CGI – An effective and efficient method for repairing moisture damage in elevator pits by George Doukas

George Doukas, CGI Northeast Inc.

Water leakage in elevator pits poses a host of serious hazards that any property owner and facility manager will be eager to be rid of.

If water infiltrates an elevator pit, it can cause multiple problems from corrosion of structural steel supports to a complete breakdown/shutdown of the elevator’s electrical and mechanical operational system. Elevator pits are situated at the lowest below grade elevation of a building, and therefore are very susceptible to groundwater intrusion.

Concrete is widely used for foundation walls, the perimeter structural walls built on footings that support buildings within the soil below ground level in basement and sub-basement areas. The pit, appropriately named as it exists below the lowest floor slab level of a building, housing all equipment and supports, reaches closer or within the groundwater table than any other part of a building. Stress cracks occur when newly poured concrete hardens and water evaporates causing the concrete to shrink and crack. Cracks also occur from the settlement of the footings into the soil below; from temperature changes that cause expansion and contraction; and from the vibrations of passing traffic.

Water infiltration is a constant risk, especially when the ground is saturated after winter’s thaw or a heavy rain. Water enters most commonly from the interface from the bottom of a wall to the floor slab, where the footing is situated directly below; it can also come from cracks on the floor slab or cracks and cold joints on the foundation walls.

The CGI System – Concrete Gel Injection

Since 2004, a specially developed system to stop and prevent further underground water leakage has been successfully used by CGI Northeast in hundreds of residential and commercial buildings in the New York City metro area, including remediation of water intrusion to elevator pits.

The CGI system involves below ground injection waterproofing from the interior side of a building without excavating from the exterior. The system drills holes and injects a two component hydrophilic resin that chemically reacts to form a flexible water sealing gel through the process of polymerization.

The two liquid components combined are near the viscosity of water. When the CGI chemical reaction takes place, the gel doesn’t expand like urethane foam, it simply occupies the volume of the crack or cold joint full depth to the exterior side. The system doesn’t drill all the way to the exterior (only within a certain depth of the structure), which could compromise any previously installed waterproofing membrane and allow additional unwanted water to enter. No excavation is needed. It can be performed through brick and stone walls and structural vaults.

The CGI system has the following distinct benefits:

• The gel is highly elastic - flexible to vibrations/movements;

• It is less costly than methods requiring major overhauls such as excavation;

• It is easy to clean with water - no cleaning solvents required;

• It produces little to no odor;

• It will not promote growth of fungi, mold, or bacteria;

• It is environmentally safe and non-toxic, non-flammable, and non-hazardous;

• The gel, unlike grout, will not eventually break down in the presence of water; it can mix and coexist with water containing oil, salt and/or sewage; and

• It does not require drilling to the exterior side to form a curtain wall membrane.

A few of the locations that have utilized the CGI system to repair elevator pits are: Royal Charter Properties at New York Presbyterian Helmsley Tower (1320 York Ave.); Milan/Quatrone Property Management at 307 W. Broadway; First Service Real Estate Management, now Colliers International at 1201 Broadway; Magnetic Construction Management at 1466 Broadway; and Avalon Communities Management in Stamford. Buildings that have successfully eliminated leaks through the CGI system are NY Presbyterian Hospital/The Helmsley Medical Tower; London Terrace at 435 W. 23^rd St.; the GM Building at the Fifth Ave. Apple Store; The New Yorker Hotel; several NYU locations; The Ritz Carlton Hotel; The Time Warner Building at Columbus Circle; The BMW Building; Zankel Hall at Carnegie Hall and The Bank of America Building at Bryant Park.

George Doukas is the executive vice president of CGI Northeast Inc., Long Island City, N.Y.