Every repair job has unique challenges, so the intricacies found in high-rise repair projects often give contractors little pause. High-rise projects can encompass everything from apartments and condominiums to office buildings and industrial structures. They are similar to other residential or commercial projects, except that much of the work is performed well above ground. Therefore, factors common to any repair job—such as gaining access to work areas, building relationships with owners and tenants, and maintaining a good safety record—tend to take on heightened importance.
One of the biggest challenges to any high-rise repair project is securing access to work areas. Swing stages are generally the best option, as they allow you to concentrate access only on the areas that need repair. However, this type of rigging might not be feasible or efficient on some types of structures. In which case, scaffolding or mast climbing work platforms are erected over the entire structure to access to work areas. Gaining access can be one of the most expensive and difficult aspects of this type of job, particularly if only a few small repairs are needed. Don't be tempted to cut corners in quality to make up for the cost of access; that could come back to haunt you, especially if the repairs you make are under warranty.
The erection of a swing stage can be a real challenge. Stirrups connected to large electric motors typically are found at the ends of the swing stage platform. The motors have traction pulleys that run up and down 5/16-inch-diameter wire cables. The cables are attached to beams on the roof of a structure and the beams are counterweighted with a sufficient factor of safety to prevent overturning. The beams then must be tied back to the structure. These steps require a good deal of knowledge about rigging, spreading loads on a roof with limited capacity, choosing the right amount of counterweight, and other safety concerns. The rigging system should be designed by a qualified person and installed, maintained, and changed as needed by a competent person.
At the start of a job, all beams, weights, tie-back cables, drop cables, and roof protection need to be taken to the roof by elevator, crane, or hoists. Sometimes this equipment must be carried up by hand, piece by piece, as the freight elevators often stop short of the roof. Once the materials are on the roof, the suspension systems can be set up and the drop cables can go over the side of the building to the swing stage at the bottom of the building. An electric cord powers the motors. Additional concerns may need to be addressed, such as vehicular traffic, foot traffic, lavish landscaping, glass atriums, or lower roof structures.
On large repair projects, the planning and sequencing of the work also is a major factor. High-rise projects often have 10 to 20 different work tasks being performed at one time. The scope of work varies from job to job but can include tasks such as shoring, caulking, waterproofing, grinding, chipping, blasting, forming, and pouring occurring simultaneously. This level of multiple task management requires careful planning and execution. It is vitally important to thoroughly lay out a sequencing strategy during preproject planning meetings, allowing you to effectively manage the various crews and the timing of their tasks. For example, when repairing damaged concrete elements, the reduction in capacity resulting from reinforcement section loss or the removal of concrete during the repair must be considered. Shoring must be designed and installed prior to the removal of concrete, while repairing cantilevered reinforced concrete balconies, beams, or columns before the removal will further weaken these elements during demolition. Additionally, protective materials on the building or ground must be installed prior to concrete demolition. Such protection materials could include netting, plywood over windows, overhead protection of walkways and drive-throughs, or simple barricades and fencing. When working on balconies, pedestrian lock-outs should be installed at balcony sliding doors to prevent residents or hotel guests from entering work zones.
During the work sequence planning, it helps to be aware of the many factors that can affect productivity on the job. Even seemingly small details, such as the size of the work area, can have a huge impact. For instance, the difference between one large repair area and several small repair areas can affect everything from how many linear feet of sawcutting you'll have to do to how easy or difficult it will be to move equipment around the job or to what type of placement method you'll use to fill in the area once the repairs have been completed. Even the type of material you use will have an impact on how the job is planned. For example, will you mix prebagged material on-site, or will you use ready-mixed concrete that is pumped to the repair areas? How will you go about cleaning the reinforcing steel? Which type of coating is specified? These questions should be answered in the planning stages so they can be dealt with quickly onsite.
Of course, all the planning in the world can't prevent unforeseen circumstances from arising. Most contractors are prepared for the common problems—such as weather and disparities between plans and actual conditions—but these things can present even more of a challenge on high-rise projects. Like any other project, high-rise repair jobs are surveyed before work begins to determine the scope of the repair needed. However, more often than not, only a small percentage of the building is surveyed, and the remainder of the proposed work is extrapolated from that data—meaning that once the contractor gets onsite, they may find conditions to be very different than anticipated, such as finding hidden delaminations in the concrete. Other variables include substantially underestimating repair quantifies, mold within the exterior wall cavity, lead-based paint on balcony ceilings, or other components of the building. Because these unforeseen variables often can have a major impact on project factors such as time and cost, it's important to be upfront and honest with the owners during the planning stages. Failure to do so can have a damaging impact on the quality of your relationship.