CALGreen – Deconstruction and Reuse of Existing Structures

CALGreen – Deconstruction and Reuse of Existing Structures

Huge amount of material goes into constructing a building. Some of these materials can last a long time, sometime even longer the life of the building itself. At the end of a building’s life these materials can be salvaged and reconfigured to be used elsewhere. Code also promotes using existing vacant structures instead of building new. This is a voluntary measure for Non-Residential buildings. Code language is as follows. 

CALGreen Code Section A5.105.1:

 If feasible, disassemble existing buildings instead of demolishing to allow reuse or

recycling of building materials.

CALGreen Code Section A5.105.1.1: Existing building structure. 

Maintain at least 75 percent of existing building structure (including structural floor and roof decking) and envelope (exterior skin and framing) based on surface area.


1. Window assemblies and nonstructural roofing material.

2. Hazardous materials that are remediated as a part of the project.

3. A project with an addition of more than two times the square footage of the existing building.

CALGreen Code Section A5.105.1.2: Existing nonstructural elements. 

Reuse existing interior nonstructural elements (interior walls, doors, floor coverings and ceiling systems) in at least 50 percent of the area of the completed building (including additions).

Exception: A project with an addition of more than two times the square footage of the existing building.

CALGreen Code Section A5.105.1.3: Salvage. 

Salvage additional items in good condition such as light fixtures, plumbing fixtures and doors as follows. Document the weight or number of the items salvaged.

1. Salvage for reuse on the project items that conform to other provisions of Title 24 in an on-site storage area.

2. Nonconforming items may be salvaged in dedicated collection bins for exempt projects or other uses.


The intent of these provisions is to salvage and recycle as much existing material as possible during deconstruction processes and to minimize potential landfill deposits. The use of recovered versus new building materials cuts down on the continual consumption of natural resources, energy and water-intensive industrial processes, and greenhouse gas emissions due to the requirements of transporting manufactured materials.

There is also an economic factor to be considered. There is an established value to reusing existing structures and materials.

Always check with the local jurisdiction regarding existing ordinances for these provisions.

Compliance Method:

Existing building structure (A5.105.1.1). Document using calculations to establish that the 75-percent minimum requirement for existing building structural components remains after improvement; show on a demolition, site or building plan.

Existing nonstructural elements (A5.105.1.2). Document using calculations to establish that at least 50 percent of the area of the completed building employs reuse of existing interior nonstructural elements; indicate on the plans.

Salvage (A5.105.1.3). Document using calculations to establish the salvage weight or number of items salvaged.


Plan intake: The plan reviewer should review the plans and calculations that show the required percentages of reused existing building elements.

On-site enforcement: The inspector should review the permit set of plans and confirm that the required percentages of elements have been integrated, reused and salvaged as shown.

Suggestion: Promote the concept of recovering and reusing existing building elements to design professionals. If the approach is incorporated from project conception, and the disassembling process, corresponding cost savings and other potential innovative discoveries can result. 

(Excerpted from ‘Guide to the 2019 California Green Building Standards Code Nonresidential’ – Chapter 5)

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