhelmed (NYC Plumbing Code Ch. 11 addresses secondary roof drainage).
• Interior rain leader / storm drain stack — vertical storm piping inside the building (cast iron, PVC where permitted, copper, or galvanized).
• Exterior leader / downspout — storm piping down the outside of the building.
• Horizontal storm drain, yard/areaway drains, and combined sewer connection — carry stormwater to an approved discharge.
• Detention/retention system and backwater valve — control discharge rate and prevent reverse flow where required.

Roof drains serviced, storm stacks repaired #

Roof-drain service covers cleaning (removing leaves, roof gravel,
trash, sediment, and ice), storm-leader snaking or jetting, strainer/dome
replacement, drain-body inspection, camera inspection where access allows, leak
diagnosis, emergency storm clearing, and preventive seasonal maintenance.
Storm drain stack repair/replacement ranges from a spot repair (a
local crack, failed joint, or pinhole) to a section or full stack replacement for
corroded or repeatedly leaking piping, plus horizontal storm-line repair, roof-drain
connection repair, cleanout installation, backwater-valve review, and the
firestopping and wall/ceiling restoration needed to access concealed piping. In
older NYC buildings, storm stacks hide in walls, shafts, closets, and ceilings, so
water can travel along beams and insulation and appear far from the actual leak.

Common roof-drain and storm-stack problems #

• Roof ponding — clogged drain, bad slope, undersized drainage, or a blocked scupper; adds heavy water load to the roof.
• Ceiling leak during rain — roof membrane/flashing failure, a clogged drain, a cracked leader, or a failed roof-drain flashing.
• Leak from a pipe chase — a cracked storm stack, a failed joint, condensation, or a roof-drain backup.
• Basement floods during heavy rain — storm-line blockage, combined-sewer surcharge, a bad yard drain, or a backwater issue.
• Repeated clogs — a missing/broken strainer, nearby trees, roof gravel, or poor maintenance.
• Water backs up through a floor drain during rain — combined-sewer surcharge, a backwater issue, or a storm-line defect.
• Cracked storm pipe or drain odor — age, corrosion, settlement, or freeze damage; a dry trap or improper connection can cause odor.

NYC code, DEP, DOB, and permit requirements #

The 2022 NYC Construction Codes took effect November 7, 2022. NYC Plumbing Code
Chapter 11 governs storm drainage — roof drains, conductor/leader and
horizontal storm sizing, secondary/emergency drainage, cleanouts, backwater valves,
detention/retention, and discharge — and requires storm-water discharge to
follow DEP requirements. Roof-drain and leader sizing is based on projected roof area
and design rainfall, and code requires adding one-fourth of the area of vertical
walls that divert rain onto the roof/setback to the projected roof area for sizing
— important given NYC parapets, setback walls, and bulkheads. Storm drainage
systems also require cleanouts.
(2022 NYC Plumbing Code, Ch. 11)

Roof-drain cleaning is generally maintenance, but storm-drain pipe repair or
replacement is permit-sensitive: replacing storm stacks or interior leaders,
installing/relocating roof drains, adding secondary drains, installing cleanouts or
backwater valves, or altering storm drainage generally requires Licensed Master
Plumber supervision, DOB permits, and inspections. DEP is relevant when roof/storm
drainage involves storm-water discharge, combined sewers, private sewers/drains,
sewer backups during rain, or a Notice to Repair (owners are responsible for the
private sewer service line to the City main). Roof-drain problems often require
both roofing and plumbing judgment — a cracked stack is
plumbing, but a failed membrane or drain flashing is roofing — and DOT, LPC,
HPD, or DOHMH may apply depending on the work.
(NYC DOB)

When cleaning is not enough #

Cleaning may restore drainage, but repair or replacement may be needed when a roof
drain clogs repeatedly, a storm stack leaks during rain, or a camera shows cracked,
collapsed, bellied, or offset piping. A cracked or corroded drain body, a failed
roof-drain flashing/membrane connection, a missing or broken strainer, persistent
ponding after cleaning, missing or inadequate secondary drainage, no usable cleanout,
a mud-filled horizontal storm line, basement flooding during storms despite cleaning,
a floor drain that backs up in heavy rain, a suspected combined-sewer surcharge, old
cast iron with repeated leaks, or defective drains exposed during a roof replacement
all point beyond a simple cleaning — as does drainage tied into an improper or
undocumented connection.

Sources #

• 2022 NYC Plumbing Code — Chapter 11, Storm Drainage
• NYC DOB — Plumbing Permits
• NYC DEP — Sewer Backup
• NYC DEP — Stormwater