Why We Set Tubs and Shower Pans in a Mortar Bed (And Why It Matters)

If you are planning to replace a bathtub or install a new shower pan in your Minnesota home, there is one critical detail that can make or break the quality of the job: setting the base in a mortar bed.

At Predictable Plumbing, we take pride in doing things the right way. That means going beyond the bare minimum and ensuring your tub or shower is fully supported, quiet underfoot, and built to last.

In this post, we will explain what a mortar bed is, why it matters, and how it protects your investment long term.

What Is a Mortar Bed?

A mortar bed is a layer of mixed cement that is spread under a bathtub or shower pan during installation. Once the tub or pan is placed on top, the mortar hardens and fills any gaps between the base and the subfloor.

This step ensures even weight distribution and a solid, stable foundation.

Why Is a Mortar Bed So Important?

1. Prevents Cracking and Flexing

When tubs or pans are installed without full support, they can flex or move slightly when someone steps in. Over time, this movement weakens the structure and may lead to cracks, leaks, or even failure of the fixture.

2. Protects Against Leaks

Unsupported tubs often shift slightly under use. Even minor movement can compromise the seal around the drain or the wall connections. A solid mortar base helps keep everything in place and leak-free.

3. Reduces Noise

Ever step into a tub that creaks or squeaks under your weight? That is usually because it was not set in mortar. A properly supported fixture is quiet, stable, and feels solid beneath your feet.

4. Handles Uneven or Concrete Subfloors

In many Minnesota homes—especially in basements or older properties—subfloors may be uneven or poured concrete. A mortar bed fills those imperfections and creates a level surface, ensuring proper drainage and long-term performance.

Why Some Contractors Skip This Step

Unfortunately, some installers cut corners by using foam pads or setting the base directly on the floor. While it saves time, it often leads to premature failure of the tub or shower base.

At Predictable Plumbing, we do not take shortcuts. We know that using a mortar bed is the right way to support your investment and avoid callbacks or costly repairs down the road.

Is a Mortar Bed Required by Code?

While not always technically required by plumbing code, most manufacturers recommend or require a mortar bed to keep the product under warranty. Skipping this step can void coverage if problems develop.

We follow both code and best practices—so you get a result that is both compliant and long-lasting.

Planning a Shower or Tub Replacement?

Whether you are remodeling your bathroom or replacing a worn-out fixture, we can help you get it done right. We install shower pans and bathtubs with full mortar support, level placement, and code-compliant plumbing connections.

We also offer:

• Mixing valve replacements

• New drain installations

• Professional fixture upgrades

Serving Homeowners in [Your Service Area]

Predictable Plumbing provides professional plumbing services to homeowners in Minneapolis, the western suburbs, and surrounding areas. Our work is clean, to code, and designed to last—not just pass inspection.

If you are planning a bathroom upgrade or just want a second opinion before hiring someone, we are happy to help.

Contact us today for an estimate or to learn more about our process.