Fixing a Toilet Rough-In Mistake
Accidentally created a 14” rough-in for your toilet after removing plaster? Learn safe solutions without breaking the slab or risking clogs.
When renovating older bathrooms, it is common to uncover plumbing surprises. One challenge is creating an unexpected rough-in size. In this case, removing thick plaster left a 14” toilet rough-in. Unfortunately, 14” rough-in toilets are not always available locally, and ordering them can be unreliable.
Some homeowners consider creative fixes, such as using offset flanges or adapting pipe fittings. But which options are safe and code-compliant?
Question:
Can I use a reducing 4×3 Fernco donut inside a 4-inch ABS offset flange to connect to a 3-inch cast sewer pipe for a 14” rough-in?
Answer:
No. This is not recommended. Offset flanges and donuts may not align properly with cast iron pipe, leading to clogs or weak seals. A better solution is to use a toilet with a standard 12” rough-in and add a spacer or deeper tank to cover the gap. Another option is ordering a 14” rough-in model from a reputable supplier. Breaking concrete should be the last resort, but unsafe fittings should also be avoided.
Offset flanges exist, but they are designed for specific situations and do not always work with cast sewer pipe. A loose or incorrect fit could result in sewer gas leaks or frequent blockages.
For guidance, check this Handyman guide on toilet flange repairs. You can also explore Home Depot’s toilet installation guide.
Whenever possible, stick with fittings that are made for your pipe size and material. It may take patience to find the right toilet or part, but it will save you headaches later.
I’m Chris Mayer, writing for Plumbing 101.
