3 Things To Consider Before Reinforcing Your Floor for a Bathtub
Written by Artisan Contracting on February 27, 2025
When it comes to bathroom renovations, installing a bathtub is a significant decision that can completely transform the space. While showers are convenient, a bathtub offers a unique level of comfort, allowing you to unwind after a long day.
Deciding whether to add a bathtub, and what type to choose, is just the beginning of the process. One crucial factor that often gets overlooked is whether or not your bathroom floor is reinforced enough to support the weight of your new tub. Here’s what you need to consider when reinforcing your floor for a bathtub.
1. Floor Reinforcement Budget
Before you get started with your floor reinforcement for a new bathtub, you must first weigh up the cost. This is an essential aspect of any bathroom renovation. For people who are fitting or re-furbishing their bathroom, there are a range of bathtub options available to them. A freestanding bathtub, for instance, may require more intensive floor support than a built-in tub because of its weight distribution.
Budget is key when considering reinforcement. The cost of reinforcing the floor will depend on:
● The materials you need
● The labor involved
● How extensive the modifications will be
For example, reinforcing the floor by adding extra joists will add to your overall expense, and hiring a contractor to ensure it’s done safely and effectively can also increase your costs.
If you have decided that you want to fit a bathtub, you then need to decide if you want a fitted tub, or a stand-alone. This decision will mainly depend on personal taste and budget.
2. Bathtub Weight
One of the most important factors to consider when reinforcing your floor for a bathtub is the weight of the tub itself.
Considering the Weight
The weight of a bathtub can vary greatly depending on the material they are made from. For example, a cast iron tub is significantly heavier than a modern acrylic tub.
You also have to consider the weight of the water, and of course the weight of a person. For older houses especially, this can be a concern.
Older Bathtubs vs Modern Bathtubs
Traditionally bathroom floors are built to withstand the pressure of an average bathtub, but as bathtubs have modernised, the weight has gotten heavier. The increased weight of larger or more solid tubs could pose a risk of sagging or even structural failure over time.
With all of this in mind, it’s crucial to ensure your floor can handle these stresses. If you’re unsure, a professional inspection of your floor structure may help you make an informed decision. Take a look at our blog on choosing the perfect bathtub for your bathroom renovation. This will help ensure you choose the right tub for your second floor renovation.
3. How to Reinforce Your Flooring
Plan Ahead
When you’re planning the reinforcement, it’s important to think about plumbing, as the pipes for your bathtub will likely need to run through the same space as the new joists.
Proper planning ensures that the plumbing doesn’t interfere with the structural reinforcement.
It’s also a good time to inspect your current joists for any signs of wear or rot. Water is always present in bathrooms, and over time, it can cause damage to the wood, weakening the floor structure. If you find any rotted joists, it’s best to replace them during the reinforcement process to avoid issues down the road.
Reinforcement Options
Sister Joists
There are several methods to reinforce the floor for a bathtub, with doubling the joists being one of the most common and effective.
This involves adding an additional joist parallel to the existing ones, which helps to evenly distribute the weight of the bathtub, water, and person using it. You can also consider installing larger or stronger joists if necessary. In addition, you may need to reinforce the subfloor itself, especially if it’s made from weaker materials like plywood.
Metal Reinforcement
As an alternative, some choose to install metal brackets or plates to provide support. This is a little more costly and sometimes not as effective.
Professional Help
For most modern homes, the existing bathroom floor will likely be strong enough to support a new bathtub, even a heavy cast-iron one. However, if your house is older or you’re noticing any signs of floor sagging or instability, it’s worth getting a professional contractor to inspect the area.
They can determine whether additional reinforcement is needed and provide guidance on the best approach to ensure your floor is up to the task.
If you’re looking for more information on renovating your bathroom, check out our guide to bathroom renovations.
For more information about reinforcing bathroom floors, get In Touch with Artisan Contracting today!
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