Garages: planning and building regs.

Planning permission.

Planning permission isn't usually required, providing the work is internal and doesn't enlarge the building. Permission may be needed if it becomes a separate house, and permitted development rights have sometimes been removed, especially on newer estates and in conservation areas.

Check with your local planning authority. In Wigan, the council offers a lawful development certificate if you're unsure.

Building regulations.

• The floor. A damp proof membrane and insulation. Often the simplest answer is upgrading the existing concrete.
• The new wall. The old threshold is unlikely to have been designed to carry a wall, so a new foundation may be needed, down to undisturbed ground.
• Insulation. New walls and floors should reach 0.18 W/m²K, windows 1.4 W/m²K.
• Fire. If part stays as a garage, you need fire separation, and any door in that wall should be fire-resisting and self-closing.

Which route?

Wigan lists garage conversions as an example of minor work suited to a building notice, and says a full plans application is more cost effective.