Every July, the house is closed to the public while a team of volunteers carries out the annual spring clean.
All the silverware is polished, all the crockery, fine chinaware and linen is washed and all the furniture is polished.
Woodridge House was built between 1883 and 1885 for the pioneer and entrepreneur Charles Harper and his wife Fanny.
It is a rose-coloured brick, two-storey mansion set high on the banks of the Swan River, where the couple raised 10 children.
Three of their sons joined the 10th light horse regiment in World War I.
Woodbridge is open to the public from Thursday to Sunday and on public holidays from 1 to 4pm.
The National Trust also has an extensive education program based at Woodbridge with links to the national curriculum.
Many schools visit each year with programs Guildford to Gallipoli and Meet the Harpers being among the most popular with students.
Group tours with National Trust guides can be booked by calling 9274 2432.