The Great Fire obviously caused huge issues for the city. Not just in terms of dealing with the destruction, but also as you have rightly noted in terms of ownership of the areas destroyed. In the immediate aftermath of the fire there was a huge desire to rebuild as quickly as possible. The city was a mess, death tolls after the fire immediately rose alongside homelessness and the city became a much more dangerous place to be, with gangs taking to pillaging and even murdering within the burnt out remains. The King and Parliament wanted a new city built quickly, but also desired it to be a place of ‘Beauty’. Many plans were put forward to restructure the city, with three main plans taking prominence, by Wren, Hooke and Evelyn. These were submitted in the weeks following the fire and all involved a restructuring of the city, mostly around some sort of grid system. It became clear quite quickly though that due to the huge amount of private ownership of property in the city, this was going to be almost impossible. For centuries the ownership of building had been steadily complicated by leasing, letting and sub letting of property. In February 1667 a judiciary of 3 judges was set up , known as ‘The Fire Court’. It’s job was to settle disputes and allow rebuilding to start as soon as possible, and they heard many hundreds of cases. By February of 1667 it had also become apparent that the utopian designs of a restructured city were too fantastical and they were cast aside in favour of a few key changes. Streets were to be widened, a forty foot gap was to be left along the river front, some churches were to be demolished and trades which were deemed to be likely causes of fire were moved from high risk areas. The biggest change of all though was that buildings had to be made of brick and stone. This left us with the majority of the actual street pattern remaining the same.

In terms of temporary accommodation, with an estimated 70,000 made homeless this was no small feat. People in the suburbs of London were beseeched to offer lodging and send whatever food they could, and the open spaces around the city were effectively turned into ramshackle camp sites, with orders given the day after the fire for canvas to be sent to Moorfields for the construction of tents to house thousands of people as well as ships biscuits being handed out to feed them. We also know that life returned to the city quite quickly, with shacks being erected to serve as shops for what little stock had survived and theatres just outside the city (Drury Lane for example) being reopened by December 1666. The staking out of the street pattern was actually undertaken very quickly by city surveyors and took around 9 weeks to complete. We are told that by the end of 1667 150 houses had been rebuilt, and the city was 1672 the majority of construction work on new houses had taken place

I’m no expert on the intricacies of building regulations in the 17th century but I hope this goes some way to answering your question.

Please excuse any typos, I’ve had to write this on a phone as my laptop is currently out of action.