head perimeter frame member the sill perimeter frame member also includes a glass panel accommodating portion adapted to receive a glass panel and an interior component that allows the airloop wall unit to be attached to the building as described in u s pat no 8 001 738 the adhesive 24 also acts as the air seal of the unit 10 the water seal 23 around the exterior edges of the vision glass 11 is provided to create the airloop space 25 between the water seal 23 and the air seal 24 air holes 31 are provided in the sill frame 13 such that the airloop space 25 can be pressure equalized to the exterior air fig3 a shows the fragmental cross sectional details of the sill frame taken along line 3 a 3 a of fig1 a in some embodiments of the window wall system the jamb frames 14 and 15 may have the same profile as the sill frame 13 and are the major structural members for transferring the wind load on the unit into the base and the ceiling tracks therefore the jamb frames are preferably continuous from the base track to the ceiling track in some embodiments the jamb members do not include an interior portion that allows them to be attached to the building in those embodiments the airloop wall system is attached to the building primarily through the head and sill perimeter frame members once the perimeter frame members 13 14 and 15 have been profiled for the vision glass panel 11 the perimeter frame members may be supplemented to accommodate a thinner spandrel pane 11 a this can be accomplished.