Problem
Katy and her family lived in a two-story house in Lindfield, on Sydney's north shore. Following the extensive and torrential rains earlier this year, she approached Stuart, a roofing contractor, to inspect her roof and replace any damaged roof tiles that he finds. Additionally, she arranged with him to install a large satellite dish on her roof to improve her television reception. Stuart arrived at the pre-arranged time, and brought with him all of the necessary parts and tools that he might need for the job. Considering the size of the satellite dish involved, he also brought his apprentice, Andrew, for assistance. Andrew was only at the beginning of his apprenticeship, and had not yet had the opportunity to learn any real skills in his trade, but would be helpful in maneouvering the large dish into place. Recognising that this was a large house on a relatively small block of land, Stuart, as a courtesy, elected to notify the neighbours on both sides of Katy's property of the work that was taking place that day, and the possible, although unlikely, risk of a tool or debris falling from Katy's roof.
1) Sarah, the neighbour on the left side of Katy, was at home and thanked Stuart for letting her know about the work being done. She told him that she would move her pot plants and garden furniture to the opposite side of her yard as a precaution.
2) No-one was home in the house on the right side. Katy told Stuart that both Allan and Joanne who lived in the house, left early each morning to their workplaces in the city. Stuart made a mental note to be especially careful with any work on that side of the roof. About halfway through the job, the wet weather returned, and light showers started to fall, making the roof area wet. In order to complete the work all on the one day, Stuart opted to start work on the satellite dish by himself, leaving Andrew to finish clearing the broken roof tiles that had been removed and replaced from Katy's roof. As he was carrying some of the broken tiles across the roof towards the rubbish skip, Andrew slipped slightly on a wet area of the roof. Whilst the harness he was wearing saved him from falling the six metres to the ground, he lost his grip on the tiles in his hands. The tiles dropped by Andrew fell over the dividing fence onto Allan and Joanne's property. Unfortunately, the tiles smashed through the glass roof of the greenhouse in which Allan stored his collection of miniature bonzai trees, causing extensive damage to the valuable collection. The sound of breaking glass startled Stuart on the other side of Katy's roof, and he loosened his grip on the large satellite dish when he turned to investigate. A gust of wind, associated with the rain that was now falling more heavily, pulled the satellite dish from his grasp and over the side of the roof. It too cleared the dividing fence and crashed into a number of Sarah's potted fruit trees, destroying both the trees and their pots with its weight. It appears that Sarah had forgotten to move her pot plants and furniture out of harms way, as she had promised.
Advise Stuart on his liability in negligence for the damage caused by himself and Andrew.
Support your argument with relevant statute or case law. The IRAC method MUST be used.