From the Cellar Once you determine which walls you want the wires to run through, the next job is to find places in the cellar where you can drill access holes. Finding these walls can sometimes be a challenge, but there are usually clues — like pipes, heating ducts, and other wires — to lead you in the right direction. When you’re ready to drill, it’s a good idea to post a "spotter" upstairs. The spotter rests a hand on the floor and baseboard near where you’re aiming. If you miss the wall and the bit starts chewing into the baseboard, the spotter will feel the difference in the vibration and tell you to stop before you do any serious damage. Remember to drill slowly to give your spotter time to react. If the wall cavity you’re aiming for is near a doorway, the spotter can often feel both sides of the wall. Otherwise, I have the spotter feel the side that would be the most trouble to fix. When a floor is going to be carpeted or covered with linoleum or tile, you can sometimes cut a hole in the floor to help gain access to an area. If a room already has carpeting, you can sometimes drill carefully at the edge of the carpet with a small feeler bit. Be extra careful not to snag a carpet thread while drilling. You can unravel a large section of carpet in just a few seconds if you don’t pay close attention. If the baseboard sits off the wall a little, you can sometimes drill a hole behind it with a small feeler bit to help locate the wall. You can also lift shoe moldings and carpet strips and drill where the hole won’t be seen (Figure 4).

Figure 4. By removing the shoe molding at the edge of a carpeted room, you can drill an inconspicuous hole through the floor.

On an old wood floor that has not been refinished recently, there is sometimes a small crack between the boards that you can fit a small drill bit in to give you a reference point to help find the wall. Always remember to patch these small holes into the cellar. You don’t want to create a draft.

Sill Drilling

It’s easier to locate exterior walls, but before drilling, remember to take into account the width of the sill and the depth of the wall. In old buildings, the sills tend to be 6 to 8 inches wide, while the walls are typically 31/2 inches deep. So you have to drill at an angle through the sill to get inside the wall (Figure 5).

Figure 5. When an old sill is deeper than the wall, use a bit extender and drill at a shallow angle.

Often, the easiest way to figure the angle is to find a wire or pipe already drilled at the necessary angle and try to duplicate the angle. To further complicate the situation, many old foundations are made of stone. The stones protrude at irregular intervals, making it difficult to drill exactly where you wish. Also, many old foundations have been braced by having another foundation poured inside the old one; this makes the foundation even deeper and more impossible to drill. When faced with this situation, you may be able to drill up at the window wells (Figure 6).

Figure 6. For old foundation walls that have been reinforced with concrete, a window well sometimes provides enough room for drilling.