Client: International Conservation Services

Location/Site: Duntroon House, Canberra ACT

Project: Courtyard conservation clean

Scope of Works: Let’s Clean was asked to provide a conservation clean of the stone pavers in courtyards 1, 2, and 3, and the conservatory courtyard at heritage-listed Duntroon House, which had been subject to lichen growth and staining from weather.

Method: Hot water (~ 90ºC) at low pressure (~ 600 psi) was used to clean the stone pavers in each courtyard, delivered via the BlueVac Captive Head Washing System with a floor tool attachment. Each clean was followed with an application of Boracol 100RH, a biocide commonly specified for heritage conservation works which inhibits biological growth.

Outcome: The cleaning of stone pavers in each courtyard was pleasing, and the natural colours are now visible and vibrant. Some areas remained somewhat dirty, likely the result of prolonged dirtying or the absence of sunlight. The application of biocide was performed after the stone cleaning and may, over time, assist in weakening blemishes resulting from biological growth. (Courtyard 3 pictured above, other courtyards pictured below.)

We recommended a 12-month review to determine if a follow-up clean and/or another biocide application is required.