Framing an Interior Wall

Most wall framing is done with 2x4 lumber but new interior walls may be built using 2x3's. This is common when a new wall is added as a partition or to build a new closet in an existing room. Working with 2x3's is easier and will cost less than 2x4's and the smaller size takes up less space. The only drawback to using this smaller dimension lumber comes when installing a door or an electrical box. A door jamb and most outlet boxes will usually be too wide to fit flush in the opening. This might not be a problem with a closet where the overhang can be concealed inside, but with a room partition the effect would not be acceptable.

A basic wall frame includes the soleplate, top plate and studs. One 2x4 is used to form the soleplate and in the case of existing construction, two 2x4's are stacked to form the top plate. Because a new partition is just a divider and not a load bearing wall it can be built using just one piece of lumber to form the top plate.

In the United States studs are spaced 16 inches apart along the two plates with the center of each stud set at each 16 inch mark. This is done to accept four foot sheets of building materials like drywall, paneling and plywood.

Beyond the basic stucture of studs and plates, a door may also be built into an interior wall. Door framing will include king and jack studs to support the sides and a header and cripple studs to support weight over the door opening. The frame should be built to accommodate a door with the soleplate in place for stability, the plate can be cut out after construction is complete. See Framing Doors and Windows for detailed instructions for building a door frame into an interior wall.

Measuring for a New Wall Frame

Measure the space from end to end where the new wall will be built. Also measure the height of the ceiling in several places along the length of this space. In most cases the ceiling height will vary slightly along the length of a room. Find the shortest measurement from floor to ceiling and build your new frame to this height.

Subtract 3 inches from the ceiling measurement to get the actual length of the studs. The height of most existing ceilings will be over 8 feet, requiring the use of 10 ft dimension lumber in most cases. Divide the length of the new frame by 16 inches to determine the number of studs required. For the 16 foot wall pictured here, 14 studs will be needed. Six studs for each 8 foot module and 2 extra as the starting studs.

Build a new wall frame in manageable modules. For instance, for our 16 foot structure, we can build two 8 foot sections and join them to form the whole frame. Use the length of the new wall to determine how many 2x4's will be required for the top and soleplates. If your measurement is twelve feet or a little under (which is a common room size) you can use 12 foot 2x4's for your plates to avoid breaking up the structure into more than one module. If your space is longer than 12 feet, use 8 foot 2x4's and join each section together.

Building the New Wall Frame

Measure and mark the ceiling where the new frame will be erected. Use a square set against an adjacent wall to form a 90° angle with the new structure. Mark the ceiling with a straight line and hold a plumb bob at the mark to find the corresponding point on the floor. Mark the floor at this point and use the mark to position the new frame. Lay a 2x4 on the floor and use the square to line it up. Draw a pencil line along the 2x4 and use the mark when setting the new structure in place.

Build the wall frame with the lumber laying on edge, on the floor where it will be erected. Lay out the top and soleplates side by side and measure starting from the end. Mark both boards every 16 inches. Separate the plates and lay the studs between them so the centers align with each mark. Nail the plates to the studs using two 16d or 20d nails driven through the plate at each stud.

At the floor mark, nail a 2x4 block to the soleplate of the adjacent walls. Or if the floor is unfinished, you can nail a couple of blocks to the floor along the line where the soleplate will fall. Use the blocks to hold the bottom of the new frame in place while lifting the top plate to the ceiling. Wedge the frame between the ceiling and floor using a small sledge hammer to tap the plates as needed to draw it up plumb.

Set the new frame plumb and square using a level held against the edge of the studs. Tap the plates one way or the other until all your studs read plumb by the centering of the level bubble. Check for square at any adjacent walls using a square. Secure the new structure in place driving 16d or 20d nails or 3 inch screws, through the soleplate and into the floor and ceiling joists.

If the new wall runs parallel to the ceiling joists, instead of perpendicular, try to place it so it falls directly below one of them. The top plate can then be nailed to the joist all the way across the room. Otherwise, 2x4 blocks should be added between the joists in the ceiling, perpendicular to the new frame, and the top plate secured to them. Finish installing the new structure by fastening the end studs to the top and soleplates of the adjacent walls.