Ontario, CA Fence Regulations: Neighbor Fence Rules (2026)

California Civil Code Section 841, known as the Good Neighbor Fence Act, creates a statewide presumption that adjoining owners share equally the reasonable costs to construct, maintain, and replace a fence on the common boundary line. Before building or replacing a shared fence, an owner must give the neighbor at least 30 days written notice that includes the nature of the problem, the proposed solution, the estimated cost, the proposed cost sharing, and the proposed timeline. A neighbor who believes the cost or design is unreasonable can rebut the equal-share presumption based on their financial situation, the benefit to each parcel, the aesthetic impact, or other relevant factors. Ontario city staff do not mediate private fence disputes and generally refer residents to small-claims court for cost disputes. Surveys to confirm the actual property line are often advisable before construction. Encroaching fences built on a neighbor's land can create prescriptive easements over time and should be corrected promptly.