One key concern is the existing garage foundation. Often, it’s too shallow to support new walls, windows, or doors in place of the old garage door. If the height of the structure is being increased, deeper foundations may be required.
Your builder might need to excavate and pour new foundations, with a structural engineer confirming their suitability.

If you plan to change the roofline or add new doors, windows, or internal walls, these changes could affect the building’s structure and must be approved before construction begins.

Garages are not designed for warmth or comfort, they’re naturally draughty and uninsulated.
To meet current energy efficiency standards, all walls, floors, and roofs must be insulated, and new windows and doors must comply with thermal performance requirements.

Every new habitable room must have proper ventilation for healthy air circulation.
Windows should provide an opening equal to at least 1/20th of the floor area, with a clear opening of 0.33m² and minimum dimensions of 450mm x 450mm, plus trickle vents within the frame.

If your conversion includes a bathroom or toilet, ensure proper access to existing drainage systems. Some garages may have been built over underground drains, so it’s best to review your property plans to confirm their location before starting work.