How to Build a Bathtub Frame in an Alcove

Measure the height of the bathtub’s nailing flange. Push the bathtub into the alcove. Trace lightly the top of the nailing flange onto the studs on all three sides. Remove the tub.

Measure down from the marks the distance obtained for the nailing flange. Make new, darker marks, pressing the pencil against a speed square held against the stud, to show your ledger board location. Draw a V-shaped mark touching the center of the lower mark to indicate that is the correct level for your stud location.

Measure the distance between the side walls of the alcove. Mark a 1-by-4 board with this measurement. Cut the board to size on a chop saw.

Clamp the 1-by-4 to the studs on the back wall, top edge aligned with the ledger board marks. Screw two 3-inch galvanized deck screws through the ledger into each stud.

Measure, mark and cut a 1-by-4 to fit on the side wall without plumbing. Screw this ledger board into place as you did the first one on the back wall.

Cut two pieces of 1-by-4 for the remaining side wall, called the “wet” wall because the water supply line comes through it. Make each half the length of the ledger board, less 2 inches to allow passage of the drain-waste-overflow pipe. Screw the two half-boards in place on the wet wall, below the ledger line, creating a 4-inch gap in the middle of the ledger for the pipe. The free ends of the ledgers will project past the studs. Your alcove is now ready to accept the tub, which will be nailed to the ledger board.