The Houston skyline is a landmark that can be recognized by many afar. Multi-level buildings, high-rises and three major league sporting venues help to make up a very prominent downtown district. Two buildings at the center of downtown Houston’s central business district are One and Two Shell Plaza, which house the United States headquarters for Shell Oil Company.
At the midst of a construction boom in 1971, One Shell’s completion made it the tallest building in Houston at a height of 715 feet, or 50 stories. Two Shell was completed a year later to serve as additional office space and parking. It sits 26 stories high and is linked to Houston’s extensive tunnel system which leads to other major downtown office buildings as well as a variety of shops and restaurants.
It had been almost 20 years since the last major renovation for both buildings, and exterior maintenance was necessary. The windows and stone panels were damaged and the 30,000 square foot roof on Two Shell was experiencing numerous leaks. In order to completely update the Houston landmark, the ownership decided to replace the windows, roof, pedestrian plaza and a large portion of the panels, which would require multiple trades. Chamberlin’s extensive experience working on high rise buildings, gave D.E. Harvey, the general contractor, the confidence to award both the roofing and waterproofing portions of the work to Chamberlin.
Phase One: Window and Masonry Caulking
An extensive amount of work was required for both One and Two Shell Plaza. Phase one of the waterproofing portion began in January 2011 which consisted of replacing and caulking damaged travertine panels and windows.
Considering the height of the buildings, the work required a significant amount of rigging, scaffolding and overhead protection. Two Shell’s sequencing was completed one floor and elevation at a time to accommodate the building tenants and window contractor, Arrowall. The windows were replaced at night, since the building is occupied during the day, requiring Chamberlin to apply the sealants one floor at a time following closely behind Arrowall as they complete each level. This meant having a daytime rigging crew so that swing stages were set up for the night time caulking crew. Work being done at night required sufficient lighting for the men to see and also to safely complete the project. At the same time, Camarata Masonry was replacing damaged stone panels on multiple levels of both towers. Camarata contracted Chamberlin to caulk the stone joints as it was replaced.
Each building had its own dedicated Chamberlin crew to ensure work would be complete in a timely manner. One Shell had a special temporary swing stage system with a trolley that allowed Chamberlin to set the stages on the roof and rig each drop from the top of the building which made it easier to coordinate with WinCon Enterprises, the window contractor.
Working on a high rise office building poses challenges with ensuring all tools and equipment are securely tied off so as to prevent falls from the building during the course of work. This was accomplished by installing netting on the platforms and tethering the tools to the individuals while in use and to a tag line on the back of the platform while not in use.
Scheduling was a challenge when it came to working on two buildings with multiple crews and contractors. It was necessary to anticipate when work would be complete for each scope and when the next portion of work would need to begin.
“Our ability to execute all waterproofing scopes of work through multiple contractors and subcontractors has made Chamberlin’s role in this project unique,” said Chamberlin Waterproofing Operation’s Manager, Shane Hubbard. “There were different trades for each phase of work which required a lot of coordination.”
Phase Two: Plaza Entrance
Phase two began in October as soon as the exterior work was complete and will be worked on throughout the summer. The entire stone sidewalk entry on One Shell was removed and replaced with hot applied waterproofing and new pavers installed by Cangelosi Stone. This portion of the project is considered “tenant security renovation” because the new redesigned plaza will provide more space between vehicular traffic and the building’s pedestrian entrance.
In February of 2012, Chamberlin began the roof replacement process of Two Shell Plaza. Replacing a roof on a 26 story building requires innovative thinking to overcome the challenges that could potentially lie ahead. In order to address the challenges before they became obstacles, Chamberlin Roofing Project Manager, Marty Hensley, held a number of team meetings to coordinate procedures step by step. The team planned each action down to the detail, even knowing the exact time it took materials to be transported on the service elevator from level one to level 26. Due to high winds, the materials were strapped and banded together atop the roof. Once the original roof was removed down to the concrete deck and two and one-half inch insulation was in place, a cover board was installed and a base sheet was torched to it. The cap sheet and elastomeric coating were then installed for protection and energy efficiency. When the roof installation was complete, all counter flashings were replaced as well as the gravel guard on two penthouses. Approximately 800 linear feet of pre-fabricated coping was installed over the travertine around the perimeter of the roof. There were no parapet walls to protect Chamberlin workers from a potential fall hazard so crews were required to be 100% tied off at all times.
Chamberlin is scheduled to finish phase two by September 2013, making a total of 31 months working on One and Two Shell Plaza.
Waterproofing consultant, Curtainwall Design Consulting (CDC), performed inspections throughout each phase to ensure caulking installations met high quality standards.