Urgent repairs to New Bridge in Chudleigh Knighton are due to get underway next week.
The Grade II listed structure at Clay Lane, which dates from 1845, will be completely closed from Monday 10 August to Friday 28 August.
The stone apron that protects the foundations of the granite bridge was damaged during Storm Dennis earlier this year, and a routine inspection has found that it has further deteriorated.
Repairs need to be carried out while levels of the River Teign are low, so the work is weather dependant.
The closure of the bridge is essential to allow the work to be carried out safely and to provide access for machinery and materials. The bridge will be closed to cyclists and pedestrians as well as all traffic.
A signed diversion will be in place via the A38 (between Drumbridges and Chudleigh) and the B3193 Clay Pits Road, although local traffic may find alternative routes