1666: How the Great Fire of London Created Modern Building Regs
Modern UK building regulations—specifically regarding party walls and fire safety—were born directly from the ashes of the Great Fire of London in 1666.
When property developers curse the complexity of modern Building Regulations and Party Wall agreements, they are dealing with legislation whose roots trace directly back to September 1666. Before the Great Fire, London was a medieval warren of timber-framed houses, jettied out so far that neighbours on opposite sides of the street could shake hands from their upper windows.
The London Building Act of 1667
Following the devastation of the fire, Parliament passed the Rebuilding of London Act 1667. This was effectively the UK's first comprehensive building code. It mandated that all new houses must be built of brick or stone—banning timber frames entirely in the city. It standardised street widths to act as firebreaks and, crucially, it regulated the thickness of party walls separating adjoining properties to prevent fire spreading horizontally.
This legislation fundamentally changed the architectural face of London, birthing the flat-fronted, brick-built Georgian terrace that still defines much of the capital today. The principles of the 1667 Act laid the foundation for the Party Wall etc. Act 1996, which developers still use today when altering shared boundaries.