In Galera alone, it is reckoned that there have been around 1,000 cave homes excavated in past centuries. Many of these ancient cave houses will not be restored because they are either inaccessible, have no services, have unclear or difficult ownership, or are too small.
Cave homes and houses can only be built when certain conditions are right.
The weather in this locality also provided the incentive to build the cave homes in the first place. The climate here is hot and very dry in the summer and cool in the winter, especially at night. Cave homes have a relatively constant temperature of around 16 to 20 deg. C. summer and winter, this natural temperature is a result of the surrounding rock. They certainly do not require air conditioning and only moderate heating in the winter, one log fire usually being sufficient. A few caves do not have any heating whatsoever yet remain warm on the coldest nights.
Additonally the rock needs to have sufficient strength to avoid the risk of collapse even after many years. In Galera the cave houses are dug into highly stratified forms of gypsum or limestone, most often with a strong and relatively hard layer of rock, one or two meters thick, forming the roof.
Many old cave homes before modernisation, were quite low (their inhabitants at the time of building being considerably shorter than today). In almost all cases the additional height needed is gained by excavating the floor, it is rare for the roof or support walls to be touched.
In other places, such as Guadix or Huéscar, the caves are dug into non stratified forms of conglomerate rock (a compressed mixture of sand, mud and pebbles) and mudstone. The strength of the roofs of these caves is provided by their arched shape.
