Tennessee Code Title 13. Public Planning and Housing § 13-21-205

(a) The legislative body shall not institute eminent domain proceedings pursuant to this part unless the commission has certified that the property is blighted or deteriorated. A property which has been referred to the commission by an agency of the municipality as blighted or deteriorated may only be certified to the legislative body as blighted or deteriorated after the commission has determined that:

(b) The findings required by subsection (a) shall be in writing and included in the report to the legislative body.

(c) The commission shall notify the owner of the property or a designated agent that a determination of blight or deterioration has been made and that failure to eliminate the conditions causing the blight shall render the property subject to condemnation by the municipality under this part. Notice shall be mailed to the owner or designated agent by certified mail, return receipt requested. However, if the address of the owner or designated agent is unknown and cannot be ascertained by the commission in the exercise of reasonable diligence, copies of the notice shall be posted in a conspicuous place on the property affected. The written notice sent to the owner or the owner's agent shall describe the conditions that render the property blighted and deteriorated, and shall demand abatement of the conditions within ninety (90) days of the receipt of such notice.

(d) An extension of the ninety-day time period may be granted by the commission if the owner or designated agent demonstrates that such period is insufficient to correct the conditions cited in the notice.