How to add a new cable box to an existing stud wall

Question

I need to wire in a new speaker volume adjuster and box into an existing stud wall. My worry is I am not sure if the speaker wire will be able to get to where I need it to go. This is because I am worried that the stud wall wood will get in the way.

If this were not yet plaster boarded, I could pre-drill any needed holes. The wall is freshly painted, so the less cutting the better.

How likely is it that the cable will be able to drop vertically down the wall if I insert it at the top of the wall? If not, what do I do to get the cable where I need it?

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What are your suggestions?

Answer 1

If you have access to the top plate of the wall and the wall has no insulation, that's super easy:

• Get a low-voltage, existing work rough-in box from the hardware store.
• Cut a hole in the wall for your box. Make sure you are at least a couple inches away from a stud, although dead center between to adjacent studs makes the process easier.
• Drill a 1/2" hole in the exact middle of the top plate.
• Drop the cable down through the top plate.
• Stick your hand in to the wall through the hole you cut through the drywall and grab cable.
• Done!

If the wall is insulated, the procedure differs based on what kind of insulation you have. If the insulation is soft, such as blown-in cellulose or batting, then instead of just dropping the wire in you need to use something stiff to push through the insulation. The proper tool would be a fish tape or similar, but if the distance isn't too long you could use a hanger or similar.

If the insulation is rigid foam or sprayed in foam then you will need to carve a channel through the insulation. The easiest way to do that is with a long drill bit designed for drilling through cross-members inside a wall. The only difficult part is knowing where the drill bit ends up because they don't always travel straight. I've had success drilling the initial hole through the top plate almost adjacent to a stud, and aiming the long drill bit towards the stud. (Not at the stud; towards and long the stud.) The drill bit can then follow the stud down the wall. That should make it easier to locate the cavity you've drilled out.

And don't forget that repairing drywall is pretty easy in the grand scheme of things. If you need an extra hole(s) then don't worry about it.

When you're all done, make sure to fill the hole you drilled in the top plate with fire stop caulk or foam.

Answer 2

Usually in stud walls, the studs are all parallel and vertical. This means that you have vertical pockets between the studs (from floor to ceiling) to work with unless your wall is an outside wall -- in this case, the pockets may be filled with insulation.

In the non-insulated case, you can drop your cable right down the pocket. If insulated, you may need to resort to a fish tape in order to sneak between the insulation and the wall. I would suggest using a stud-finder to... find the studs, or even a strong magnet to locate the nails or screws going into the studs; this way, you can choose a spot in the center of a wall pocket.

Answer 3

Walls can have horizontal 2" X 4"'s between studs; and, there is no easy way to find out. Some folks can tap on the wall about midway down and based on the thump sound ascertain whether there's a cross piece behind the drywall. Me, I have to drill a hole through the top plate and run a fish tape (search for "steel fish tape" at Lowe's or Home Depot) down inside the wall cavity to find out. Keep in mind that the wall likely has insulation which will impede the fish tape. But, you can still run it down to a hole in the wall. Just make sure you drill the hole between the two studs in the outlet hole's cavity. To do this, what I do is take a coat hanger wire and push it through the ceiling right close to where I want the hole to be drilled. Then I go in the attic and find the coat hanger wire sticking up. Make sure you stick about 15" through the hole to make it easy to find. And drill the hole big enough to make running the fish tape and wire easy. Once you run the fish tape down the wall you still may have trouble finding it in the cavity, especially if there is insulation. I usually have to run my hand inside the outlet hole and feel around until I get it. It helps if the hole was drilled in the middle between the two studs. A mirror and a flashlight can alsobe useful, as well as bending the coat-hanger wire to form a "c" and using it to try to hook the fish tape. Good luck.