As the solution, the "Tilt Beam" which spans 12 meters over the terrace, is introduced. The original purposes of this "Tilt Beam" are to avoid people falling off and to protect the family�fs privacy. An ordinal vertical low wall is enough for these purposes, but such kind of wall would make the open-air terrace dark and harm the spacious feeling. The "Tilt Beam" is lifted slightly above the floor to form a slit of the light and tilted outwards to make the surface of the beam brighter with sunshine.