Replies

1. 
   calvin | Jul 23, 2014 04:13pm | #1

   Mike

   You'll have figure whether a waste or vent.  2 story and you're on the first- probably

   waste.  If you be on the second, might be a vent from down below.

   one way to check, screwdriver stethoscope .......run water from above, hold blade end of driver to pipe....butt end, cup in fist and hold to your ear.   Hear anything?

   blocking?   Hog/ dado out the backside of whatever your using or notch it at each pipe if 2 x on edge.

   figure where you want the fasteners an put painters tape at the pipes after you cover it up.   Now, make damn sure you use the proper length screws when mounting ( in that pipe area ) .

2. 
   DanH | Jul 23, 2014 07:59pm | #2

   Get a coupler the same diameter as the pipe.  Saw it in half lengthwise.  somehow hog out the center divider of one half so you have essentially a smooth piece of "half pipe".  (Or perhaps just saw off one end, since you don't need the full length.)  Glue this piece over the cut with regular ABS glue, then fasten with a spiral hose clamp.

   If you look around you may find a different fitting that will work better than the coupler.

1. 
   gfretwell | Jul 24, 2014 01:17am | #3

   Repair coupling

   DanH wrote:

   Get a coupler the same diameter as the pipe.  Saw it in half lengthwise.  somehow hog out the center divider of one half so you have essentially a smooth piece of "half pipe".  (Or perhaps just saw off one end, since you don't need the full length.)  Glue this piece over the cut with regular ABS glue, then fasten with a spiral hose clamp.

   If you look around you may find a different fitting that will work better than the coupler.

   Use a "repair" coupling, it does not have the rib in it and glue it in (slide it up, glue liberally, slide it down glue liberraly and center it)

   Plan B use a hubless Fernco.

1. 
   DanH | Jul 24, 2014 07:53am | #5

   I've never seen repair couplings for plastic, though I suppose the specialty houses have them.  The point of my scheme is that you don't have to cut the pipe through or work a repair coupling over the pipe.  And a Fernco would probably be too large to readily fit into the wall, since the pipe is inevitably not centered in the cavity.

   Granted, an inspector might wince at the repair, but practically speaking it's less likely to leak than the cut-the-pipe-and-slide-on-repair-coupling approach.

3. 
   user-1116010 | Jul 24, 2014 05:58am | #4

   scoring with a knife will prevent........

   Dyna,

             We make a lot of drywall penetrations, and to prevent plunge cut mishaps, we always use a sheetrock knife. Multiple passes with the knife are required, and it is a little slower, but the results are consistent - a cleaner opening, less dust, and the chances of cutting into something other than the drywall are greatly reduced. 

             When opening a wall to install blocking, we usually make a larger hole, and use plywood as the first layer, and, depending on the circustances, we will install it flush with the face of the studs, or install it in place of the sheet rock; it can be skim coated and finished to match the existing wall board. Where necessary, additional wood can be fastened behind the plywood, in the pockets between wires, piping, etc.

              We have used mission couplings, fernco couplings, and, 1/2 of a " slip " coupling and ss clamp to repair the accidental cut you've described, and sometimes there can be enough " play " in the damaged pipe to install  a regular coupling.............

             

1. 
   DanH | Jul 24, 2014 07:56am | #6

   I've found that a Mulltimaster cuts the drywall with reasonable speed while allowing you to easily control penetration depth.  Or, as you say, use a utility knife.

1. 
   user-1116010 | Jul 24, 2014 08:08am | #7

   multi tasking

   Dan,

           Yes, the multi master is a fein tool for these applications, and, if you have an extra pair of hands to trail, or lead with the business end of a vacuum hose, dust can be kept to a minimum........