Project Category: Waterproofing

Waterproof expansion joints are essential in plaza decks. 401 N. Michigan, known to many as the Equitable Building, sits at heart of Chicago’s rich architectural offerings. It is literally bounded by vaunted landmarks–Tribune Tower, U of Chicago’s Booth School of Business, NBC Tower, and Apple’s latest signature riverfront store. The Wrigley Building, Trump Tower and others are reflected in 401’s glass façade from across the street.

Like much of the Magnificent Mile, 401 N. Michigan is surrounded by elevated plaza decks. And, like most of the rest of Chicago’s split-slab plaza decks it has been plagued by leaks–particularly through the myriad expansion joints that dissect these vast elevated spaces.

Like the Wrigley Building across the street, 401 N. Michigan was looking for a permanent, waterproof expansion joint solution. And like Wrigley, they found it in one of EMSEAL’s stable of FP (For Plaza) Systems, Migutan FP.

Plaza decks provide outdoor spaces for the enjoyment of tenants, patrons and the public. But functionally they are roofs, usually over occupied space. If they leak, that space is unusable–a terrible revenue loss to the property owner and a major pain to tenants when gutters and other water management methods are necessary handle the leaks.

Like all of EMSEAL’s FP (For Plaza) Systems, Migutan-FP installs on the structural slab of a split-slab design and straddles the expansion joint. It’s integral side flashing sheets tie into the plaza deck’s buried waterproofing membrane. This tie-in is static and permanent. It is not subject to the tensile stresses of “buried band-aid” seals that are stretched and stressed as the expansion joint opens and closes.

Watertight integration with the membrane is assured and checked with water tests prior to installing the wear-course.

The wear-course installs up to the Migutan FP rails. This ensures movement in the wear-course is bound by the expansion joint and the wear-course materials don’t buckle. 401 N. Michigan features a variety of wear-course materials like natural stone pavers, cast pavers, and concrete.

Brushed, colorized concrete makes up the wear-course on the Booth School of Business side of the plaza.

Watertightness through changes in plane and direction is a hallmark of EMSEAL’s. A factory-fabricated tee (and there are a bunch of them on this job) takes the labor and risk of getting it wrong off the installer and ensures continuity of seal.

The web of expansion joints that traverse Chicago’s elevated city present numerous unique intersections. Presale quality assurance and cooperation between installer and EMSEAL ensures that custom factory-fabricated transitions are possible and practical in all conditions.

Work on this project has been done in phases over three years. The Migutan FP can be left in place and connected to at a later date.

At the end of the day, the owner of 401 N. Michigan will enjoy (perhaps for the first time ever) leak-free, useable, rentable, tenantable space beneath its impressive plaza decks.

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