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Dry-Fit Flange Spacer — Secure the Flange to the Subfloor

Intermediate

Part of project

How to Replace a Cast Iron Toilet Flange with PVC · Step 8 of 10

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In this video

Before applying any sealant, perform a dry fit of the toilet flange spacer. Place the spacer over the old flange and check its alignment. Confirm that the mounting holes on the spacer line up with solid parts of the subfloor where you can drive screws. Also, check the slots for the toilet bolts to ensure they will be positioned correctly for the toilet installation. This is the time to make any adjustments to the plan.

Goal: Confirm fit and alignment

  • If the mounting holes on the spacer don't align with a solid part of the old flange or subfloor, you may need to drill new pilot holes for your screws.

Used in this video

  • Toilet Flange Spacer (brand: Oatey, Material: Plastic, Size/Dimensions: 1/4 inch) — Raising the height of the toilet flange.
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FAQs

How difficult is replacing a cast iron toilet flange with PVC, and how long should I expect it to take?

This project is rated as intermediate. While it doesn't require specialized plumbing skills, removing the old cast iron and lead/oakum seal can be physically demanding and time-consuming. Expect it to take anywhere from half a day to a full day, especially if you encounter unexpected issues like a stubborn old flange.

What specialized tools are absolutely essential for removing the old cast iron flange and its lead/oakum seal?

Beyond basic household tools, you'll definitely need a cold chisel and a hammer for breaking up the old cast iron and carefully removing the lead/oakum seal. A shop vacuum is also crucial for quickly cleaning up debris and ensuring the cast iron pipe is spotless before installing the new flange.

What are the most important safety precautions I should take when demolishing the old cast iron flange and seal?

Always wear heavy-duty safety glasses to protect against flying fragments and a respirator (like the Honeywell R95) to avoid inhaling dust and potential lead particles from the old seal. Heavy-duty gloves are also essential to protect your hands from sharp edges and the demolition tools.

What's a common mistake when installing the new PVC compression flange, and how can I avoid it?

A common mistake is not thoroughly cleaning and deburring the inside of the cast iron pipe after removing the old flange. Any rough edges, rust, or debris can compromise the compression seal of the new PVC flange, leading to leaks. Ensure the pipe's interior is smooth and completely clean for a watertight fit.

Transcript
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cleaned all the wax off that area well I'm just gonna dry fit this get the screw holes lined up and the flanges where I want them so this has two ways you can use the set-in ones here they don't have as much adjustability or you can mine the slotted holes to the side you have more adjustability I'm not sure which way I want to do it but I'll figure out which way I want here in a minute get this dry fitted some probably put a couple screws in because I'm probably not gonna line up with the holes in this old flange perfectly which is fine my screws will be able to go through this ABS plastic into the sub floor but I will try to get them to where the old holes were I did there were three screws in this old flange that already removed they weren't even the right kind of screws they weren't galvanized or coated so they were all rusty but I'll get this dry fitted get a couple screws in see if it's going to be where I want it before I so kind of in dig a final install all right I got four screws in I'm

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