Retrofitting in Insulated Walls
Author: Grayson Evans, Training Dept. Seminars – Copyright 2008
Drilling up or down, or fishing cable in insulated walls is an inconvenience but nothing more. Sure, there are certain techniques you can’t use through insulation like dropping a ball chain (actually, you can use a ball-chain, read on) but there are always workarounds.
Measure how much you need to feed the rod up/down the wall so that the chain will be located to the left or right of the opening you made in the sheetrock. Feed the rod down the corner. Now you can use a magnetic retriever tool going in sideways from the hole to where the chain will be located.
At every retrofit class I hold and at retrofit demonstrations in our booth at shows, I ALWAYS hear “…yea, but you couldn’t do that in an insulated wall.” Guys relatively new to retrofit, and even some seasoned pro’s seem to have a real fear of insulated walls. Fear not!
Drilling up or down, or fishing cable in insulated walls is an inconvenience but nothing more. Sure, there are certain techniques you can’t use through insulation like dropping a ball chain (actually, you can use a ball-chain, read on) but there are always workarounds.
I’m assuming by “insulated walls” most people mean wall cavities with fiberglass batt insulation. This stuff was used in nearly all homes starting in the early 1960’s, usually in outside walls or in walls that divided “conditioned space” from unconditioned space. This type of insulation is almost always associated with sheetrock as the wall covering.
Older homes either have no insulation or someone has retrofitted in something like blown-in fiber. This stuff is no problem, it just makes a mess when you make a decent size opening in the wall. It has usually all settled to the bottom of the wall anyway. Some newer homes have expanded foam in the walls. Not impossible to deal with, but difficult (and the subject of another TIP).
Therefore I’ll deal with techniques to work around fiberglass batt.
I’ll discuss dealing with insulation in two categories: drilling and fishing
Drilling in Insulated Walls
Regardless if you’re drilling up/down in an insulated wall from an opening in the wall, or into the wall cavity from above (through top plate) or from below (through sole plate), the place you want to be with the drill bit is in the corner of the wall cavity.
If you’re drilling up from an opening you’ve made for an outlet or speaker in the sheetrock, then push the bit through the insulation, using short jabs, at an angle up and toward either back corner. If there is paper/foil/plastic on your side, just cut through it. When the bit hits the back corner, walk the bit into and up the corner by giving the drill short bursts (forward or reverse, whichever works better). If you can keep the drill in the corner, you’ll have no trouble with the insulation. I demonstrate this several times in our “Residential Retrofit Installation” video (www.trainingdept.com/html/videos.html)
If you’re drilling down into a basement or crawl space from an outlet opening that is near the floor use your drill guide to keep the bit in front of the insulation and aim the bit into one of the front corners.
If your drilling into the wall cavity from above or below, try to make the hole so it’s near one of the corners. Sometimes the best corner to use depends on how the insulation was installed. If there is no foil or paper backing, it doesn’t matter much. If the insulation has a foil or paper backing, then it may have been installed by stapling the paper/foil to the inside of the studs (like the top example in the diagram above). This creates a nice open space on either stud near the sheetrock. Try to make your hole here (use a spring steel “feeler bit” to locate the exact spot). If the insulation was stapled to the outside of the studs, then there is usually a nice open space in the center of the wall cavity. This make fishing the cable up/down much easier.
Fishing Cable in Insulated Walls
Once you have the holes drilled, fishing is actually easy. There are a couple of ways to do it.
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Technique #1
If you are fishing the cable up/down from an opening in the sheetrock, then you want to follow the same path you made when you drilled the hole. Use a fiberglass rod with a bullnose end. If you’re fishing a small cable (security cable) you can attach the cable to the end of the rod by threading one of the wires in the cable through the hole in the bullnose. If you need to fish a larger cable or bundle, or if your buddy is going to feed the cable to you from above or below, then thread a pull cord through the bullnose.
Push the rod to the same corner you used with the drill bit. The rod will follow the corner and pass up/down through the hole the bit made. Your buddy attaches the cable to the pull-cord and you pull it back down with the cable.
If you are feeding the cable up or down into the wall cavity from an attic or crawl space, then attach the cable to a fiberglass rod and get the rod into a corner, preferably a corner on the same side as the opening you’re trying to fish the cable to. Again, this can be made easier by fishing down a pull cord and then retrieving the cord out the opening, attach the cable to the pull cord in the attic/crawl space, and pull the cable out with the cord. That is always easier than trying to wrestle the rod through the insulation.
Technique #2
There is another technique I like to use by attaching a ball-chain to the end of a rod using a screw-on attachment. You can use several feet of ball-chain to do this.
Measure how much you need to feed the rod up/down the wall so that the chain will be located to the left or right of the opening you made in the sheetrock. Feed the rod down the corner. Now you can use a magnetic retriever tool going in sideways from the hole to where the chain will be located. If you feel around, you’ll “hit it”. Slowly pull the retriever out with the chain attached. The figure below shows how the rod with chain is positioned. Keep the magnetic retriever against the inside of the sheetrock.
Technique #3
There’s another interesting way to fish a cable into the cavity from above/below that involves using strong magnets. BES Manufacturing’s “Wire Python” is a good example. The tool consists of two parts, a “paddle” magnet, and a “wire leader” magnet. These magnets are so strong that they will easily grab each other and not let go through ½” sheetrock (or probably thicker). You attach the cable you want to pull on the “wire leader”. This has a hook for the wire with a strong magnet attached. You can push the wire leader with the cable attached toward the sheetrock (or the side with the opening). Hold the paddle magnet against the wall and move it around a little till it “latches on” to the leader magnet. Then using short pulling motions, you can pull the leader magnet right through the insulation to the opening.
This is much easier to understand once you see it. A short quicktime movie is at:
www.trainingdept.com/video/WP_fishing.mov (It takes a Quicktime plug-in)
The video shows how to feed the cable down the wall, grab it and pull it to an opening. The video also shows how to retrieve a ball chain on the end of a rod quickly through insulation. Again, this presumes that the opening is in a corner.
If you have any questions about anything in this TIP or a related retrofit tip, drop me an e-mail at grayson@trainingdept.com I will actually answer it!