# How do I tap into a cast iron main drain line? **URL:** \ **Category:** Factual Questions\ **Created:** [September 2, 2002, 1:03pm UTC](https://boards.straightdope.com/t/how-do-i-tap-into-a-cast-iron-main-drain-line/126665 "2002-09-02T13:03:09Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [September 2, 2002, 1:03pm UTC](https://boards.straightdope.com/t/how-do-i-tap-into-a-cast-iron-main-drain-line/126665/1 "2002-09-02T13:03:09Z")
I first tried by calling 2 plumbers but thing are so busy they don’t want to do such a small and dirty job but my project must move on. I want to cut out a section to install a pvc tee in 2 places (probabally better to replace the big section then 2 little sections. I see it was done before up higher so I know it can be done (big rubber sleave over the cuts between the cast iron and the PVC). So 1 - How do I cut it? 2 - What are the chances my cutting will cause a crack in the wrong direction? 3 - Should I do something to support the weight of the section that will be suspended until the sleave inserted? THis is for a main drain stack where the top is throught the roof, then bathroom fixtures tie in, then kitchen, then into the slab where it has to turn towards the trap. ---
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [September 2, 2002, 1:14pm UTC](https://boards.straightdope.com/t/how-do-i-tap-into-a-cast-iron-main-drain-line/126665/2 "2002-09-02T13:14:43Z")
Here’s a [site](http://www.cispi.org/internet/cispi/chapter4b.htm) describing various cutting methods. The snap cutter (with the chain) is the one I’ve heard of before. It requires special tools and doesn’t look like an easy job. I would absolutely support both ends of the cut, this is very heavy pipe. I don’t have any real experience, so I don’t know how easy it is to screw up and damage the pipe. ---
**Author:** ![Billy\_Rubin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/billy_rubin/32/3622_2.png) [@Billy\_Rubin](https://boards.straightdope.com/u/Billy_Rubin)\ **Post date:** [September 2, 2002, 1:54pm UTC](https://boards.straightdope.com/t/how-do-i-tap-into-a-cast-iron-main-drain-line/126665/3 "2002-09-02T13:54:17Z")
You can buy a saddle. You use a hole saw and a big electric drill to cut a hole in the right position(harder than it sounds) and clamp on a saddle and a gasket. The saddle has either a tee or a wye junction, and is held in place with a couple of beefy clamps. It beats cutting the pipe out . If you have to cut the pipe, the snap cutter works really well, but if it’s old cast, as in 60-70 years old, it can be so brittle it shatters. A big sawzall works well for this, then you insert the new wye and clamp it in place with rubber boots and clamps. Good luck! b.