Waterproofing Services
Waterproofing
Building envelope waterproofing assessment and repair coordination for plaza decks, roof terraces, below-grade foundation walls, and façade sealant systems on New York City buildings. Post & Lintel supports building owners, co-op and condo boards, and property managers across Manhattan, Brooklyn, Queens, the Bronx, and Staten Island in identifying water infiltration sources and coordinating waterproofing repair before conditions affect structural elements, interior finishes, or façade integrity.
Water infiltration is one of the most common — and most frequently deferred — sources of building deterioration in New York City.
Waterproofing failures rarely announce themselves. A cracked sealant joint, a failed plaza deck membrane, or a hairline gap at a below-grade wall can go unnoticed for years while moisture works its way into structural steel, masonry, and interior spaces. By the time staining or spalling becomes visible, the underlying condition has often been active for some time.
Waterproofing findings frequently surface during other inspection work — a FISP critical examination noting façade water-tightness, or a parapet inspection identifying failed coping sealant. Post & Lintel coordinates waterproofing assessment as both a standalone service and as a natural follow-on to façade and structural inspection findings.
Waterproofing System Types
Building envelope waterproofing covers several distinct systems, each with its own failure modes, testing methods, and repair approach.
Plaza & Terrace Decks
Waterproofing membranes beneath plaza pavers, terraces, and roof decks over occupied space below. Failures here often present as interior ceiling staining or active leaks in the space beneath the deck.
Below-Grade & Foundation
Waterproofing at foundation walls, cellar spaces, and any structure below grade. Conditions here relate to hydrostatic pressure, drainage, and membrane continuity at wall-to-slab transitions.
Façade Sealant & Joints
Sealant systems at expansion joints, window perimeters, spandrel panels, and parapet coping. Sealant has a limited service life and is a recurring maintenance item independent of the underlying wall condition.
Conditions We Commonly Identify
Waterproofing assessments frequently identify the following conditions, though the specific scope depends on building age, construction type, and prior maintenance history.
- Failed or missing sealant at expansion joints
- Deteriorated plaza deck membrane
- Ponding water on roof or terrace surfaces
- Hydrostatic pressure at below-grade walls
- Cracked or displaced coping joints
- Window perimeter sealant failure
- Deteriorated through-wall flashing
- Efflorescence and interior staining
- Corroding embedded metals from moisture exposure
- Failed pedestal paver drainage systems
- Cracked or settled foundation wall coatings
- Improperly sloped drainage at deck surfaces
Signs You May Need a Waterproofing Assessment
Waterproofing failures are often identified only after a secondary symptom appears elsewhere in the building. Property managers and building owners in New York City commonly report the following before scheduling an assessment:
- Ceiling staining on a top-floor apartment or office
- Active leak following heavy rain or snowmelt
- Basement or cellar wall dampness after storms
- Ponding water on a roof deck or terrace
- Efflorescence (white mineral deposits) on masonry
- Peeling paint or bubbling drywall near exterior walls
- Musty odor in below-grade or ground-floor spaces
- Visible gaps at window perimeters or expansion joints
- Loose or cracked plaza pavers
- Recurring leaks in the same location after prior patch repairs
Any of these conditions can warrant a waterproofing assessment, particularly if a prior patch repair has not resolved the underlying issue. Recurring leaks after a patch repair often indicate the water entry point has not been correctly identified, rather than that the repair failed outright.
How Waterproofing Assessment Works
Waterproofing assessment typically follows a coordinated sequence from initial observation through repair close-out.
Permits for Waterproofing Repair Work
Whether a waterproofing repair requires a New York City Department of Buildings permit depends on the scope of work. Minor sealant replacement and localized coating repairs are frequently classified as minor or exempt from filing, while structural waterproofing membrane replacement, plaza deck reconstruction, and below-grade waterproofing tied to foundation work typically require a filed permit application (commonly a PW1 or Alt-CO filing) with signed and sealed drawings from a licensed design professional.
Coordination With Other Filings
Waterproofing repair work frequently overlaps with other active filings on a building. A plaza deck waterproofing project may require coordination with an active Local Law 11 SWARMP repair timeline; below-grade waterproofing adjacent to a retaining wall may fall under Retaining Wall inspection findings; façade sealant repair at parapet coping is often scoped alongside Parapet Inspection remediation. Post & Lintel coordinates waterproofing permitting alongside these related filings where applicable, rather than treating each as an isolated project.
Licensed Contractor Requirements
DOB-filed waterproofing work must be performed by a licensed contractor in accordance with the filed scope of work. Post & Lintel supports contractor bid review and scope verification to confirm proposed work aligns with the permitted filing.
Post & Lintel Waterproofing Services
Post & Lintel supports building owners and property managers across waterproofing assessment and repair coordination. Field observations and documentation may be performed by trained personnel; regulated evaluations and DOB filings are performed by appropriately licensed professionals.
- Water infiltration source assessment
- Plaza and terrace deck evaluation
- Below-grade and foundation assessment
- Façade sealant and joint evaluation
- Moisture mapping coordination
- Flood testing coordination
- Repair scope and sequencing
- DOB filing for qualifying repair work
- Contractor bid and scope review
- Construction observation support
- Coordination with FISP and parapet findings
- Multi-system repair planning
Who We Work With
Post & Lintel has supported waterproofing assessment across a range of building types and ownership structures throughout New York City's five boroughs.
Frequently Asked Questions
How do I know if my building has a waterproofing problem?
Common signs include interior ceiling or wall staining, active leaks after rain, efflorescence on masonry, ponding water on decks or terraces, and visibly failed or missing sealant at joints and window perimeters.
Does waterproofing repair require a DOB permit?
It depends on the scope. Minor sealant and localized membrane repairs are often minor in scope, while larger deck waterproofing, structural repairs, or below-grade work typically require a filed DOB permit with signed and sealed drawings.
Is waterproofing related to my FISP inspection?
Often, yes. FISP critical examinations include a water-tightness assessment as part of the façade review, and conditions such as failed caulking or coping sealant identified during a FISP inspection frequently fall under waterproofing repair scope.
How is the source of a leak identified?
Source identification typically starts with field observation and history review, and may involve testing methods such as flood testing or moisture mapping when the entry point is not visually apparent, particularly for below-grade or deck conditions.
How long does a waterproofing repair take?
Timelines vary significantly based on system type, scope, weather-dependent application windows, and whether DOB filing is required. Sealant repairs can often be completed in a matter of days; deck or below-grade membrane replacement is a longer undertaking.
What does a waterproofing assessment cost?
Assessment fees vary based on building size, the number of systems involved, and accessibility. Repair costs vary separately based on the scope of work identified. A specific estimate depends on the individual building and conditions found.
What's the difference between waterproofing and roofing?
Roofing refers to the weatherproofing system at the roof plane itself, such as membrane, shingles, or built-up roofing. Waterproofing is a broader category that also includes plaza decks, below-grade walls, and façade sealant systems — some of which sit below or beside a roof, not on top of it.
Can a recurring leak mean a prior repair was done incorrectly?
Not necessarily. A recurring leak in the same area often means the original water entry point was not correctly identified, since water can travel laterally along a structural element before appearing at a visible surface far from the actual source.
Do co-ops and condos need waterproofing assessments regularly?
There is no citywide law requiring periodic waterproofing inspection on its own, unlike FISP. However, boards commonly commission an assessment when a leak is reported, during capital planning, or when façade or roofing work is already underway, to address related envelope conditions at the same time.
Noticing signs of water infiltration? Reach out to discuss an assessment for your building.
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