The closure will allow a complete reconstruction of the old A38 carriageway to take place, providing a better road surface for drivers.
The work has been made possible by the opening of the new A38 bypass to traffic at the end of 2008, built by Interserve for £32M.
Traffic in the village of Dobwalls has reduced by around 90% since the new road opened in September, providing a safer and quieter environment for the village as a whole.
Work on the scheme began in November 2006 to reduce the long traffic queues through the village and improved journey times for all road users. Work is continuing on the A390 county road to St Austell which joins the bypass at the new roundabout to the west of the village and is due to be completed in March 2009.
A short diversion route will be clearly signed during the closure.
Eastbound traffic will be directed off the bypass at the new Looe Mills Interchange and westbound traffic will come off at the Dobwalls East junction.
Pedestrian and cycle access will be maintained throughout the work.