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Install & Replace

Replacing ABS Pipe Connected to a Roof Drain

I live in a 2-story Condo with no attic access.  It has a flat-topped roof that has a drain.  The drain feeds the water out to the gutters on the side of my home. 


I recently had my roof replaced due to a roof leak in Room 1.  The roof replacement corrected the initial leak.


After the roof replacement was done I started experiencing a new leak in Room 2.  My roofer came back out over and over and could not find the root cause of this second leak.  Finally they cut through my ceiling in Room 2 and found that the drain in my ceiling was leaking.


There is a drain coming down through the roof into the attic.  It has a flex-pipe that attaches (via pipe clamps) to the drain to ABS pipe running parallel to my ceiling.  That feeds the water out to my gutters.  It looks like the flex-pipe was jostled loose and was no longer attached to the main drain fixture on the roof.


From what I see (as someone with some, but not much, plumbing experience), it would be better to replace the flex-pipe with solid ABS.  I do not know if this would be the best idea though.


Are there any benefits of using flex pipe over ABS that is cemented in?  Is there a detriment to using the solid ABS?  My theory is that I don't want the pipe clamps/straps to come off again and have the same situation.


It looks like I need about 4-5 feet of ABS, an elbow, a coupling, some pipe-cement, and some means of cutting the ABS.  I have only worked in excess with PVC pipe.  Is there an ABS primer that I will also need?  Many of the websites that I have read up on also recommend using just a regular saw to cut the ABS but stress the importance of cutting straight.  I vaguely remember a tool from my experiences in plumbing that is C shaped and spins around the ABS cutting it as you spin.  Is that an illusion or do such tools exist?


I guess the root of my question is this:  Is this something that I should tackle as a DIY project (note, I have very few tools) or should I just call a plumber?  I want to make sure this project gets done right the first time around.


Any input and suggestions are greatly appreciated.


Thank you,



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Posted 2012-12-07T21:52:35+0000  by tag078 tag078

I didn't realize I could post images, so here are some follow up images of my situation:


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photo 1.JPG

Posted 2012-12-07T22:05:01+0000  by tag078

Welcome !  Were glad you stopped by.


You have some good questions.  In my experience, the main reason someone would use a flex pipe is if it was too difficult to connect the traditional way (elbows not able to line up with the other pipe) - so check that first.


There is a specific cement for ABS pipe:  abs cement.jpg

I was not able to find a specific prime for ABS pipe, but I suspect that it may not be needed because the pipe is not under pressure.  Maybe one of our community members can "pipe" in on the matter.


You were also correct on the tool used to cut the pipe:   abs cutter.jpg

One other thing to consider; think about installing a clean out pipe to gain access if it should ever become clogged and you need to free it up.  Also, maybe an access panel to get to the pipe in the future. 


Posted 2012-12-09T18:05:18+0000  by Kevin_HD_ATL
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