| Built in 1972, Skyline Tower is a
twenty-four story, concrete-framed apartment building located in St. Paul,
Minnesota. In April of 1999 French Engineering performed a Cladding
Condition Survey in order to provide an evaluation of the overall cladding
system at the high-rise complex. Our investigation specifically focused on
the current performance and anticipated service life of the cladding
assemblies consisting of retrofitted, polymer-based (PB) Exterior
Insulation and Finish System (EIFS) at Floors 2 through 24, and true
stucco spandrels and columns at Floors 1 and 2. Results of our survey and investigation revealed large areas of
patterned cracking within the EIFS lamina at window heads, equipment
penetrations, building notches, and along underlying insulation board joints. Expansion joints and reveals were
provided only at every fourth floor level, and were not completed at the
return of window opening recesses. Window sill flashings were installed
using a three piece construction without end dams, and relied heavily on
sealant at the metal laps and EIFS interface. The integrity of
sealants was severely compromised in most locations, including adhesive
failures, cohesive failures and embrittlement, as well as surface cracking
at stress points.
Following our investigation and recommendations for repair, the owner
of this complex determined that it would proceed with the cladding
renovation and that French Engineering would provide construction
documents, as well as full-time Quality Assurance Inspections. The
cladding renovation design included removing the existing EIFS cladding
assembly and installing a new, PB EIFS system over all areas
(approximately 130,000 S.F.), as well as incorporating stainless steel
through-wall flashings at every floor level, and a one-piece sill flashing
at all window locations.
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