The busy A948 Ellon to New Deer road in Auchnagatt is to close from Monday, August 21 for two weeks.
The road will be closed from the 30mph signs (north side) to the C112B to allow carriageway resurfacing works to be completed.
Motorists will be diverted along the B9030 Auchnagatt to Old Deer road past Auchnagatt School.
An Aberdeenshire Council spokesman said: "The diversion is lengthy due to the rural nature of the location and the requirement that a diversion must divert to roads that are the same class as the one that is closed.
"Heavy Goods Vehicles must be taken account of in any diversion and that is the case with this closure too.
"It is also worth noting there are a number of smaller roads locals could use that would cut the diversion length considerably although we try not to create 'rat runs' by publicising this fact.
"We often estimate closures in the 'worst case scenario' and roads may well open ahead of schedule."
In addition, the C143B Boyndlie Road from B9031 at Crossgate to U143B Wards of Boyndlie will be closed from the same date for three weeks.
The route will be closed between Pennan Road at Crossgate and the Wards of Boyndlie. Diversions will be signposted.
Aberdeenshire Council has apologies for any inconvenience caused while the works take place.
Details of all road closures and restrictions in Aberdeenshire are available on our website: http://online.aberdeenshire.gov.uk/apps/roadclosures/."