How is Clementine able to purchase her home after it goes up for sale in the novel, The Wise Women?

While Clementine, her mother, and her sister are spying on people attending the open house intended to bring in a buyer for the house, it is mentioned that the new owners will have issues with the roots of the London plane tree if they intend to dig a basement or increase the foundation. Clementine is able to buy the house after it is determined that no work can be done to change the foundation of the house because the roots of the tree have grown into it.