Measure away from the wall where the plumbing is to a point beyond the plumbing -- a couple of inches of space between the pipe and the wall is advised. For instance, if your plumbing stack is centered on a wall, measure toward the center of the room until you are past the pipe. Do this on both sides of the pipe, then connect the two measurements across the front of the pipe. When finished, you will have a three-sided box that goes around the pipes. Place tape on the floor where the framing is going to go.
Use the measurements from the floor to mark the ceiling for the top part of the framing.
Cut the base plates and top plates. Cut pieces of lumber to the measurements determined earlier. There are three top pieces and three bottom pieces of your bulkhead frame. Measure the distance from the floor to the ceiling and cut 4 pieces of lumber to that measurement. These are the vertical supports for your framing.
Attach the top plates. Install the top plates with wood screws. Depending on your ceiling in the basement, the plates will be screwed to either existing joists or drywall if you have a finished ceiling. Hang the plum bob from one of the outer corners. Where the bob falls to is where the corresponding base plate corner needs to be. Either make a mark on the floor or put the lumber in place. Repeat this for the other outer corner.
Attach the base plates. If your floor is concrete, use the hammer drill to drill through the base plate and into the concrete. Attach the plate with the concrete anchors. Use at least two anchors per plate section. Measure the distance from the floor to the ceiling and cut 4 pieces of lumber to that measurement. These are the vertical supports for your framing.
Install two of the vertical supports on the base plates on either side of the pipe so they are flush with the outside edge of the base and top plates. Attach them to the wall and plates with wood screws.
Install the outer two vertical supports in the same way. There is one support in each corner, flush with the outer edges of the base and top plates. Fix these in place with wood screws.