Roof Deck & Terrace Waterproofing
Leaks under a terrace are waterproofing leaks. We lift the pavers or decking, rebuild the membrane and drainage beneath, and put the surface back.
Learn moreLiquid-Applied roof waterproofing across New York, NY
Where sheet membranes need dozens of cut pieces and seams, a reinforced liquid membrane goes on as one continuous layer. It suits roofs crowded with equipment, setbacks and awkward penetrations.
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- Reinforced liquid membranes
- Built for crowded roofs
Quick answer: Liquid-applied roof waterproofing is a resin, often PMMA or polyurethane, applied in coats with a reinforcing fleece to form one continuous membrane. In New York, NY it is used where roofs are crowded with dunnage, pipes and equipment, on setbacks and terraces, and to flash details sheet membranes handle poorly.
What the job involves
Why liquid works where sheets struggle
A sheet membrane has to be cut and seamed around every leg of dunnage, every pipe and every railing post. Each cut is a seam, and each seam is a place to leak. A liquid membrane flows around the object and cures into one piece with no seams at all.
The tradeoff is that the result depends heavily on surface preparation, weather and film thickness. The substrate has to be clean, dry and primed, and each coat has to go on at the thickness the maker specifies, with the fleece fully embedded.
Your options
Liquid membrane or sheet membrane?
| Factor | Liquid-applied | Sheet membrane |
|---|---|---|
| Seams | None. Cures as one piece. | Lapped, taped or welded seams. |
| Crowded roofs | Flows around legs and pipes. | Many cut pieces and flashings. |
| Weather | Needs suitable conditions while curing. | Less sensitive, depending on the system. |
| Large open roofs | Usually costs more per square foot. | Usually the more economical choice. |
Cost factors
What liquid waterproofing costs depend on
System chemistry
PMMA, polyurethane and other resins differ in price and cure time.
Number of details
Every leg, pipe and curb adds labor.
Surface preparation
Cleaning, repairs and primer are a large share of the work.
Film thickness
Thicker systems use more material.
Area and access
Small setback roofs carry high access costs per square foot.
Weather
Some systems need dry, mild days to cure properly.
Variations of the job
Where liquid-Applied systems earn their place
Roofs crowded with equipment
Steel dunnage, condensers, exhaust fans and conduit leave little open roof. A liquid membrane seals around every leg and bracket without a pile of cut-and-seamed pieces.
Setback roofs
The small roofs at building setbacks sit against walls, windows and doors. Liquid systems turn up walls and under thresholds where sheet goods are hard to finish neatly.
Detail work at penetrations
Even on sheet membrane roofs, liquid flashing is often the cleanest way to seal tight pipe clusters, replace old pitch pockets and close odd-shaped penetrations.
Local conditions
Pails instead of rolls above narrow streets
In Manhattan, getting material onto a roof is part of the job, with dumpster permits, early-morning sidewalk staging and sometimes a crane for heavy rolls. Liquid systems arrive in pails that can go up a stairwell or freight elevator, and they leave little tear-off debris when applied over a sound substrate. On crowded roofs above narrow streets, that alone can make them the practical choice.
What is included
What a liquid-Applied job should include
- Moisture check of the existing roof
- Repair of loose or blistered areas before coating
- Primer specified for each substrate
- Reinforcing fleece at every detail
- Field fleece where the system requires it
- Wet film thickness checked as each coat goes on
- Proper terminations at walls, doors and thresholds
- Protection of equipment and windows from drips
- Photos of the details before and after
How it runs
How a liquid membrane goes on
- 1
Prepare the surface
Loose material removed, repairs made, surface cleaned and dried.
- 2
Prime
Primer matched to the substrate: membrane, concrete, metal or masonry.
- 3
Reinforce details
Fleece set in resin at every leg, pipe, curb and wall.
- 4
Base coat with fleece
Field fleece embedded in the base coat where the system calls for it.
- 5
Top coat and check
Top coat applied and thickness checked before cure.
Makers of reinforced liquid membranes and liquid flashing systems found on New York roofs.
Kemper SystemSiplastSopremaTremcoSikaGAF
Questions we hear
Liquid-Applied waterproofing questions
No. A coating restores the surface of an existing roof. A reinforced liquid membrane is a waterproofing system in its own right, built thicker with fleece embedded in the resin.
Often, if the existing roof is dry and sound and the system is approved for that surface. Wet or loose areas are removed and repaired first.
It depends on the chemistry. Some PMMA systems cure fast enough to walk on the same day, others need longer, and the schedule follows the system's cure time.
Some systems can be applied in cold weather and some cannot. The maker's temperature and moisture limits set the schedule.
Yes, especially where the membrane has to turn up walls and under doors. Pavers or decking over it need protection so they do not wear the surface.
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Call for a roof survey and a liquid-applied waterproofing plan.