Hempstead Road, Uckfield, is to be closed from Monday for five days while scaffolding is in place at the side of 188 High Street.
East Sussex County Council said the closure is at the request of Oldfield Smith & Co to enable their contractor to work safely.
The diversion will affect the one-way section of the road between Hempstead Rise and High Street, with access to the Cinque Ports Club maintained.
A diversion will be in place via Hempstead Rise, Grange Road and High Street.
The council said a further closure would be required from September 16 to 20 to remove the scaffolding once repairs on the property have been completed.
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