How much do garage conversion drawings cost in London?

Where the cost is and is not

Our fee is £425 drawings + £150 survey (£575 total), and it sits in the middle of our range because the shell already exists. The survey measures the garage, the wall to the house and the door opening, and the drawings show the new floor build-up, the walls, the windows and the insulation.

The biggest money question is the council’s. Section 55 of the Planning Act says works that affect only the interior of a building, or do not materially affect its external appearance, are not development. A garage door replaced with a matching wall and window can fall either side of that line, so we draw the elevation to show what changes.

The three checks before you rely on “no planning”

The paper matters as much as the building.

First, the elevation. Changing the front of a garage is an alteration to the outside of the house. Class A allows alterations if the materials are of a similar appearance to the existing house, and the rules on conservation areas and Article 4 directions apply as to any other extension.

Second, the paper. A planning permission granted when the house was built may carry a condition that keeps the garage for parking. If it does, you need the council’s consent first. We read the decision notice for you.

Third, the certainty. If you want proof, a Lawful Development Certificate for proposed work costs half the planning fee, and the guidance says the council decides on the facts, not on neighbours’ opinions.

What building control wants from the conversion

Building regulations approval applies however simple the planning position is. Thurrock Council lists what the application must include: foundations to new walls, ventilation such as windows and trickle vents, a damp proof membrane to the existing floor, thermal details, and fire protection and stopping.

An attached garage has fire separation from the house today: Approved Document B asks for fire-resisting construction of at least 30 minutes (REI 30) between garage and house. Once the garage is a room, that wall and the door in it have to be reconsidered, and the drawings say how.

A detached garage is a separate case. The same council notes that one is exempt from building regulations only if it is under 30 square metres, not attached to the house, and either more than 1 metre from the boundary or made of non-combustible material. Converting it to a room removes that exemption.