If you are installing heavy stone or tile or are a heavy-set person, you may wonder how much weight a shower base can hold. We have researched this for you and have found most shower bases can hold a significant amount of weight.
A cement or mortar shower base can easily hold upwards of 1,000 lbs, but the exact amount of weight a shower base can hold is dependent on a few factors:
- Residential floors built to code can support very heavy objects, but old or damaged subflooring may be weak.
- Cement and mortar vary in hardness and durability and are capable of handling very heavy loads.
- Tile and stone have different breaking points; some are lower than others.
- Shower kits, or trays, may provide a weight limit from the manufacturer.
To more accurately calculate how much weight a shower base can hold, you will have to consider the state of the bathroom floors, know which type of cement or mortar will be used, and look at manufacturers’ weight limits on construction materials if applicable. Please continue for more details on determining weight limits for your shower base.
Most Shower Bases Can Hold a Significant Amount of Weight
Shower bases are generally constructed of mortar and are therefore very durable and crack resistant. Mortar is a mix of cement, water, and other materials. It can be more sandy in texture (if mixed that way), is often water-resistant, and easy to work with.
Some construction materials or preexisting structural issues can weaken your shower floor and potentially damage your shower base. To create the strongest shower base possible, it’s best to familiarize yourself with these potential underlying issues as well as the construction materials commonly used to construct a shower base.
Floor Condition Has an Effect on Shower Base Weight Limit
According to the International Residential Code, residential bathroom floors should be built to hold a live load of 40 pounds per square foot --though aging or damaged floors may hold much less.
Bathrooms are notorious for developing water damage and wood rot due to the excessive moisture in the room. If built correctly, the base protects your floors from this moisture, but if built incorrectly, your floors may become weak and able to support much less weight. When installing a new shower base, check your support beams and subfloor for any water damage and verify the floor is built to code. A floor built to code can easily handle the weight of your average shower or bath.
Cement and Mortar Vary in Hardness and Durability
There are several different types of cement or mortar, each with its own strength and purpose. Portland cement is recommended for shower bases, but other mixtures can be used in conjunction or on their own to construct a shower base. Some of the mixes typically used to construct shower bases are listed below:
- Portland concrete is commonly used for shower bases and is very strong. It is water-resistant when dried and available in quick drying formulas.
- Thinset mortar is the best top layer for tile installation but is softer and more pliable and should not be used to construct the foundation layer of your shower base.
- Sand mix mortar is a sand cement mixture that is easy to trowel into a slope and can support a large amount of weight once dried.
Tile and Stone Have Unique Breaking Points
Each type of tile or stone has its own individual breaking point. There are ways to calculate this, as well as many general guidelines offered online. Ceramic subway tiles and porcelain are very common in shower floor construction.
Ceramic is very durable and has a breaking point of around 250-pound-force (lbf) though it is less impervious to the damaging effects of water than some tile. Water damage may cause ceramic to prematurely wear and eventually lower the weight limit for your shower floor.
Porcelain is very durable with a breaking point around 275 lbf and supports a large amount of weight. One of the most common shower floor tiles, porcelain, is nearly impervious to water and maintains its strength for many years.
- Granite is another very hard option, though much more expensive and known to be slippery when wet.
- Marble is beautiful but prone to scratches which can develop into micro-cracks, making it less durable over time.
- Limestone is also not a great pick to cover your shower base. It is soft and porous and weakens if not sealed properly.
Shower Kit Trays May Provide Manufacturer’s Guidelines
Shower kits with prefabricated tray inserts are made of synthetic, water-resistant materials; they are available at many major home improvement stores. Trays provide easy installation over a level subfloor; no cement or mortar is needed, except to adhere the product to the floor if needed.
Shower trays provide the required slope without manually troweling it yourself and are built to be reasonably strong base support for your shower floor. Shower kit trays and pans are very durable, but a mortar shower base is typically stronger.
The manufacturer may provide a weight limit or guideline for these shower kit trays, however, so make sure to read all installation and manual pamphlets they provide with your purchase.
Shower Base Construction Determines the Weight Limit
Proper construction and materials are key to building a strong and durable shower base. Some people confuse materials or construction methods, though it is important to know the ins and outs of a properly built shower base to make an educated decision on materials and project planning.
What is the difference between A Shower Pan and a Shower Base?
Firstly when familiarizing yourself with the construction materials used in and around a shower base, you must know that a shower base is different from a shower pan. A shower base is typically a hand-crafted, mortar subfloor for your shower. It is versatile and customizable in size and shape. This type of shower floor can generally support more weight than a prefabricated shower pan.
A prefabricated shower pan is typically formed from molded acrylic or fiberglass. It is often not necessary to construct a mortar shower base to support these shower floors. Though acrylic and fiberglass are super strong, a shower base made of cement or mortar is less likely to chip or crack.
For all the details, check out "12 Types of Shower Bases and Pans."
What Type of Shower Base is Best?
If you are looking for durability and strength, a cement or mortar shower base is best. Concrete mixtures have been used for ages to build strong, long-lasting shower bases. These materials are some of the strongest building materials in use and provide lasting support for your stone or tile shower floor.
Plan for your project, check out "What Are The Standard Sizes For Shower Pans/Bases?"
Is a Shower Base Better Than Tiles?
A cement or mortar shower base is not better than tile; it is for use with tile. A tile shower bed constructed over a regular plywood subfloor would not be water-resistant and is prone to shifting and cracking. When using tile or stone for your shower floor, it is important to add them only over a strong cement or mortar shower base.
Shower Bases Have Multiple Layers for Added Support
A shower base that is constructed properly has the best durability. There are several layers required to build a strong mortar shower base:
- A damage-free, up-to-code subfloor is the best surface to build a durable shower base on.
- The subfloor is then covered in a waterproofing barrier, typically a plastic membrane.
- Next, a base layer of cement or mortar is added as the main structural support for your shower bed.
- After the first layer of cement or mortar, builders may add a lath of expanded galvanized metal to help strengthen the top layer of mortar or other various structural and waterproofing additions.
- The top layer is constructed of cement or thin-set mortar at a slope of ¼ inch per foot, according to the international building code. The ¼ inch slope is needed to move water towards the drain, usually centered on the shower floor.
All of these layers are generally housed in some sort of wooden or metal frame, with shower curbs to prevent flooding, then covered with tile or stone.
How Much Does It Cost To Replace A Shower Base?
Building a strong shower base is not expensive. The shower floor that goes over the shower base is typically the largest expense when building a shower bed. Note, however, that tile and stone greatly range in price. Ceramic and porcelain are the most readily available and affordable tiles used in bathroom spaces. Granite and other luxury stone can cost thousands of dollars for an average-sized shower unit, but the actual shower base is always made of common inexpensive construction materials.
The cement or dry mortar needed to construct the base is reasonably priced and available at almost every home improvement store. This material may be found cheap at local hardware stores as well.
The waterproofing membrane needed is also easily obtainable for generally less than $50 to $100 for a roll. The size of the roll needed is determined by the square footage of the shower floor.
Often, the floor under your old shower base may be water damaged and in need of repair. This is an added expense that you should be prepared for when replacing your shower base.
Cement and Mortar Shower Bases Provide Solid Support
A well-constructed cement or mortar shower base can hold a large amount of weight. This type of shower base should be able to support any heavy stone or tiles you may choose and can easily support overweight people. Use stronger cement or dry mortar mixes and harder tile or stone for added durability.