Historic Preservation and Sustainability

Preserving and maintaining historic buildings is one of San Dimas’ best opportunities for sustainability.  Sustainability is defined as “the practice of meetings the needs of the present without compromising the ability of future generations to meet their own needs.”  Preserving historic buildings ensures that the environmental resources that have already been expended continue to be used and protects those who have not been used.  Reusing sound older buildings makes much better sense than abandoning or demolishing them.  Preserving and using San Dimas’ historic resources is recycling on a community-wide scale.

Historic Survey

The City of San Dimas has a rich history that goes back into the nineteenth century. To document the historical significance of structures in San Dimas, the City surveyed all pre-1940 buildings in 1991. Over 300 structures are listed as locally significant, state level significance or potential national register.
Explanation of Survey List Significance:
  • LS — Locally Significant. Structures that are important to the local historical framework. These structures may be good examples of architecture or locations where critical local events occurred.
  • NS — Nationally Significant. Structures that are eligible for National Register status.
  • CS — Contribution Structure. A structure that significantly contributes to the historic fabric of a neighborhood.
  • USDHD — Upper San Dimas Avenue Historic District. A proposed district within the city that is eligible for National Register status because of its overall character.
  • LSDHD — Lower San Dimas Avenue Historic District. A proposed area in the town that is eligible for National Register status because of its whole style.
The column National Status refers to the code for the National Trust for Historic Preservation guidelines for historic structure status.

Town Core Design Standards

Downtown San Dimas is a prime example of the traditional American town center, dominated by a short but prominent main street. Surrounding the historic downtown is a “Town Core” area comprised of numerous historic homes, businesses, and churches. As a follow-up to the 1991 landmark survey, the City hired a local architect to prepare design guidelines to help building owner’s to preserve and rehabilitate these historic buildings. The Town Core Design Guidelines were adopted by City Council in 1993.

Preservation Tax Incentives for Historic Buildings

Tax advantages are available at the local, state and federal levels for owners of historic properties. Any structure identified as a “Historic Resource” by our 1991 Historic Resources Survey adopted by the City Council is eligible for local tax incentives. The Mills Act is a state law that enables a homeowner of a structure, listed as historically significant by the City of San Dimas, to agree (historical property contract) with the City to preserve, maintain and possibly rehabilitate the home or structure. The benefit to the homeowner is a substantial reduction in property taxes for the post Proposition 13 qualified historic properties.

The money saved from the reduced property tax will be available for the homeowner to use to maintain and restore the structure. In San Dimas, the Mills Act requires that the homeowner spend their tax savings on preserving and restoring the historic structure. Homeowners are encouraged to “go green” in conjunction with their efforts to repair or rehab older homes. Under selected circumstances, expenses associated with the rehabilitation of historic properties may also be taken as a tax deduction.

Mills Act Eligibility Criteria 

Must be a privately owned property which is not exempt from property taxation.
Must be identified as a “Historic Resource” by the City of San Dimas 1991 Historic Resources Survey adopted by the City Council and must not have been altered since the 1991 survey in a manner that would change its historical significance.

“Buildings…must include all of their basic structural elements” consistent with the Guidelines For The Assessment of Enforceably Restricted Historic Property adopted by the State Board of Equalization on May 25, 2005. The Guidelines further state, based upon Section IV of National Register Bulletin #15, that: “Parts of buildings, such as interiors, facades, or wings, are not eligible. A newly constructed building is not a historic resource, and thus, is not a qualified historic property within the meaning of Government Code section 50280.1.

For example, a newly constructed detached garage (assuming it is not a reconstruction of an old garage) undoubtedly would not be eligible because it has no significance in American history or architecture, nor does it meet any of the other requisite criteria.

Standards for Historic Preservation

The City of San Dimas follows the rules known as the “Secretary of Interior Standards for Rehabilitation,” listed below, that were developed by the U.S. Department of Interior. “Rehabilitation” is defined as “the process of returning a property to a state of utility, through repair or alteration, which makes possible an efficient contemporary use while preserving those portions and features of the property which are significant to its historical, architectural, and cultural values.”

The 10 Standards pertain to historic buildings of all materials, construction types, sizes, and occupancy and encompass the exterior and the interior, related landscape features and the building’s site and environment as well as attached, adjacent, or related new construction. The following Standards are to be applied to specific rehabilitation projects in a reasonable manner, taking into consideration economic and technical feasibility:

  • A property shall be used for its historic purpose or be placed in a new use that requires minimal change to the defining characteristics of the building and its site and environment.
  • The historic character of a property shall be retained and preserved. The removal of historical materials or alteration of features and spaces that characterize a property shall be avoided.
  • Each property shall be recognized as a physical record of its time, place, and use. Changes that create a false sense of historical development, such as adding conjectural features or architectural elements from other buildings, shall not be undertaken.
  • Most properties change over time; those changes that have acquired historic significance in their own right shall be retained and preserved.
  • Distinctive features, finishes, and construction techniques or examples of craftsmanship that characterize a property shall be maintained.
  • Deteriorated historic features shall be repaired rather than replaced. Where the severity of deterioration requires replacement of a distinctive feature, the new feature shall match the old in design, color, texture, and other visual qualities and, where possible, materials. Replacement of missing features shall be substantiated by documentary, physical, or pictorial evidence.
  • Chemical or physical treatments, such as sandblasting, that cause damage to historical materials shall not be used. The surface cleaning of structures, if appropriate, shall be undertaken using the gentlest means possible.
  • Significant archeological resources affected by a project shall be protected and preserved. If such resources must be disturbed, mitigation measures shall be undertaken.
  • New additions, exterior alterations, or related new construction shall not destroy historic materials that characterize the property. The new work shall be differentiated from the old and shall be compatible with the massing, size, scale, and architectural features to protect the historical integrity of the property and its environment.
  • New additions and adjacent or related new construction shall be undertaken in such a manner that if removed in the future, the essential form and integrity of the historic property and its environment would be unimpaired. 
Building Preservation Resources

Some technical guides have been developed by the Secretary of Interior (The National Park Service) to educate the public about proper approaches to preserving, rehabilitating and restoring historic buildings. These in-depth Preservation Briefs cover a wide range of nearly four dozen topics including:
  • Exterior building additions
  • Cleaning methods for building exteriors
  • Siding treatments for historical wood frame buildings
  • Wooden window maintenance
  • Exterior paint problems
  • Historical storefront rehabilitation
  • Masonry maintenance practices
  • Use of substitute materials
Preservation Briefs are available online or can be ordered directly from the National Park Service