Solved! The Great Debate on Caulking Around the Toilet


The question of whether or not to caulk the base of a toilet to the floor can be a heated debate. We examine the pros and cons to find a definitive answer.

Question : I am renovating the bathrooms in my house and I understand that I need to caulk the toilet bases where they touch the floor. My neighbor says that it is not necessary and that it could hide leaks. So should I do it or not?

Answers: Judging by the many conversations in online DIY and plumber forums, you’re not alone in your confusion. The debate over whether or not to caulk the bottom of the toilet can even get heated at times.

Many people’s reasoning is based on tradition and personal opinion, which is fine but not very helpful. Some have used ineffective sealants in the past that crumble. They may not understand the versatile and durable performance of modern caulking products. It is also necessary to clarify some of the problems that can occur and how to solve them. We’ve examined the pros and cons in detail to help people find the right answers.

The point of contention is leakage detection.

The main reason people give for not caulking the base of the toilet is that they think it might hide leaks. If left undiscovered, the resulting damage can become severe. Without caulking, leaking water would flow freely and be noticed immediately, they say.

While this may be true in the case of a sudden, major pipe break, it is rarely the case. The vast majority of leaks are small and do not spread across the bathroom floor, but seep into the underlying structure. They are usually noticed by looking at the floor under the toilet. Leaks under the bathtub are often discovered in the same way. In apartments, it is common for the tenant below to be the first to notice a problem.

So this argument for not caulking is somewhat flawed and, as far as we know, the only one. On the other hand, there are a number of reasons why caulking around toilets has advantages.

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.

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.

It looks better and helps prevent unpleasant odors.
Many people agree that a clean, white caulk line gives a neat, professional finish. It’s used around sinks, showers and tubs, so why not caulk the base of the toilet? In comparison, a dark, uneven seal between the toilet and the floor looks unfinished.

There is also the prevention of unpleasant odors that can sometimes emerge from the plumbing and come out under the toilet base. The problem will be compounded if mold or mildew forms underneath.

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