Running wire through existing walls

Routing wire through walls in a finished home can often be more difficult than working in new construction. But there's a range in difficulty — running short lengths of cable down from a wall-mounted set is pretty straightforward, while running cable for a multi-room system may be more time- and labor-intensive. As you read, think about what kind of installation you're planning, and your comfort level with tackling some of the potential obstacles in your home.

Cutting and drilling into your wall or ceiling

Always inspect as much as possible without making a hole. Explore your crawlspace or ceiling in an unfinished segment of your basement. Try to detect which way joists run and where empty wall space between studs might be. By inspecting from your crawlspace or attic, you can identify which wall locations are empty of water pipes and electrical wires. We also recommend purchasing a high-quality stud finder that can distinguish between different types of obstacles behind your walls, including studs, AC cables, and pipes.

Of course, you can't know what's behind the wall with absolute certainty. You must be prepared to cut and patch exploratory holes. To minimize that work, we recommend drilling small "pilot holes" to explore behind your walls. Use a sturdy piece of wire, like a bent coat hanger, to find nearby obstacles. Be sure to shut off power in the area where you'll be drilling your pilot hole, and use caution so you don't plunge your bit into a pipe or electrical conduit.

Use a sturdy wire (such as a bent coat hanger) to explore your pilot holes.

Cutting drywall
After you've confirmed that all of your component locations will work, traced the templates, and made any other preparations recommended in the owner's manual, you can begin cutting drywall. If you're creating a rectangular hole, start by drilling two small holes in opposite corners; if it's round, drill two small holes on opposite sides. Next, using your drywall saw, start from one hole, and work around the outline to the next. Use a hand-held drywall saw (not an electric one) and cut slowly. Cut the drywall in one piece, on an inward slant, so that it's easier to patch later if necessary. If you don't need to patch the hole, just remove any excess material before installing the speaker. Be sure you know what's behind the drywall before you cut.

For more information on choosing and confirming locations for your in-wall gear, see our in-wall speaker installation guide.

Plaster and lath walls
If your house has plaster and lath walls or ceilings, installing your own in-wall wiring will be more complicated. Plaster tends to crack and crumble easily, so you should be prepared to do some touch-up work. We recommend running out-of-wall wire, and using carpets, cabinetry, etc. to hide it. See our article on home A/V cable management for more ideas.

Wiring tips and tricks

What if you can't avoid a hidden obstruction?
You'll probably encounter some in-wall obstacles while routing your cables, such as additional bracing or a fire block. If that happens:

• Use your stud finder to estimate the position of the block behind the drywall.
• Drill small pilot holes and use a piece of "L" shaped wire to determine the dimensions of the block.
• Using your drywall saw, remove a rectangular piece of drywall around the obstacle. Cut on an inward slant so that it's easier to patch the drywall when you're done.
• Notch the block or drill a small hole for your wire. If you notch the block, don't forget to cover it with a nail plate.

To route wire through a hidden obstruction: (A) Cut a rectangular piece of drywall around the obstacle. (B) Notch the block or drill a hole for the cables. Use your fish tape to route the wire through the hole.

Fishing cable through insulation
Insulation is most commonly found on exterior walls, but you might run into it when fishing wire through interior walls too. The key here is not to fish the wire through the insulation, but around it.

Many types of insulation will have a paper or plastic covering. Try to fish your wire between that covering and the drywall. Alternatively, fish the wire along a stud, using the stud as your guide. In this case, if you have fish tape that's wound on a spool, keep the tape curved in towards the surface of the stud, so that it's less likely to stray into the insulation.

You can also check your local hardware store for different kinds of fish tape designed to be more effective with difficult runs like these. Note: Wear gloves and protection for your mouth, nose, and eyes before handling insulation that contains fiberglass.

Routing wire through an unfinished basement: (A) Cut the holes where the wire will enter and exit the wall — for example, where a wall plate and in-wall speaker will be installed. Next, drill two holes in your basement ceiling to route the wire. You can either measure the distance to the wall plate and speaker from an adjoining wall, referencing a copy of your blueprints, or measure the distance from a visible landmark that runs straight through the wall to the floor below, such as a plumbing pipe. (B) Once you've drilled the holes, use a fish tape to pull the wire up to the wall plate location. (C) Next, fish the wire up to the speaker location.

Routing wire horizontally along a baseboard: Carefully pry off the baseboard with a small crowbar. Cut the wire channel by scoring and chiseling the studs (be sure that the baseboard will conceal the channel). Fish your tape from one hole to the other and pull the wire through. Tuck the wire into the channel and install nail plates at each stud. Re-install the baseboard ? no drywall patching required.

Routing wire around a door frame: Carefully pry the molding away from the doorway using a chisel, small crowbar, or putty knife. Run the wire between the frame and the jamb. (You might need to chisel out channels for the wire in the frame, so that it doesn't get pinched or compressed when you replace the molding.) Reattach the molding, being careful not to damage the wire.

Routing wire horizontally through the wall: If you're working with a relatively short wire run, cut a narrow channel of drywall in one piece, using a utility knife. Ensure that the channel begins and ends at a stud, so that patching is easier afterwards. Drill holes in the stud with a spade bit. Pull wire and patch, using the piece of drywall you cut out. For longer runs, cut a series of smaller wire channels, each beginning and ending at a stud.

Routing wire from a J-box to an in-ceiling speaker: (A) Cut the holes for the speaker and the J-box. Cut two adjoining holes at the wall/ceiling junction, exposing the beams at the top of the wall, or "top plates." Fish down to the J-box and attach the wire to the fish tape. Pull the wire through the hole in the top of the wall, and remove it from the fish tape. (B) Fish from the speaker hole to wall/ceiling hole. Re-attach the wire to the fish tape and pull the wire to ceiling speaker hole. Notch the top plates and insert the wire in the notch. Affix a nail plate and patch the holes.