The local heritage-listed building was built to supplement the Laggan mill and opened in 1871. It has also housed a museum since 1989.

Custodian Susanne Hutton is working with builder Colin Jewell to restore the old building.

The scaffolding presently surrounding the old mill is for the roof work.

Within the month, nine blackbutt timber beams weighing 1.8 tonne will be craned into position on top of the stone walls to support the roof.

"Three 7.9 metre beams are to run north-south, and six other beams, about five metres, will join in the middle and run east-west," Ms Hutton said.

"We are retaining the old beams. The old beams will be cradled to the new beams with steel plates and bolts."

The roof sheeting was in worse condition than anticipated and can't be reused. Ms Hutton is devising a new plan to replace the sheeting.

Roof works are expected to continue for about a month. It is estimated the exterior completion will be in about three months. However, there could be delays due to Christmas and New Year, Ms Hutton said.

Ms Hutton bought the mill in 2017 and the Upper Lachlan Shire Council approved the renovation and preservation of the building.

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