Solved! The Great Debate on Caulking Around the Toilet

Q: I am remodeling the bathrooms in my home and my understanding is that I should caulk around the toilet bases where they meet the floor. My neighbor says it isn’t necessary and might hide leaks. So, should I do it or not?

A: Judging by many of the conversations in DIY and plumbers’ forums online, you are not the only one who is confused. The debate over whether or not to caulk around toilet bases can even get quite heated at times.

Many people’s reasoning is based on tradition and personal opinion, which is fine but not a lot of help. Some have used ineffective fillers in the past that crumble away. They perhaps don’t understand the versatile and durable performance of modern caulking products. There’s also a need for clarification surrounding some of the problems that might occur, and how to solve them. We’ve looked into the pros and cons in detail to help people find the right answers.

The point of contention is leak detection. 

The main reason people give for not caulking around toilet bases is that they feel it could hide leaks. If left undiscovered, the resulting damage could become severe. Without caulk, the leaking water would flow out freely and be noticed right away, the theory goes.

While that might be true if there was a sudden and major breakage in a pipe, that’s rarely what happens. The vast majority of leaks are small and don’t spread out onto the bathroom floor, but instead soak into the underlying structure. They are usually noticed from the floor below the toilet when looking up. Leaks under the tub are often found in the same way. In apartments, it is common for the tenant below to be the one who first notices a problem.

So this argument for not caulking is somewhat flawed and as far as we know it is the only one. Lined up against it are a number of reasons why caulking around the toilet has positive benefits.

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Caulk prevents water from seeping under the toilet.

The same seal that supposedly prevents a leak from being discovered is actually beneficial in that it prevents “external” water from seeping under the toilet. Water splashed out of a shower or bathtub, for example, is unable to seep under the toilet if it is properly sealed to the floor.

If there is no caulk, any water that creeps underneath the toilet can remain undisturbed for some time. It will soon start to stagnate, providing a breeding ground for mold and fungus. The application of caulk to the toilet prevents this from happening, and the bathroom is healthier as a result.

Caulking around the toilet adds stability on uneven floors.

Bolts are usually used to secure the toilet base to the floor, but if the floor is uneven, the toilet can rock back and forth. This is frustrating, can be noisy, and is a potential source of trouble for the inner plumbing works. Tightening the bolts beyond a certain point  is a risky approach that threatens to crack the porcelain.

Sealing the toilet to the floor with caulk not only has the advantage of cleanliness, but can provide a layer of padding to compensate for that uneven floor. Once fully cured, good quality caulk offers effective and durable cushioning.

RELATED: Toilet Installation—DIY or Hire a Professional?

Plumbing codes require caulking a toilet to the floor.

This is arguably the single most important reason. In most parts of the United States, it is a requirement of building code to caulk around toilet bases. This could apply to both new builds and remodeling, though as regulations vary from one state to another it’s a good idea to check local statutes.

Professional plumbers generally have the required knowledge or will make inquiries for the client. For DIY installers it may be tempting to skip it. Unless inspection is necessary the homeowner may not consider it worth their time. Although there is potential for a fine, discovery is unlikely. However, if they subsequently wanted to sell the property, something found to be not up to current building code might put off potential buyers, or at the least make them more cautious in their appraisal of the property.

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It looks better and helps prevent unpleasant odors.

In many people’s view, a clean, white caulk line provides a neat, professional finish. It’s used around wash basins, showers and tubs, why not caulk around toilet bases? A dark, uneven join between toilet and floor looks unfinished by comparison.

There’s also the prevention of unpleasant odors that can sometimes emit from the plumbing and out under the bottom of the toilet. The problem will be made worse if mold or fungus forms under there.

Caulking the joint takes just a few minutes and has a wide range of benefits that surely far outweigh the unlikely event of a leak being discovered more quickly.