What lies beneath: conservation works

Two conservation projects demonstrate the complex factors to consider when working with heritage buildings.

Under the paving stones at Rouse Hill House & Farm

When Edwin and Hannah Rouse took up residence at Rouse Hill Estate in 1855 they made some modest improvements, such as adding the verandah to the main house and constructing the picturesque little bathhouse in the garden. Thought to have been designed and built in 1858 by Scottish-born Parramatta builder and architect James Houison (1800–1876), the bathhouse originally featured fine arched timber trellises on the verandahs and porches on each side; only one arch and panel remain.

While the bathhouse contains the prosaic requirements of bath, basin, chip heater and two toilets, it was also ornamental. The delicate treillage supported climbing plants like black-eyed Susan and Japanese honeysuckle, and also fulfilled another, more ‘polite’ function: to provide some privacy for those entering or leaving the bathroom and lavatory.

Still featuring its original Morewood & Rogers tinned roofing tiles, the little building has seen many repairs and patches. Gerald Terry, one of the last members of the Rouse and Terry families to live at Rouse Hill House, wired new supports onto the trellis when the bottoms rotted away, and in the 1960s replaced the porch over the bathroom door with a robust sheet-metal awning. More recently, SLM staff noticed evidence of structural movement, as well as ongoing deterioration of the remaining treillage, stonework plinth, paving and brickwork.

We asked Simon Wiltshier, a structural engineer familiar with historic building conservation, to investigate the situation. To our relief, he found that the cracking wasn’t progressing. However, tree roots were significantly affecting the surrounding paving and dwarf walls, so we decided to install root barriers and improve below-ground drainage around the building.

Our conservation policy at Rouse Hill is to stabilise and preserve rather than restore or renew, so the repair work involved carefully dismantling and lifting much of the stonework to reveal the footings and foundation. We made a detailed set of measured drawings and took photographs to record the state of the building before works commenced. Our gardeners relocated plants and pots from the surrounding garden beds, ready to go back when the work was complete.

Stonemason Ken Ellis and his assistants carefully lifted the paving, numbering each stone and setting them aside. The trellises were propped up so the plinth stones could be lifted. Ted Higginbotham, an archaeologist with long experience on this site, monitored the works and investigated some brick channels found beneath the paving. The channels lead to the bathhouse from the direction of the cistern under the main house, and may have been remnants of an early flushing system, possibly belonging to a previous structure or privy.

When the trenches were dug for the root barriers, we found a web of large tree roots encircling the bathhouse. These roots come from a large Moreton Bay fig, originally planted by Hannah Rouse in the 1860s or 70s, some 25 metres away near the carriage circle. An arborist advised us how to safely cut the roots without injuring the tree, and these were cut back under the paving and the cuttings removed so that they won’t cause the paving to subside when they decay.

The paving has now been relaid, the trellis stabilised, bulbs and pelargoniums replanted, and the brickwork joints repointed with lime mortar, giving the little bathhouse a new lease of life.

Investigating damp at Vaucluse House

Conservation of old buildings requires clever detective work to investigate and uncover the cause of a problem before trying to fix it. Traditional materials and building practices almost always turn out to be the best solution.

The rear of Vaucluse House has suffered from damp for many years, a problem familiar to many an owner of an old house. By 2016, the plasters and surface finishes in the covered colonnade had deteriorated and the time had come to address the problem. Although there’s evidence of rising damp around the entire kitchen wing, Curator Joanna Nicholas and I noticed that the biggest contributor to the problem was rain flowing off the porch roof over the worn paving and collecting in pools in the colonnade. However, we didn’t wish to replace the worn paving which was so evocative of the many years of human footsteps.

The porch was relatively recent, so we decided to replace it, but with a slightly larger one that would shed water better. A new gutter and downpipe now drain into a new drainage line beneath sandstone paving that had been recently laid. With the causes of the problem addressed, we then removed damaged plaster from the bottom of the wall. Salts in the masonry wall behind were removed by poulticing (applying a dry paste that draws out contaminants), and the damaged plaster was renewed with a traditional three-coat lime plaster. All of the colonnade’s walls were then finished with a lime-wash mix including tallow (animal fat) and ochres to match the shade of adjacent surfaces. These low-tech, hand-mixed products should now do the job for many years to come.

‘Conserve as found’ at Rouse Hill House & Farm

Rather than replacing old material with new, our approach at Rouse Hill House & Farm is to support as much of the built fabric as possible, to maintain the condition of the property as it was when it came to SLM. We also aim to minimise the impact of any works on the building.