A study of seismic vulnerability allows to know the conditions under which is a building in front of the presence of a moderate earthquake, this paper grade is focused on the homes of one or two floors built by their owners before the effective date decree 1400 of 1984, in this study the method of quick observation or ATC 21, which is an inspection from the outside of the houses, their structural conditions and nonstructural existing, is used ATC 21 method sets a level seismic vulnerability calling the building between a, significant, high and very high minimum vulnerability. Solutions to the deficiencies found, based on the standard NSR10, specifically the title E, providing a proposal for safe, affordable housing raised.