Typically, a cellar is something that is designed and built into a house from the outset. Adding one retrospectively is going to be hugely expensive.
Spiral Cellars offer a solution for those wanting to retro-fit a wine cellar into their home. A spiral cellar is a watertight, pre-cast cylindrical system that is sunk into the ground. It can be located anywhere from kitchen to conservatory, workshop to study. It can be installed into an existing ground floor room, or incorporated into the build of an extension or new property.