Making Interior Changes: Building a Wall

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The process of building a new partition wall can be simple or complex, depending primarily on where the wall is positioned. H the wall runs perpendicular to the existing ceiling joists, it’s easier to install than if it runs parallel. And if the new wall runs both parallel to and between two joists, the job may involve cutting into the ceiling and wall surfaces to add blocking.

The first step in building a new wall is to determine its proper location. If the wall runs perpendicular to the ceiling joists, nailing through the finish surface to the joists is no problem. If the wall runs parallel to the joists, locate it directly beneath a joist whenever possible.

Attaching Walls

If the wall must run parallel and between the joists, install nailing blocks to secure the wall to the ceiling. If you have access to the attic above the room, nail in short lengths of 2 by 4s between the two joists. Space the blocks 32 inches apart if possible (48 inches is all right).

If you don’t have access above the room, there are several alternative methods for securing the wall to the ceiling. One is to drill through the top plate and finish ceiling and use toggle bolts to connect the two. Space these about every 24 inches. This method isn’t recommended for walls that include a door.


Attaching Partition Walls to the Ceiling: If the new top plate is directly beneath joists use nails; if not use toggle bolts. Install nailing blocks between joists in the attic from above or strip the ceiling and put them in from below. Nail the top plate of the new wall to the middle the 1 by 6, leaving a nailing surface for ceiling covering on each side. Cut 2-by-4 blocks about 13½” long, insert them through the openings, turn them perpendicular to the joists, and hold them In place with fiat-head screws. Cut openings about 3” wide along the ceiling where they’ll be covered by the new wall. Cut 2-by-4 blocks about 13½” long, insert them through the openings, turn them perpendicular to the joists, and hold them In place with fiat-head screws. Screw the top plate of the new wall to the blocks.

1. Remove the bolt from the toggle, put a large washer on the bolt, and screw it back on the toggle.

2. Drill a hole through the top plate and ceiling large enough to accept the toggle. Fold the toggle, insert it through the hole, and let it snap open above the ceiling.

3. Tighten the screw to pull the toggle against the upper surface of the ceiling covering.

A second technique requires stripping away the ceiling surface between the joists and toe-nailing the blocks in position. This method is practical only if the ceiling is to be removed anyway With the ceiling surface down, you will need to provide a nailing surface for applying wallboard. This can be achieved by nailing a 1 by 2 or 2 by 4 along the edge of the joist, or by setting the nailing blocks back 3/4 inch and inserting a 1-by-a board above the top plate (see the sketches for details).

A third technique involves slightly less work but does not create as strong a connection. Cut several channels through the ceiling surface where the new wall will be positioned. Each should measure 3 inches wide and 13 1/2 inches long. Space the openings 32 inches apart. Insert a 2-by-4 block 13 1/2 inches long (or 1 inch shorter than the space between joists) and turn it 90 degrees so it’s perpendicular to the joists. (If you insert the block end- first, the opening can be smaller.) Hold the block with one hand, and drive two wallboard or wood screws through the ceiling into the ends of the block. Then use wood screws to attach the top plate to the blocks. The width of the new wall will cover the channels—only the screw holes in the ceiling surface need to be patched.

Alter attaching the ceiling blocks, locate the existing studs in the sidewalls. The new wall must be nailed to a stud or blocks installed between studs. Two blocks for each end of an 8-foot wall are generally sufficient. Toggle bolts can also be used.

Framing Walls

Interior partition walls are normally framed with 2-by-4 lumber. To frame a bathroom wet wall, you may need to use 2-by-a studs to accommodate the size of the drain- waste-vent lines. Begin by measuring the length of the new wall. Because the walls and ceilings in an older home may not be square, measure along the floor and ceiling. Also be sure either to remove baseboard and ceiling moldings beforehand or chisel out an opening wide enough for the new wall.


Framing and Attaching Stud Walls: Existing studs; Toenail new nailing blocks between studs; The end studs of your new walls must be secured by nailing them to a stud in the existing wall or to blocks you nail between the existing studs. Nail end stud of new wall to top plates, sole plate, and new blocks. Sole plate marked for toe-nailing of studs.

Next cut two 2 by 4s to serve as top and sole plates. For a nonbearing wall, a single top plate is sufficient. Lay the two plates side by side and mark of f the location for the studs and any door openings. Although some codes allow 24-inch spacing for nonbearing walls, the preferred spacing for all partition walls is 16 inches on center. Use a square and pencil to indicate the location of each stud. If the position of the last stud at the end of the plate is less than 16 inches, fine. Don’t change the layout to make the studs come out even.

Nor should you change the spacing for a doorway. Once you see the layout on the plates, however, you may decide to move the door location slightly to take advantage of the normal stud spacing. (For information on framing a door opening, see this page.) Because you are building a completely new wall and can guarantee the rough door opening will be square, allow 1/4-inch in stead of 1 1/2-inch clearance on each side. To simplify cut ting out the opening when the sole plate is nailed to the floor, turn the sole plate over and cut through half its depth at the door location.

At two points along the ceiling, mark the location of the edge of the top plate and snap a chalk line. Use a plumb bob to mark the position of the sole plate directly beneath the top plate and snap a second chalk line. Nail the sole plate to the floor with 10d nails every 16 inches. As a precaution, check in the basement first to be certain you won’t puncture any plumbing or heating pipes. Don’t nail between any door opening. If the floor is badly warped or uneven, shim the low spots beneath the plate.

Make several measurements between the ceiling and floor. Be sure the measurements take into account the top plate. It is easiest to temporarily lay the top plate on top of the sole plate while making the measurements. If the floor-to-ceiling height varies more than 1/8 inch, measure and cut each stud separately. If the dimensions vary only slightly, cut all studs to the same length.

