Things You'll Need
Heavy-duty, 4-inch blue, concrete screws
Heavy-duty concrete anchors
Hammer drill and bits
Compound miter saw
Pneumatic nail gun
3-inch pneumatic nails
4-by-8-feet gypsum wallboard sheets, 5/8-inch thick
Corner bead tacks or nails
Extending an existing wall gives two adjacent areas a well-defined separation. Perhaps it will extend a wall to create a hallway effect, such as in a main entryway that immediately opens out into a living room or close off a space that already has three walls to make it a fully enclosed room. Extending a wall begins with structural framing and ends with a finished, new wall that blends seamlessly with the old.
Framing the Wall
Measure the desired length of the wall extension from the existing wall with a tape measure. Mark the end of the wall extension on the floor with a pencil. Round off at the nearest 12 inches and if possible to the nearest 4 feet to maximize the use of the sheets of gypsum wallboard without awkward cuts.
Measure the height of the wall extension with a tape measure and write it down.
Cut two 2-by-4s to the wall's length measurement using the compound miter saw. This will form the wall's top and bottom plates.
Divide the wall's length measurement by 12 for the exact number of vertical studs needed for the wall.
Cut the amount of vertical, 2-by-4 wall studs needed for the wall, plus two extra ones, with a compound miter saw. Subtract the 2-inch thicknesses of the wall extension's top and bottom plates from the wall's height and use this measurement for the cut.
Align the top and bottom plates parallel to each other, spaced and standing on their 2-inch-length sides.
Insert the two end, vertical wall studs in between the wall's top and bottom plates at both ends, laying them on their 2-inch-length sides.
Nail through the top and bottom plates into the top and bottom of each vertical wall stud with a pneumatic nail gun and 3-inch pneumatic nails.
Insert and evenly space the rest of the vertical wall studs between the wall's top and bottom plates. Nail them in place.
Installing the Frame
Raise the extension wall's frame, and align it flush to the existing wall. Level it widthwise and lengthwise. Leave a 5/8-inch flush gap so that the thickness of the gypsum wallboard will not protrude from the wall where it meets the old wall.
Screw the frame into the old wall's studs. Use 3- or 4-inch screws to connect the frame at several places along the end stud's height.
Align the bottom of the wall's frame to run smoothly parallel or perpendicular to the existing wall. Drill and screw the nails through the frame's bottom plate and into the floor. For concrete or tiled floors, drill anchor holes into the floor with a hammer drill and then screw the screws through the frame into the anchors in the floor.
Insert and nail another wall stud into the frame at both ends, flush with the inner side of the end stud to give the wall support and strength at the end.
Measure the width of the first gap at the end of the extension's wall frame that extends out into the open space. Cut three to five 2-by-4s to make cross pieces. Insert them horizontally, space them vertically and nail them into the studs. These pieces will give the open end of the wall extra structural support.
Cut and install the gypsum wallboard on both sides of the wall using a straightedge, utility knife, 2-inch screws and a drill.
Finish the wall with joint compound smoothed over paper tape at the seams and screw holes using feathering knives and then paint the wall extension to match the old wall.