commARCH - July August 2015

Page 34

PROJECT

roofing

High-In-The-Sky Roofing Kemperol resin membrane seals the roof at New York’s One World Trade Center. Challenges involved with roofing/ waterproofing a high-rise are magnified with height. One World Trade Center in New York is protected with a roofing system from Kemper System America. Photo Credit: Polina Ryazantseva| Dreamstime.com

A

fter almost a decade of construction,

for the main roof and louver areas on lower floors

New York’s $3.9 billion One World

that were enclosed on three sides. The liquid-ap-

Trade Center (1 WTC) opened its doors

plied resin membrane systems are reinforced with

in 2014. The challenges involved with roofing/wa-

Kemperol 165 fleece and conform around any

terproofing a high-rise are magnified with height,

shape. Penetrations, drains, curbs, and perimeters

and at an official height of 1,776 ft., 1 WTC (for-

were also sealed with the system and then over-

merly Freedom Tower) offers some valuable les-

lapped by the membrane in the larger expanse to

sons. The 408-ft. spire atop 1 WTC weighs more

provide durable waterproofing protection.

than 750 tons and makes the skyscraper 326 ft. tall-

The work on the main roof membrane began in

er than the Willis Tower in Chicago, making it the

mid-June 2014 and was completed in mid-October.

tallest building in the United States.

At nearly a third of a mile high, the roof weather

With most new construction the building enve-

could be a surprise. “A lot of times when it was a

lope, including the roof, is completed first. In this

cloudy day on the ground, it could be foggy. Or if

case, the main roof was one of the last structural

it was foggy on the ground, it could be raining

items to be completed. Steve Guarino, general su-

when we got to the top. But the heat was not too

perintendent for waterproofing contractor, The Jo-

bad, and there was no sweltering hot weather,” re-

bin Organization Inc., Farmingdale, NY, shared

ported Guarino.

some experiences working on the iconic structure while, as he put it, “A billion eyes were watching.”

GETTING THERE

The Jobin Organization, originally established

One obvious challenge in waterproofing a high-rise

as Jobin Waterproofing Inc. in 1968, is a major

is simply getting materials to the roof. “By the time

presence in the New York construction market in

we got to the roof, the outside hoist had been taken

areas such as roofing, waterproofing, exterior resto-

down, which might have saved a little time,” Gua-

ration, and construction management. The com-

rino said. “But with the Kemperol system, there’s

pany is a Kemper System America Inc., West Sene-

no heavy equipment, so we were OK. The heaviest

ca, NY, certified applicator and has completed

tool we used was a hand mixer for the resin.”

many projects with the cold-fluid-applied reinforced membrane systems.

The trek to the 105th floor could take as much as two hours because of all the trades on the site. The Jobin Organization crew would bring materi-

FLEXIBLE SOLUTION

als up through the building on the elevator cars,

The 1 WTC main roof is about 19,000 sq. ft. “One

many times on Saturdays and Sundays to have all

of the primary reasons we won the bid with the

the required materials ready to go.

Kemperol system was all the exposed steel and

Guarino explained, “We would take materials

many penetrations. There were hundreds, maybe

from the loading dock to the main-floor elevators,

300 or 400 penetrations on the main roof. That

up to [floor] 102, and then transfer to 105. The in-

included the structure for the three cooling tow-

sulation and cement board were loaded on 4 ft. x 4

ers above us, the spire, as well as the everyday vent

ft. skids and some stored on 104 during the job.”

pipes, drains, conduits, plumbing, and other pip-

Also easy to transport, the Kemperol resin is pack-

ing. There were no areas bigger than about 10 ft.

aged in 2 1/2- and 5-gal. containers, and the fleece

x10 ft. without some penetration,” said Guarino.

reinforcement in rolls to 41-in. wide.

The Jobin Organization ran a 15- to 20-person

Above Left. Huge bolts at the base of the spire were among hundreds of exposed roof details protected with the Kemperol system. Above Right. What appears to be a simple white coating is actually the top layer of the Kemper system. The membrane is fleece-reinforced and forms a seamless surface that is unaffected by standing water, snow, or ice. It also resists chemicals, corrosives, and UV light. 32

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JUL/AUG 2015

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crew on the job. “There were so many configura-

JOB-SITE COORDINATION

tions that needed waterproofing–curbs, drains,

Kemper System specialists were on-site weekly to

HVAC, beams, nuts and bolts, and around the

inspect and advise on the job. In addition, a build-

base of the spire. There was so much steel, some-

ing-envelope consultant photographed progress

times we were ‘bumping heads’ with our hardhats,”

daily to provide feedback to the A/E/C manage-

continued Guarino.

ment team.

For the main roof, insulation, and pre-primed

There were conversations with the manage-

cement board were first installed and adhered with

ment consultants every morning to make sure ev-

beads of foam adhesive. The cement board was

erything was running smoothly, Guarino said. But

staggered in a joint pattern over the insulation and

there was no cell phone service available on the

sealed at the seams with beads of NP1 polyure-

roof during construction because of the thickness

thane sealant. The seams of the cement board were

of the slab. So more-urgent messages were often

also sealed with 4-in. continuous stripping plies of

relayed a couple of floors down the old-fashioned

Kemperol.

way–by walkie-talkie.

The Kemperol resin membrane was specified

“The biggest challenge was coordination on the


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