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Question on drilling holes for pipe

sunlight33 Member Posts: 378
What type of bits are preferred to drill holes for 3/4'' and 1'' copper pipe? It's all drywall for the interior walls, exterior wall has a layer of plywood.
Also do you use anchor or some sort to support the pipe in those holes?


  • BillyO
    BillyO Member Posts: 274
    I would probably use a paddle bit or hole saw
  • Jamie Hall
    Jamie Hall Member Posts: 19,425
    I use a quality paddle bit -- the sort with a pair of teeth on the edges of the paddle, which cut the paper surface of drywall. You need to cut about a quarter inch larger than the outside diameter of the pipe, and you do need to support the pipe -- otherwise you are just asking for odd noises as the pipe expands and contracts.

    Paddle bits work well in ordinary plywood and lumber as well.

    For larger holes -- such as might be needed for a faucet or a DWV line, for instance, I use a hole saw.

    A word of caution: the above comments are for drywall and plywood and ordinary modern lumber. If you ever encounter plaster on lathe, you are going to need a hole saw -- and be gentle. If you encounter older lumber -- say pre World War II -- never mind hardwood framing (it does exist!) -- you will need the best quality bits you can afford -- and expect to use them up (I learned that putting holes for wiring through some chestnut joists on a project...)
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 5,999
    An auger bit will work better in hardwood or old dense and dry softwood.

    Plaster or drywall will trash the bit, the spade bit can be sharpened and will cut well in wood again, the hole saw will be a bit more durable but would require a professional to sharpen if it even can be sharpened. Sometimes I will drill through the drywall or plaster with a masonry bit then switch to a wood bit to avoid dulling it.
    EBEBRATT-Ed Member Posts: 12,362
    @Jamie Hall

    Chestnut? That must be like drilling steel. I have run into that in old houses trying to staple romex. Bent staples don't work so well. Ended up with the wire tys with the mounting holes in them and drywall screws
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,787
    If you're going interior thru exterior, I'd use a long pilot bit to go straight thru. Then drill each end. I'm not really interested in poking a paddle bit thru insulation.
  • hot_rod
    hot_rod Member Posts: 16,875
    good point @STEVEusaPA about drilling from two directions.

    A holesaw would be the cleanest, although it will not be much good after a dozen or so holes :)
    How will you support the tube? Will it connect to something on both sides?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JUGHNE Member Posts: 9,908
    I use an 1/4" x 18" pilot bit to go thru both walls.
    I use a speed square placed on the wall and bit, on 2 planes to start the second hole, this insures that your bit is perpendicular to the wall.
    Drill thru insulation with the drill in reverse to keep from forming a cotton candy ball.
    Then complete with hole saw, again drill backwards for sheetrock to avoid tearing up the paper. (The hole saw lasts longer drilling backwards thru sheetrock, gives a cleaner cut than any other bit. )
    I usually would sleeve the copper with PVC, this lets the copper move without noise.
    So I use a hole saw to match the sleeve.
  • sunlight33
    sunlight33 Member Posts: 378
    I will use milford hanger to support the pipe to the ceiling stud.
  • sunlight33
    sunlight33 Member Posts: 378
    Is milford hanger the easiest/quickest way to support pipes hanging about 6 inches off the ceiling?