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Drain Pipe Repair and Flange Installation — Prepare Subfloor and Drain Pipe

Intermediate16 hours

Part of project

How to Install and Level a Shower Pan Base · Step 4 of 9

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In this video

Cut the old ABS drain pipe below the damaged area and prepare to install a new section. Use a pipe cutter for a clean cut. Cut a new piece of ABS pipe and attach a new coupling and toilet flange. Dry fit all the components first to ensure the final flange height will be flush with the finished floor. Use ABS cement to glue the coupling and new pipe section together, ensuring a strong, watertight bond.

Goal: Plumbing

  • Make sure you are using the correct glue for the correct pipe. Black ABS cement is for black ABS pipe, and clear or purple/blue PVC cement is for white PVC pipe.

Used in this video

  • Pipe Cutter (Tool Type: Plumbing Tools, Cutting_Tool: Tubing Cutter) — Cutting the ABS drain pipe cleanly.
  • Drill (Tool Type: Drill, Power Source: Cordless) — Driving screws to secure the toilet flange to the subfloor.
77.8K views74845-60 minutes
Oatey Co

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FAQs

How difficult is it to install a shower pan for a DIYer, and what's the realistic time commitment?

This is an intermediate project, requiring precision and patience, especially with leveling and mortar work. While the estimated time is 16 hours, allow extra time for potential subfloor repairs or unexpected issues. Rushing can lead to costly mistakes, so take your time and don't skip steps.

Why is a mortar bed crucial for a new acrylic/fiberglass shower pan, and which type should I use?

A mortar bed provides essential solid support beneath the shower pan, preventing flex, squeaks, and potential cracking over time. It also allows you to precisely level the pan for proper drainage. The project specifically calls for Type S mortar, such as Greencore or Quikrete mortar mix.

What are the most critical steps to ensure my shower pan is perfectly level and drains correctly?

Accurate leveling begins with a solid, level subfloor. Dry-fit the pan multiple times, marking its position and checking it with a long level in all directions. When setting the pan into the mortar, continuously check for level and adjust the mortar bed as needed before the mortar begins to set.

What precautions should I take to prevent leaks around the drain assembly and where the pan meets the wall?

Ensure the drain fitting is properly installed and sealed according to its manufacturer's instructions, using plumber's putty or silicone caulk as recommended. Secure the pan's flanges to the wall studs precisely, and apply a waterproof sealant where the pan meets the wall before installing wall coverings to prevent moisture intrusion.

Transcript
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So I didn't feel like I needed to clear out all of that second layer of subfloor from the entire room. Now I'm just clearing the pipe out of the way and replacing. I can't use that flange anymore, so I had to cut it down enough to where I can replace that ABS plastic pipe. I put a coupling on and a flange. Use this ODE ABS cement. Now make sure that you're using ABS, that's the black plastic glue for ABS pipe. Or if you're using PVC, use PVC glue. They are specific to that. And a transition glue that's supposed to be good for either one is not really that great of an option for either because it's just not. And actually it's not allowed by code. So I'm working this back together, I'm going to cut this piece to where it's just up to the subfloor levels, but I'm not going to glue the flange on just yet because I need to rework all of that subfloor on top of it. I'm just kind of fitting it here, making sure it's going to work. It looks good, so at this point, my pipe is okay, I keep putting these plastic bags in because I don't like getting sewer gas smell in my face. But now it's time to rebuild some of this wood. I had some leftover treated lumber from another project, so I was using that, but you could use regular 2x4s down below there or whatever. The goal here is I'm just trying to create something to secure this replacement piece too. So I'm attaching that to those joists, and that'll give me some structural support below this replaced subfloor. So I've got to cut my replacement piece. This is a half inch thick piece of wafer board, and you can see I didn't even measure. I just kind of lined it up with where that pipe is going to be, drill it out, make sure it fits. I had to take it back outside and trim it in a little bit just to make sure it would fit snug, but once it's down, it fit really nicely with that subfloor level that ply would be low. Now, I had to make sure that I was also using the correct width. So this structural subfloor was a little bit thinner than that subfloor that's up above it. So I ended up buying several different sheets to just try and get my levels the same for the next layer of flooring. So now I'm measuring that overall subfloor. I went out and cut it. I had to put a seam in right by the toilet there because I tried to get the whole sheet in at once. I ended up scratching the walls a little bit and you can see there's that water supply. I couldn't get it around that. So I cut the seam right where that toilet and that vent…

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