13th St Sanctuary

The Project

Ehlert Bryan was tasked with the challenge of converting an existing, historic church building into a three-story residential apartment building, all while maintaining the historic façade and roof structure in place throughout construction and incorporating them as part of the final structure. The existing timber roof structure was partially cut and re-purposed to support the new roof expansion. The load-bearing exterior masonry walls were cut throughout and re-stitched together to allow for the architectural modernization.

The Challenge

Three major challenges were posed with the proposed work:

1. Zoning required that half of the existing roof remain undisturbed throughout the entire construction process. The existing, large wood-framed trusses were required to remain in place (and hold the roof) while their ends, interior web members, and supports were removed.
2. The architectural design required that a series of large, vertical window slots were cut through the height of the building around the perimeter, which did not align with the existing window openings. This demolition, along with the removal of the roof perimeter and the mezzanine level, made the task of preserving the structural integrity of the heavy masonry walls challenging.
3. Given the coexistence of complex temporary shoring and new construction, the construction feasibility and sequence would require careful, thoughtful consideration.

The Solution

At the roof, custom steel brackets, steel tension rods, and wood beams were used to restore the structural integrity of the modified existing roof trusses by converting them into a tied rafter system while they remained in place. Beams were designed to transfer these modified trusses to supports within the new architectural layout. A detailed sequence was established to maintain structural integrity of the trusses throughout demolition, during construction, and in the final design.

At the exterior, where full-height slots were cut through the heavy masonry walls, custom steel frames were provided around the openings to reinforce the wall and support new and partially removed existing lintels. This frame also supported outriggers to create architectural “fin” elements around these openings. At each floor, a continuous wood beam was bolted to the wall to tie each wall segment together and to the floor diaphragm.

An elaborate temporary shoring structure and sequence had to be developed to support the trusses and exterior walls during construction. Ehlert Bryan provided a creative conceptual design to allow the contractor and its specialty engineer to shore, demo, and build the new structure around these elements without disturbing the portions to remain.