How Do You Install a Wall in a Pre-Existing Basement?

Perimeter Walls

• 1

  Nail a 2-by-4 top “plate” perpendicular across the bottom of the joists at an outer wall; nail plates on the bottom of side joists. Plates must form 90 degree corners.

• 2

  Drop a plumb line from one end of the top plate on its inside edge and mark the floor. Repeat this marking procedure at the opposite end of the wall and as many places along the plate as necessary to draw a line or snap a chalk line for the inside of the floor plate.

• 3

  Spread a line of waterproof construction cement along one side of a two-by-four and set it along the line so its inside face rests on the line. Wiggle the floor plate a bit to create a sufficient seal between floor and plate before nailing the plate to the floor. Check to ensure the plate is plumb against the floor and that it is directly below the top plate all along the wall.

• 4

  Mark the floor and top plates every 16 inches and check to ensure that the marks are plumb with your plumb line.

• 5

  Measure and cut the 2-by-4 studs to install between the floor and top plates 16-inches on center, meaning that the marks on the plates hit the center of the 2-inch side of the two-by-four.

• 6

  Attach the studs to the top and floor plates by toe-nailing, or driving nails diagonally, through the end of the stud into the plate from both sides.

• 7

  Insulate perimeter walls with foam board. Use the appropriate insulation for your climate -- damp soil and cool climates require board with foil facing pointed out and hot climates need foil on the in-side. Use boards that can be trimmed for 16-inch on center spaces and secure boards with foil tape or spray foam.

• 8

  Cover studs with wallboard or waterproof green board, tape and paint.

Interior Walls

• 9

  Build frames for interior walls flat on the floor. Lay out the top and bottom plates on their 2-inch sides and mark 16-inch centers along their lengths.

• 10

  Measure the height of the ceiling in several places along the length of the proposed wall because floors are uneven to allow for drainage. Cut the studs 4 inches shorter than the shortest distance to allow for the thickness of the plates.

• 11

  Nail studs 16-nches on center. Because you are building your wall flat on the floor, you can nail through the plates straight into the studs. Check to ensure all corners are square as you nail studs.

• 12

  Stand your wall up and tap the plates on the short end into place. Check your starting point to ensure that your wall is plumb and nail the plates into the rafter and floor.

• 13

  Steady the wall with chairs or a cooperative assistant as you nail in the top plate along or across rafters. Drop a plumb line at the end of the wall and put shims under the floor plate to keep the plate from moving as you nail it from that end. Add shims along the plate as you work back toward the short end of the wall, nailing the top and floor plates as you go.

• 14

  Plumb and run electrical conduit before covering interior walls. They do not require insulation.