Trenches were opened in the secondary _atrium_ (1) of _domus_ VII 15, 1-2, the so-called House of the Sailor. Trench B was placed at the centre of wall E and trench C in area N of the _fauces_, corresponding to house number 1. In trench B, below a crushed lava floor in use in 79 A.D., there were a series of overlying levels all containing the same material, thus contemporary with each other, which caused a rise in the floor level. This rise began with a beaten earth floor belonging to a dwelling that preceded the _domus_ VII 15, 1-2. In fact, the foundation trench of wall E cut this beaten surface. Below the latter were a further three beaten earth surfaces which seem to relate to a 3rd century B.C. house. Trench B did not reveal any walls on an east-west alignment that could have formed part of _cubiculum_ reflecting those present on side E of the main _atrium_ (b) of the house. Therefore, _domus_ VII 15, 1-2 seems to have originated as a house with a double _atrium_. Trench C revealed the foundations of the door jambs east and west of the north opening of the _fauces_: these cut directly into natural. From this foundation level up to the 79 A.D. crushed lava floor a series of overlying levels was revealed, containing the same material as was found in the levels used to raise the floor in trench B. In this sector no floor levels were found that could be attributed to an earlier dwelling. The data from the two trenches suggests that the raising of the floor level and the foundation of the House of the Sailor can be ascribed to sometime within the 2nd century B.C.