Next lay the top plate on edge and nail into the end of each stud with two 16d nails. If a doorway is included, nail in the trimmer studs, header, and cripple studs. With a helper, raise the entire framework with the studs dangling beneath, position the top plate along the chalk line, and nail to the ceiling joists or blocks with 10d or 16d nails. The size of the nail depends on the ceiling surface, but nail into the joist at least 1 inch. If necessary, use shim stock to fill any gaps. Use a plumb bob to guarantee that the new wall is plumb. Once the top plate is secured, attach the two end studs to the sidewall framing with 10d nails. Then toenail all other studs to the sole plate, first checking each stud for plumb.

Short sections of 2 by 4s nailed between the studs may be required as fire-blocking. Check your local code: the blocks may not be required. They take time to install, but add rigidity to the wall and provide an additional nailing surface for wallboard and paneling.

If you are erecting two or more walls that intersect at right angles, reinforce the corner assemblies. This is necessary for greater strength and to provide a nailing surface for applying wallboard and paneling. The easiest technique is to use two full studs with three short 2-by-4 blocks nailed in between them. Full-length studs can also be used. (See the sketches for corner assemblies.)

An alternative technique. If the ceiling or sidewalls are badly warped or not square, or if there is no room to lift up a built wall, your best bet is to nail in the top and sole plates first. Then measure, cut, and toenail each stud separately. This approach also works well if you have no one to help lift the framework in place. The only real difference is toe-nailing the studs both top and bottom, rather than end nailing to the top plate first.

A second alternative. If you have sufficient floor space and a helper to assist with lifting, you may be able to frame the wall completely on the floor and then stand it up. But first determine it the walls and ceiling are square. (If they aren't , use the first technique described.) This technique generally works best with shorter wall sections that don’t extend the entire width of the room. Otherwise you’ll have trouble getting the wall in position without jamming the ceiling and sidewalls. If you do decide to use this technique, cut the studs 3/4 inches less than the height from floor to ceiling. This allows for the thickness of two plates plus 1/4 inch for clearance. Once the wall is raised in place, wedge shim stock between the top plate and the ceiling. Then nail the top plate to the joists and the sole plate to the floor.

Wiring New Receptacles

After the wall is framed and nailed in place, rough in any electrical systems involved. If the local code requires this work to be done by a licensed professional, now is the time for the electrician to arrive. If you’re able to handle the work yourself, be sure to secure the appropriate permits before you begin.

In many cases all that’s necessary is one or more electrical outlets. This section describes how to extend an existing electrical circuit to provide outlets for a new partition wall. It isn't within the scope of this guide, how ever, to provide a complete discussion on all aspects of wiring. If your project requires more detailed information, consult our Basic Wiring Techniques.


Adding Wiring to an Existing Wall: Cut away a small section of wall covering that will be covered by the baseboard.


Putting Wiring in a New Wall: Existing outlet power source for extended; Cable concealed behind baseboard.

Extending an existing circuit. The following summary covers the steps in adding outlets and switches to a new wall. The purpose here is to help you see what’s involved so you can relate the wiring process to other remodeling operations.

First determine where new outlets should go. Electrical codes generally specify the approximate location of new outlets and switches. For example:

• Any wall more than 2 feet in length should have at least one outlet.

• No point along a new wall should be more than 6 feet from an outlet.

• Outlets should be 12 to 18 inches above the floor.

• Although not specified by code, it’s common for lighting circuits to have 10 to 12 outlets and for small-appliance circuits to have 6.

• Switches should be 48 inches from the floor and on the latch side of a doorway, as well as at each entrance to a room and at both ends of hallways and stairs.

Your next step is to find a source of power to tap into. For one or two new outlets, this usually means the closest outlet, junction box, or source-fed switch of an existing circuit. For larger extensions, it may mean running back to the breaker panel. Avoid these sources:

• A single-appliance circuit. Whether 120 or 240 volts, it's intended to serve only one fixed appliance, such as a dishwasher or furnace motor.

• A switch at the end of a loop or in the middle of a three-way switch loop.

• A junction box with wiring from several circuits.

• A potentially overloaded circuit. You can calculate the future electrical demand by adding up the total watts anticipated and dividing by 120 volts. The quotient, the number of amps potentially demanded by the circuit, should not exceed the rating of the circuit breaker (usually 15 amps).

Once a source is located, plan the most accessible route for running cable to the new outlets and back to the source. Possibilities for routing the cable include:

• Behind baseboards, either in existing gaps or notches cut into the lath and plaster.

• Under the floor, as long as there is a crawl space.

• In an accessible attic.

• Around a doorway in a groove behind the casings. Most routes will involve fishing wires through walls or floors at some point, but do choose the path with the easiest access.

Installing the system. First install outlet and switch boxes in the new wall. Mount them with the front edge extended /2 inch beyond the studs so the edge will be flush with the final finish wall.

Then run new cable between the boxes and back to the source, drilling through studs, sole plates, or top plates where necessary Be sure to staple the cable every 4 feet and within 12 inches of metal boxes and 8 inches of plastic boxes. Leave 8 to 10 inches of cable within each box.

Before running cable into the final source, which is usually an outlet or junction box, turn off the electrical circuit. Then run cable into the old box through an unused knockout hole. Leave 8 to 10 inches of cable for connecting to the old receptacle. Before turning on the circuit again, install all new receptacles and fixtures and connect the new run to the existing power source. Re store power and double check your work with a voltage tester and polarity tester.


Running Cable Under the House: Drill a ¾” hole 2.5-3” inside a pilot hole (drilled from above).


Running the Cable Through the Attic


Running the Cable Under the Floor; Running Cable in the Attic: Joists

Thursday, March 24, 2016 12:40 PST