Masonry Magazine February 1985 Page. 33
FACADE REHABILITATION:
SOLVING PROBLEMS THROUGH RE-ANCHORING
Reanchoring facades to existing buildings can be a major problem for specifiers. Here's some advice on how to approach a facade rehab project.
By S. H. Getz
Weather and other corrosive influences can take a toll on the original anchoring systems of primary building structures. To combat this problem, ITT Phillips Drill Division has devised ways to resupport the facades of projects in several states. Each project required the reanchoring of a facade to concrete or masonry sub- structure. In one instance, the loss of support resulted in a marble panel falling several floors to a sub-roof area. No one was injured, but the owners were concerned for the safety of occupants and pedestrians.
Factors contributing to the eventual loss or weakening of anchoring systems included numerous freeze and thaw systems, the expansion and contraction behaviors of certain materials, and the omission of wall ties or installation of ties other than specified. In addition, corrosion preven- tative materials may have been limited at the time of con- struction or possibly the proper material or product spec- ification was not made.
Certain repair considerations and techniques are vital to the designer involved in rehabilitation projects. Typically, the designer has three methods of repair he or she can consider:
* Remove and replace the total facade.
* Remove and reanchor partial or selective facade sec- tions.
* Reanchor facade with mechanical anchoring sys- tems.
Complete removal of a facade and subsequent replace- ment must be considered both in terms of practicality and expense. The removal of several stories of marble or brick veneer raises questions of safety and cost effectiveness. Costs must be measured against projected building utili- zation.
Partial removal of sections of the brick veneer requires installing a new wall tie or anchoring system and replacing the brick sections. Mechanical anchoring is both the most practical and the most cost effective of the three methods and is considered the preferred repair technique. Instal- lation procedures may be unique for various facade repairs but do not require the removal of wall segments or panels.
Resupport Problems
The facade "resupport" problems that specifiers posed
S. H. Gettz is Engineer Manager, Anchor Systems ITT Phillips Drill Division. He works with architects and contractors to help solve their facade rehabilitation problems. This article is re- printed with permission of The Construction Specifications In- stitute from The Construction Specifier, June, 1984.
MODIFIED "WEDGE" ANCHOR Figure 1
to the anchoring specialists at ITT Phillips Drill resulted in the design and manufacture of three separate mechan- ical type anchors.
The marble panels on a 14-story concrete office build- ing in Chicago, Illinois, required a corrosion-resistant an- chor for resupport that could be installed with ease and would provide an aesthetic finish. Avoiding stress on the marble panels during actual installation and attaining structural stability with work loads of 600 to 700 pounds were other considerations.
The system developed combined an austenitic stain- less steel "wedge" type anchor with internal threads, nec- essary for the expansion into concrete and final cosmetic appearance on the marble panel; a 303 stainless steel sleeve, which absorbs compression forces of expansion and pre- load; and an 18-8 stainless steel button head cap screw and washer for a cosmetically appealing finish (see Figure 1).
The facade resupport system structurally provided ul- timate loads at about 7,000 pounds when applied at 90 degrees to the anchors' centerline and five inches from the building's concrete surface. The system allowed a "dowel" support for the panel in the event of a failure in its primary support system. The existing primary support system was a ledger and adhesive with copper tie backs.
The newly designed facade-resupport anchor sup- ported the panel and gave it room to "breathe" without adding stress while providing a mechanism so the facade would stop "falling away" from the building.