The official website does not address when the porch covered area might have been added, but it does not appear original. It may have been added to protect the original wall, where wooden beams reinforce the stone and whatever the plastering material is. Need more research.
The wooden beam, or courser, would have been difficult to replace. Perhaps it only survived because of the protection of the porch roof?
The windows are tiny, perhaps to serve the defense needs of this remote location.
History of Santa Coloma.
The original people here may have been Basque. There are traces of Celts, Iberians (some say these relate to very early Hebrew roots, migration to the Caucasus, and westward. The language is not Indo-European, see start at http://www.britannica.com/EBchecked/topic/280571/Iberian; and interesting takes at http://www.hebrewrootssc.com/The-Lost-Tribes.html), and something called Andosinos here as well. See Google book, One Europe, many nations: a historical dictionary of European national groups.
That site's wording is reflected at other sites. The area was part of the Roman Empire, and when the Empire fell, invaders such as tribal Alans, Visigoths and Vandals, bent for Spain, passed through and some probably stayed. See Andorra history at http://www.medinnus.com/andorra/history.html
Then came the Moors, sending the lowland occupants, including Christian peasants, of both France and Spain into the mountains.
The entry arch is detached and at a distance from the main church. The tower was added later, in the 12th Century, see andorra.ad site, and again seems to serve a defense purpose as well. Tiny apertures at ground level, broader -- even enabling projectiles and arrows? and for observation - above.
The church is deep in the valley. Could someone please date the porch columns and roof material, also wooden?
Enter the church and look down and back out: The old stone threshold area looks original, the door opening to the outside very new.