enter image description hereI'm trying to run a 3/4" conduit (1" OD) from unfinished basement utility room A to unfinished utility room B, through the ceiling of finished room C.

There are several floor trusses which are easy to bypass, but about 6 feet from the edge of the wall is a plywood firestop (red) that already has holes for Pex plumbing, black iron gas piping, and ventilation duct. From room A, I can get within about 4 feet of the firestop but I can't reach it to drill a hole.

I spoke with a contractor who said the easy method would be to cut a big piece out of the ceiling of room C, right next to the firestop (green) and then replace it when done - but I don't want to do this if I can avoid it since I won't be able to match the ceiling texture and paint afterward.

Will a flex drill bit extension (50" or so) allow me to drill the 1" hole I need? Is there another easy solution I'm missing that doesn't involve cutting a hole in the ceiling?

  • 2
    The flex fish bit is perfect for this. I just used one for a project.
    – Evil Elf
    Apr 16 '19 at 17:02
  • I would make a 1" drill 50" long - pipe and drill and welding...
    – Solar Mike
    Apr 16 '19 at 17:30
  • 2
    Awesome drawing! Made the question extremely clear. I'd go with a flex or rigid bit extension.
    – FreeMan
    Apr 16 '19 at 18:40
  • Whatever method you go with - put in 3 while you do it so you don't go through the same grief in a few years time...
    – Solar Mike
    Apr 16 '19 at 18:42

The flex auger bit is one good way to drill a hole several feet away.

Another option is a drill bit or hole saw extension. These might come in handy again in the future, whereas a 50 inch flex bit might not. The problem is that these extensions are offered only in short lengths (12-18 inch) so you'd have to stack several of them. That'll make it hard to aim, create some wobble as it spins, cost the same as the long flex bit, and if they work themselves loose there's a risk of the extensions separating as you try to pull them back after drilling the hole.

Extra points if you're using metal conduit and you form teeth in the end of the pipe to make a very deep hole saw/core drilling tool. ;-)

  • While I like the "toothed metal conduit" idea, I ended up using a flex auger bit and only had a little bit of trouble with the conduit couplers as they're larger diameter than the conduit and auger diameter. Apr 19 '19 at 15:52

When I come across problems like this I go in from the floor boards above. It can be the same amount of work but leaves the finish and colours of the existing ceiling as you mentioned wanting.

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