Roof & Facade Waterproofing
Most leaks in a New York building aren’t a single hole. They’re a failed detail: a sealant joint, a flashing at a parapet or skylight, a lintel or shelf angle with no working waterproofing behind it, or a balcony slab letting water into the structure. Altius CM waterproofs roofs and facades at those details, as a standalone job or as part of a larger facade or roofing restoration.
Where does the water actually get in?
- Sealant and caulk joints at windows, panels and expansion joints, which wear out long before the masonry does
- Lintels and shelf angles, where corroding steel and missing flashing let water into the wall and crack the brick in front of it
- Roof-to-wall transitions: counterflashing at parapets, curbs and skylights
- Balconies and terraces, where a worn traffic coating lets water reach the slab edge
- The roof membrane itself, once it has outlived its system
What do we install?
- PMMA (polymethyl methacrylate) liquid-applied waterproofing and flashing at skylights, balconies, back-up walls and complex penetrations. See PMMA waterproofing in NYC.
- Liquid-applied and reinforced fluid-applied roof membranes, with liquid flashings and sheet metal
- Full sealant and caulk replacement, from window perimeters to whole-building recaulks
- Expansion joint replacement (Emseal)
- Lintel and shelf angle replacement with waterproofing
- Balcony traffic coatings (for example, Terapro 220) after concrete repair
- Counterflashing at perimeters and parapet walls
How does a waterproofing job run?
- Find the failure. We trace the leak to a detail rather than treating the stain inside.
- Choose the system. Match the material to the substrate and the detail: PMMA where it has to bond to many surfaces, sealant where joints need to move, membrane where the whole roof is done.
- Access. Roof work from the roof, wall work from suspended scaffolds or rope access. See access and scaffolding.
- Install and detail. Terminations, laps and transitions are where waterproofing fails, so that’s where the time goes.
Which NYC rules apply?
If the work is a full roof deck or roof assembly replacement, Local Laws 92 and 94 of 2019 require a sustainable roofing zone (solar, green roof or both) on most of the roof. A repair or partial job doesn’t trigger it. Source: NYC DOB, Local Laws 92/94, explained in our Local Laws 92 and 94 guide. On buildings over six stories, failed sealant, lintels and balcony slabs are exactly what a FISP inspector documents, so waterproofing is often part of a facade repair scope driven by Local Law 11.
Our work in this area
- 111 Hudson Street: PMMA waterproofing at existing round skylights, a 400 SF PMMA flashing allowance, and new counterflashing at perimeters and parapet walls.
- Kips Bay Complex: PMMA back-up wall flashing replacement, 3,000 LF of Emseal expansion joint, 80,000 LF of sealant, and 460 balconies repaired and coated with Terapro 220.
- 3935 Blackstone Avenue: 20,000 LF of sealant replacement, 1,000 LF of lintel restoration and waterproofing, and traffic coating on every balcony.
- 5 East 22nd Street: 10,000 LF of shelf angle replacement and waterproofing, and 30,000 LF of sealant replacement.
Frequently Asked Questions
Is a whole-building recaulk worth it, or should we just patch the leaks? If the sealant has reached the end of its life across the building, patching chases one leak to the next. Several of our projects, including 3935 Blackstone Avenue and 5 East 22nd Street, replaced sealant across the entire structure.
What is PMMA, and when is it used? A fast-curing, liquid-applied waterproofing that bonds to many substrates. It’s used at details where sheet goods struggle, such as skylights, balconies and penetrations.
Does a waterproofing job trigger the green roof requirement? Only a full roof deck or roof assembly replacement does. Flashing, sealant and partial repairs don’t.
