I recently spent Shabbos in an area where there was no community eiruv. The house I stayed in had a deck that one could walk out onto from the second story of the house. The deck was enclosed by walls which formed a reshus ha'yachid adjacent to the house. The deck was supported by four poles which were planted in the ground outside. A door from the first floor of the house led out to the region directly below the porch. My question is, is it permissible to walk out the first floor door and carry in the area under the porch? Specifically, can one argue that the walls of the porch above extend downward (gud achis) to create halachic walls that enclose the bottom region as well and permit me to carry in this region?