Substitute Materials

Historic materials should be used whenever possible. Substitute materials — those products used to imitate historic materials — should be used only after all other options for repair and replacement in kind have been ruled out. Substitute materials are normally used only when the historic materials or craftsmanship are no longer available, when the original or existing materials are of a poor quality or are causing damage to adjacent materials, or when there are specific regulations that preclude the use of historic materials. Use of these materials should be limited, since replacement of historic materials on a large scale may jeopardize the integrity of a historic place.

Every means of repairing deteriorating historic materials or replacing them with identical materials should be examined before turning to substitute materials. Because there are so many unknowns regarding the long-term performance of substitute materials, their use should not be considered without a thorough investigation into the proposed materials, the manufacturer , the installer, the availability of specifications and the use of that material in a similar situation in a similar environment. The importance of matching the appearance and physical properties of historic materials and, thus, of finding a successful long-term solution cannot be overstated.

The long-term performance of many substitute materials is uncertain. This is why historic materials should be used wherever possible. Instead of repairing and repainting the wood elements of this character-defining balcony (original balcony above, altered balcony below), the existing wood structure was covered in metal and fiberglass cladding. The original colours that matched the remaining wood windows and details such as a drip moulding were lost. Materials that are considered “low-maintenance” are often used as new substitutes, although they may be less durable in the longer term.

Under certain circumstances, substitute materials may be appropriate. As part of a Rehabilitation project, new finials were designed based on remains of originals. The originals were fabricated of wafer thin galvanized metal soldered together. The substitute material used in the new design was plate aluminum.