Lawrence died in 1752, and his will stipulated that his widow should own a life estate in Mount Vernon, the remainder interest falling to his half-brother George; George Washington was already living at Mount Vernon and probably managing the plantation.
Lawrence's widow, Anne Fairfax, remarried into the Lee family and moved out.
Following the death of Anne and Lawrence's only surviving child in 1754, George, as executor of his brother's estate leased his sister-in-law's estate.
Upon the death of Anne Fairfax in 1761, he succeeded to the remainder interest and became sole owner of the property.

In 1758, Washington began the first of two major additions and improvements by raising the house to two-and-a-half stories.
The second expansion was begun during the 1770s, shortly before the outbreak of the Revolutionary War.
Washington had rooms added to the north and south ends, unifying the whole with the addition of the cupola and two-story piazza overlooking the Potomac River.
The final expansion increased the mansion to 21 rooms and an area of 11,028 square feet.
The great majority of the work was performed by African American slaves and artisans.
Lawrence died in 1752, and his will stipulated that his widow should own a life estate in Mount Vernon, the remainder interest falling to his half-brother George; George Washington was already living at Mount Vernon and probably managing the plantation. Lawrence's widow, Anne Fairfax, remarried into the Lee family and moved out. Following the death of Anne and Lawrence's only surviving child in 1754, George, as executor of his brother's estate leased his sister-in-law's estate. Upon the death of Anne Fairfax in 1761, he succeeded to the remainder interest and became sole owner of the property.
In 1758, Washington began the first of two major additions and improvements by raising the house to two-and-a-half stories. The second expansion was begun during the 1770s, shortly before the outbreak of the Revolutionary War. Washington had rooms added to the north and south ends, unifying the whole with the addition of the cupola and two-story piazza overlooking the Potomac River. The final expansion increased the mansion to 21 rooms and an area of 11,028 square feet. The great majority of the work was performed by African American slaves and artisans.
Mount Vernon