Everything You Need to Know About Hot Mopping

Lauren Murphy
Written by Lauren Murphy
Updated December 9, 2021
spacious grey/beige bathroom shower
Photo: Iriana Shiyan / Adobe Stock


  • Hot mopping is a waterproofing method that involves applying multiple layers of felt and hot asphalt to create a waterproof seal.

  • The hot mopping method is commonly used to waterproof bathrooms, specifically underneath showers, but you can also use it to waterproof your deck, roof, or other home projects, like planters.

  • Hot mopping is a messy and strenuous project with lots of room for error, so it’s best to hire an experienced pro to do the dirty work for you.

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While a bit of water on the bathroom floor may seem like no biggie, water leaks can lead to serious structural damage. Leaks also encourage mold and mildew growth, and in the long term, cause costly water damage that’s frustrating to fix.

Thankfully, you have some options to keep your home safe and dry. Hot mop waterproofing is a great solution to pesky leaks and something to consider when remodeling, especially in bathrooms where it truly shines.

What Is Hot Mopping?

While the name “hot mopping” sounds like a heavy-duty cleaning method, it’s actually a fairly messy process. It’s a waterproofing method, commonly used to waterproof bathroom floors, that involves heating asphalt in a kettle and applying it between layers of felt using a large mop, hence the name. The layers meld together while they dry to create an impermeable waterproof seal. 

This reliable waterproofing method seals off your shower and bathroom floor, preventing water from leaking onto the subfloor, ensuring there is no water damage to your home and none of the musty smells that come with it.

Where Should You Hot Mop?

While hot mopping is most commonly used to waterproof bathrooms, you can also use it to waterproof various home projects (think decks and indoor planters) as well as your roof. In fact, hot mopping is considered to be one of the best ways to cover and protect flat or low-slope roofs.

Still, the most common use for hot mops is under a shower pan. When you take a shower, most of the water runs down the drain (as it should). Inevitably, though, your tile and grout absorb some of it, sending it to the shower pan below your shower. The hot mop shower pan method creates a reliable waterproof seal under the shower pan to prevent moisture from trickling into your floors and causing damage.

Why Hot Mop Your Bathroom?

brown hardwood bathroom floor
Photo: Kristina Blokhin / Adobe Stock

Hot mopping is the optimal way to waterproof your bathroom floor. Hot mop pans work better and last longer than other bathroom floor waterproofing methods, including vinyl liners. Opting for hot mop installation during a remodel will give you peace of mind knowing that the risk of leakage and associated damages is virtually nonexistent. Hot mopping helps lower humidity levels inside your bathroom, too. The lower the humidity, the less likely water can infiltrate and damage your fixtures and appliances. Beyond that, hot mopping provides multiple layers of protection against all water leaks. 

Can You DIY Hot Mopping?

Hot mopping is a strenuous and dangerous project with plenty of room for error. The hot asphalt gets up to 400 degrees Fahrenheit, meaning you could seriously burn yourself if you make a mistake. The strong smell of asphalt isn’t fun, either. 

To get the best results possible, hire a professional shower installation contractor with hot mop experience to do the work for you. From start to finish, installing a hot mop shower pan will take a pro between one and two hours. Roofs may take a day or two to hot mop, and you should never attempt to go up on your roof, so definitely leave this one to a pro.

How Much Does Hot Mop Installation Cost?

HomeAdvisor reports that the cost to install a hot mop shower pan is between $250 and $400. The cost will vary depending on the size of your project (hot mopping a roof, for example, will generally cost more than hot mopping a small shower).

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