Q: When I replace windows, I set up interior vertical containment barriers that extend from floor to ceiling and completely enclose the interior area in which I physically work. If these barriers are set up at a distance less than six feet from the perimeter of the work surface, must I still extend the containment on the floor beyond the vertical barrier to meet the six-foot requirement?

No, provided that the vertical containment system consists of impermeable barriers that extend from the floor to the ceiling and are tightly sealed at joints with the floor, ceiling and walls (40...

No, provided that the vertical containment system consists of impermeable barriers that extend from the floor to the ceiling and are tightly sealed at joints with the floor, ceiling and walls (40 CFR § 745.85(a)(2)(i)(D)). This type of vertical containment acts as the functional equivalent of a wall for purposes of defining the work area.  If the vertical containment meets these criteria the floor containment measures may stop at the edge of the vertical barrier. 

Unlike permanent walls, however, vertical containment barriers are subject to all containment cleaning requirements including misting, inward folding, sealing, and proper disposal following the renovation.  A firm must also thoroughly clean an additional two feet beyond the vertically-contained work area.  Finally, during ingress or egress from the vertical enclosure, a firm must take precaution to ensure that dust and debris on personnel, tools, and other items do not escape the work area.