By their very nature, adaptive reuse projects challenge architects and specifiers, who typically cannot know all the work requirements and building conditions up front. In many cases, the design team learns as the demolition and adaptation work progresses. This brings an improvisational aspect to the design process, according to architects experienced in adaptive reuse. Additionally, some ‘grandfathering’ of existing conditions may be allowed.
“Under limited circumstances, a building alteration can be made to comply with the laws under which the building was originally built,” according to IEBC, “as long as there has been no substantial structural damage and there will be limited structural alteration.”
Further complicating the picture, some building repairs can use materials and methods like those of the original construction, while other repairs must comply with requirements for new buildings. IEBC describes three levels of alterations to existing buildings per the work area compliance method:
- Level 1, covering only replacement of building components with new materials;
- Level 2, including space reconfiguration; and
- Level 3, referring to extensive space reconfiguration exceeding 50 percent of the building area.
There are numerous typical scopes of work of which one should be aware.
Addressing the structural challenges of existing buildings can range from straightforward to extensive and invasive. Adaptive reuse projects may include requirements for seismic and wind retrofits to meet modern standards, which may be complicated to achieve in historic buildings.
“While many jurisdictions have adopted prescriptive standards, primarily for certain building types such as unreinforced masonry loadbearing walls, more sophisticated, performance-based evaluation methods allowed by some codes offer more flexibility,” says the National Park Service (NPS).
Mechanical, electrical, and plumbing systems
Designing improvements for existing and new mechanical, electrical, and plumbing (MEP) systems are challenging due to “many unknowns. Are there looming issues in the ceiling or behind a wall that cannot be accessed during our design survey?” asks Dewberry engineer Nicholas Saponara, PE.
Saponara adds the design basis should “determine building engineering tolerances and establish what is needed to maintain a minimum function of the building.”
Energy-efficiency codes, including mandates or incentives for conservation measures, also impact adaptive reuse. For example, the New York City Department of City Planning’s (DCP’s) Zone Green initiative allows for adding external thermal insulation to building walls without incurring floor-area penalties. Such incentives can increase flexibility for adding sun-control devices and rooftop additions such as solar hot water and green roofs.
Just as important as operational efficiency, experts contend, are the savings in embodied energy represented by adaptive reuse projects. Conversion of building use is an energy-saving methodology and one of its benefits is embodied energy and cost reductions provided by adapting and recycling the structure rather than building new.
Accessibility and supplemental accessibility
In any conversion of use, the main consideration for architects is applying current codes and zoning, including local accessibility rules and the 2010 Americans with Disabilities Act (ADA). In general, supplemental accessibility is widely mandated except in relatively rare cases due to compelling public interest. NPS describes “the need to balance accessibility and historic preservation,” and recommends a three-step approach for implementing accessibility modifications that protect the integrity of a property’s “character-defining features.”
These steps are:
- to review the historical significance of the property and identify its character-defining features;
- to analyze the existing levels of accessibility versus those required; and
- develop and compare viable accessibility options within a preservation context.
For nonhistoric buildings, ADA rules generally strictly apply. Additionally, IEBC requires alterations made to the areas of primary function must comply with current code and have accessible routes that are also code compliant. There may be exceptions, however, including the ‘20 percent rule,’ which says that the costs of providing the accessible route are not required to exceed 20 percent of the costs of the alterations affecting the area of primary function.