An established and recognized agency regularly engaged in conducting tests of furnishing inspection services when such agency has been approved by the building official is called?

The term "approved agency" refers specifically to an organization that has met the necessary criteria set by building officials to conduct tests and provide inspection services. This designation signifies that the agency is recognized for its competence and reliability in performing the necessary evaluations as per the standards of the local building codes.

Being "approved" implies that the agency has undergone a vetting process and has received the endorsement of the building official. This approval is crucial for ensuring that inspections and tests are carried out in accordance with the regulations, providing assurance of safety and compliance to both builders and occupants.

In contrast, while the terms "certified agency," "accredited entity," and "registered organization" might sound similar, they carry different meanings and implications in the context of regulatory compliance and inspection services. Certification often relates to specific qualifications or credentials that an organization or individual holds, while accreditation typically involves a higher level of recognition by a third-party organization. Both certification and accreditation do not inherently guarantee approval from local building officials, which is the distinguishing factor for the designation of "approved agency."