Cutting Holes in Sheetrock For Electrical Boxes

[Dennis McDonaugh]

I'm going to put sheetrock up on the ceiling of my workshop this fall and I have plastic electrical boxes on the ceiling. Can I cut out the holes with a rotozip after placing the panels against the ceiling, or do I need to precut the holes?

[James Tibbetts]

I would say pre-cut them. No dust in the face. I've never used a Roto. Do the bits have a pilot bearing to follow the outside of the boxes? Is the diameter of the bit small enough to make a hole that a cover plate still hides?

[Dennis McDonaugh]

I would say pre-cut them. No dust in the face. I've never used a Roto. Do the bits have a pilot bearing to follow the outside of the boxes? Is the diameter of the bit small enough to make a hole that a cover plate still hides?

The bit is pretty small because the hole fits the metal box pretty snugly. There isn't a pilot bearing, but its not a real aggressive cut and the box is metal so the sheetrock cuts a lot easier and you don't have to worry about damaging the box. I've never seen it used on plastic though.

[Mike Ontko]

I've used a RotoZip to cut out wall outlets around plastic boxes, and it's possible but because plastic is a softer material, the "feel" for the edges of the box is entirely different than it is for metal. I would recommend practicing a little using scrap pieces of drywall with a plastic box mounted behind, just to get a feel for the touch and sound response of the tool.

[Steve Peterson]

I have a rotozip, but still precut the holes. I find it easier than doing it in the air, although a rotozip might result in tighter holes. The bits are 1/8" diameter. They only cut on the middle of the bit. The end 1/4" is smooth and acts as a bearing surface.

Steve

[David Helm]

Generally the pros use a roto zip or some other tool that is similar. The concept is that it is much faster to do it that way.

[Dennis McDonaugh]

Thanks for the input. I think I'll give it a try.

[Tom M King]

For I don't remember how many years, I've been using old work boxes exclusively. Wires get just a staple at rough-in. Mount box in sheetrock, and feed wires in the box as you mount the panel. My Inspectors have all liked the idea so far. This way, there is not only no extra space around the box, or worry about where it is behind the piece you're putting up. Another big advantage is you can pull devices up tight to the finish wall, with no sliding around of switches or receptacles after they're installed since the box finishes at the perfect height relative to the finish wall. I keep templates for rectangle boxes and round ceiling boxes (which require a bit of a weird cutout if you fit them tightly). A bead of construction adhesive around the back of the box, after you pull the "ears" up, seals the opening around the outside, and fire caulking around the wires coming into the boxes after it's up seals the whole thing. It's really not much trouble once you do it a few times, and less is you are also the sheetrock finisher. Another advantage is you have some more latitude for box location. If it's a weight bearing box, like for a ceiling fan, a piece of 2x at the right height above the box thickness lets you mount it plenty strong.

I do the same thing with almost any finish wall, from sheetrock, to T&G boards, to whatever.

[Joseph Montroy]

Tom that is a GREAT idea...wish you had said that 6 months ago, before I hung 62 sheets...Oh well

[roger wiegand]

My rotozip bits for this purpose have a pilot-- the last half inch or so has no cutter groove. Works fine on plastic boxes, with no danger of chewing them up. (That said, I really don't like plastic boxes and never use them, seems the screw holes that hold the outlets/switches will strip out as often as tighten down.) There are many different rotozip bits available.

I've hung boxes unattached in drywall before using old work boxes, seems like sooner or later you bump it or give it an overenthusiastic push with a tight plug and you shove the box back into the wall. I'll stick with metal firmly attached to a piece of solid wood, thanks.

[Jim Dwight]

I bought the rotozip bits and tried them in an old J. C. Penney router (a junk router, in other words). I didn't like it. Not terribly difficult to control but not really easy either. The "professionals" that used this technique on my recent addition also left gaps that the cover plate didn't cover at several spots. It takes an additional minute or two but I cut the hole before I put the sheet up. I like to use my HF vibratory saw to cut the hole. Much easier than using a knife. If you're worried about your measurements (and I have cause to be worried) you can cut a smaller hole and then enlarge after the sheet is secure. On my workshop, the walls are OSB and I cut the rough hole with a jig saw and trim with the vibratory saw if necessary. I don't deliberately make it too small but I don't cut it oversize either so if I miss a little, I can usually trim a little and the cover will still cover my mess. I skim the OSB with drywall compound and that also helps with gaps.

[Tom M King]

Here are the boxes I use: http://www.homedepot.com/p/Carlon-1-...118R/100154882 I cut a piece of plywood the right size to mark the hole by. Cut the face paper and maybe half way through with a sharp utility knife. Regular sheetrock jab saws have too big teeth to suit me, so I glued a Bosch jigsaw blade in a wooden handle. It gets pushed through the corners and cuts the rest of the box out. It's probably been used for 20 houses, and I've not had to replace it yet. A clean fairly tight hole is easy to do like this. The bead of construction adhesive must help the strength as well as seal the opening. I've never had anyone damage one in any house I've sold. Those boxes have some sort of fiber reinforcement, strong ears, and I've never had a hole stripped in one either. I use them for regular light fixtures too.

The built in wire "clamps" are a bit of a pain, so I twist them off and out of the way which leaves a hole not too big, but big enough to easily get wires in without having to aggravate them into the box while wrestling the sheet on the wall. Fireproof caulking seals the wire entry holes-which are the only holes in those boxes, so it leaves the finish wall sealed as well.

I always felt like oversized cover plates showed shoddy work, and that was my first reason for doing boxes this way. I hate oversized covers, and this method allows you to use a standard sized cover plate with no extra wall finishing to do. It's also nice that the device can't be slid around on the wall.

[Frank Pratt]

My rotozip bits for this purpose have a pilot-- the last half inch or so has no cutter groove. Works fine on plastic boxes, with no danger of chewing them up. (That said, I really don't like plastic boxes and never use them, seems the screw holes that hold the outlets/switches will strip out as often as tighten down.) There are many different rotozip bits available.

I've hung boxes unattached in drywall before using old work boxes, seems like sooner or later you bump it or give it an overenthusiastic push with a tight plug and you shove the box back into the wall. I'll stick with metal firmly attached to a piece of solid wood, thanks.

X2. I hate plastic boxes too. I've been an electrician for almost 40 years & have had lots of experience with both. Rework boxes will work, but at the expense of time & quality.

After cutting 2 or 3 holes with the RotoZip it gets pretty easy. My shop walls are 25/32" OSB & I used a RotoZip for all the outlet boxes. It was slow, but it did a great job.

[Scott T Smith]

I love my Rotozip for electrical box cutouts in drywall. Fast, easy and accurate. Ditto the previous comments about buying bits that have the smooth end for guiding around the box.

[Julie Moriarty]

Few drywallers I've worked with ever pre-cut openings. Before the Rotozip, they used a router with the base removed. It's messy but fast. Drywallers never seemed to care about the mess. Speed prevailed. And if there is a door opening, they lay the drywall over it and cut the opening, after the drywall is screwed in place, with a drywall saw.