Lighting the lamp

Greenwood Industries restores the roof system on Boston's TD Garden

  • An aerial shot of TD Garden's new roofPhoto courtesy of Greenwood Industries Inc., Millbury, Mass., and Sika Sarnafil, Canton, Mass.
  • A worker's view from TD Garden's rooftopPhoto courtesy of Greenwood Industries Inc., Millbury, Mass., and Sika Sarnafil, Canton, Mass.
  • The completed PVC roof systemPhoto courtesy of Greenwood Industries Inc., Millbury, Mass., and Sika Sarnafil, Canton, Mass.

Home to six-time NHL Stanley Cup Champion Boston Bruins and 17-time NBA Champion Boston Celtics, Boston's TD Garden has hosted more than 30 million fans since opening in 1995. About 3.5 million people pass through TD Garden's doors each year to see the arena's famous tenants, as well as world-renowned concerts, family shows, wrestling bouts, ice shows and other events. The structure also houses the Massachusetts Bay Transportation Authority's (MBTA's) North Station, which has subway and commuter trains arriving and departing throughout the day.

Open year-round, the 19,600-seat arena is equipped with three private restaurants, 90 executive suites and 1,100 club seats, and it boasts a multimillion dollar high-definition video scoreboard with 360-degree LED technology. In 2009, an LED energy-efficient lighting system was added to the building's exterior.

The arena has been recognized by many organizations as one of the top arenas in the U.S. In 2006, arena industry publication Venues Today ranked TD Garden the No. 3 arena in the U.S. In 2007, TD Garden was selected as a finalist for the National Sports Achievement Award. In 2008, TD Garden received the Environmental Protection Agency's Green Power Leadership Award. And in 2009, TD Garden was nominated for Sports Facility of the Year by Street & Smith's SportsBusiness Journal.

Down for the count

In 2010, TD Garden's roof system reached its serviceable life expectancy and required replacement.

"We had been chasing drops for 15 years," explains Jason Beckett, director of operations for building owner Delaware North Companies Inc., Boston. "TD Garden can't tolerate roof leaks; we can't have anything interfere with a game or event or spoil the experience for the fans."

Delaware North Companies commissioned Wessling Architects Inc., Quincy, Mass., to design the new roof system. The owner and architect selected Greenwood Industries Inc., Millbury, Mass., as the roofing contractor for the project to replace the various roof and gutter systems during a two-year phased project timeline between June 2010 and June 2012; the project took place during the Bruins' and Celtics' off seasons.

First quarter

The first phase involved applying Sika Sarnafil's Sikalastic RoofPro Liquid Coating on the 10,317-square-foot gutter system in conjunction with parapet wall reconstruction and masonry thru-wall flashing replacement on the building's north and south sides. A 150-foot exterior stair tower provided daily access to the structure's 12 roof levels.

The second phase involved replacing the barrel-design roof, but work had to be delayed for a somewhat unexpected but welcomed reason—the Boston Bruins progressed to the playoffs and won the Stanley Cup, extending their season well into spring 2011.

"It was an unusual predicament for me," says David Klein, president of Greenwood Industries. "I was rooting for the Bruins to go all the way, but that meant my start date kept getting pushed back."

Keep the ball rolling

When work resumed in late June, Greenwood Industries began the tear-off process. About 113,000 square feet of existing mechanically attached PVC membrane and insulation were removed from the barrel-design roof down to the steel deck. Greenwood Industries removed about 80 to 100 roofing squares each day. The insulation was recycled, and Sika Sarnafil recycled the PVC into new roof membrane products.

SECUROCK® gypsum-fiber roof board first was installed on the steel deck followed by a continuous

Sarnavap self-adhering 32-mil-thick SBS polymer-modified bitumen vapor retarder. Four inches of insulation then was installed over the vapor retarder.

Given TD Garden's status as a Boston skyline landmark, the barrel roof design was paramount. Wessling Architects selected Sika Sarnafil's 80-mil-thick Rhino-Bond white PVC roof membrane. OMG Roofing Products' RhinoBond electromagnetic induction welding system was selected as the membrane attachment system to secure the insulation and PVC membrane to the roof deck. With a RhinoBond system, fasteners are located across the roof deck area in a grid pattern, rather than placed in rows in the membrane seams, to distribute the wind-uplift loads more evenly. Using this system allowed the 20-person crew to install 15,000 to 25,000 square feet of PVC membrane each day.

The barrel roof design includes visible truss caps spaced about 40 feet apart. Sika Sarnafil custom manufactured 80-mil-thick PVC membrane to 80-foot lengths to minimize the exposed seams and ensure the vertical seams joined under the truss caps, which Greenwood Industries custom fabricated using 80-mil-thick aluminum coated with a gray Sika Sarnafil PVC membrane.

A two-piece flashing also was used to ensure the watertight integrity of the truss-cap system.

On the sideline

Despite the late start, Greenwood Industries was on track to finish the roof system installation three weeks early. However, the arrival of Hurricane Irene on Aug. 27, 2011, threatened progress.

"We spent three days demobilizing equipment, removing portable restrooms and materials from the roof, and securing them on the ground to prepare for Irene," Klein says. "We lost almost a week of work because of that storm."

All hurricane preparations were performed successfully and without cost to the building owner.

Teamwork prevails

Despite numerous challenges, the roof was completed on time and on budget, thanks in large part to teamwork.

"There was tight communication with the entire design team, and we were all in tune to what was going on," says John Karman, senior project manager for Wessling Architects. "We shared mock-ups, had OMG Roofing Products and Sika Sarnafil representatives on-site, and did pull-tests together—it definitely was a team effort."


In addition to a compressed construction schedule because of the playoffs, work had to be completed without interruption to the daily operations of the MBTA North Station and the facility's event schedule. Greenwood Industries took every precaution to ensure the integrity of the building envelope and safety of the general public and millions of fans visiting the Boston landmark.

"Greenwood Industries' superior workmanship, extensive resources and professionalism resulted in a highly successful project," Karman says.

For its exceptional efforts on TD Garden, Greenwood Industries earned First Place for Sika Sarnafil's 2011 Contractor Project of the Year in the Low-slope category.

"Creating a lasting monument for the citizens of New England where people go to watch events almost every night of the week is the most rewarding part," says Matthew Brown, chief financial officer for Greenwood Industries. "Seeing your workmanship on national television every time the Bruins or Celtics compete for their respective championships is truly satisfying."

Like the sports teams beneath it, TD Garden's new roof system survived Hurricane Irene and continues to perform well. The TD Garden stands as a monument, museum and home to NBA and NHL champions, and now it stands as a monument to teamwork and excellence in the roofing industry.

Chrystine Elle Hanus is Professional Roofing's associate editor and NRCA's director of communications.

Project name: TD Garden
Project location: Boston
Project duration: June 2010–June 2012
Roof system type: PVC
Roofing contractor: Greenwood Industries Inc., Millbury, Mass.
Product manufacturers: Sika Sarnafil, Canton, Mass.; USG Corp., Chicago


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