Third-party agencies (PDF) are approved by the Department of Housing and Community Development's (HCD's) Manufactured Housing Program to perform as a Design Approval Agency (DAA) and/or a Quality Assurance Agency (QAA), enforcing design and construction approval of commercial modulars, special purpose commercial modulars, and multifamily manufactured homes designated for sale in California.

Third-party agencies are businesses, certified by HCD, to provide these services acting on behalf of HCD.