Purple Board vs Plywood? Which is Better for Bath or Shower Wall Installation?

You’ve made the decision, you’re finally remodeling your bath or shower! You’re looking forward to creating a space that feels fresh, modern, and relaxing. But while the look of your new bathroom is important, what’s behind the walls matters just as much—if not more.

The materials used to support your bath or shower walls can make a huge difference in how well your remodel holds up over time. The choice between Purple Board and plywood will not be something you see, but it plays a critical role in preventing moisture damage and ensuring your investment lasts for years to come. 

At Joyce Windows, Sunrooms & Baths, we’ve helped over 20,000 customers remodel their homes with exceptional-quality solutions. We understand that your home is your most significant investment, and choosing the right materials can be daunting. Our experts can help you evaluate your current bath or shower and explain why our bath replacement installation materials are best for your home.

Choosing the wrong backing material for your shower can lead to costly repairs and even health concerns due to water damage and mold growth. Why does Joyce use and recommend the Purple Board? Let’s break it down.

What is Purple Board?

PURPLE Board is a moisture and mold-resistant drywall designed for use in high-humidity areas like bathrooms and kitchens. Unlike standard drywall, it has a special coating that helps prevent water damage, making it a better choice for areas exposed to moisture. While it’s similar to green board, which is also moisture-resistant, purple board offers enhanced mold and mildew protection. 

In 2003, Gold Bond introduced the first PURPLE XP® drywall, which offered extra protection by combining traditional moisture resistance with added mold and mildew defense. This breakthrough came after the company’s research team discovered a special ingredient developed by a chemical company.

Created initially as a food preservative, this antimicrobial formula, called SPORGARD®, was designed to prevent food from spoiling due to mold and other microorganisms. Through careful testing, Gold Bond realized that the same technology could be used to protect drywall from mold growth.

By adding SPORGARD to drywall, it quickly became a game-changer in the building industry. It offers a cost-effective and mold-resistant solution for interior construction projects. Other drywall companies have since adopted this formula to provide this option to consumers and beyond.

Pro Tip: When it comes to bathroom and shower wall installations, “Purple Board” gets thrown around a lot, like how people say “Kleenex” when they mean any tissue. But here’s the thing: not all moisture and mold-resistant drywall is actually purple. The color can vary by brand, but the performance is what really matters.

What is Plywood?

While most people don't think about how plywood is made, it is made by gluing together multiple thin layers (plies) of wood veneer. These layers are arranged with their wood grains alternating at 90-degree angles, giving plywood durability and resistance to warping or splitting.

After trees have been logged, cut (like a paper towel roll), and dried, the veneers are stacked with the wood grain alternating in different directions, then glued together using strong adhesives. After stacking, the veneers are pressed under heat and pressure to bond them into a solid sheet. Finally, the plywood is trimmed, sanded, and sometimes treated for extra durability.

Purple Board vs. Plywood in Bath or Shower Installation

The hidden materials provide the foundation for your shower or bath. While choosing between moisture and mold-resistant drywall board and plywood might not seem important at first, it can make all the difference in durability, moisture protection, and long-term performance.

Moisture & Mold Resistance: Protecting Your Investment

Bathrooms are naturally humid spaces, making moisture control a top priority. Purple Board is specifically designed to resist water, mold, and mildew, preventing hidden damage that can lead to costly repairs. Plywood, on the other hand, absorbs moisture over time, which can cause it to warp, rot, and even grow mold behind your walls. Even if plywood is sealed, it still carries a higher risk of moisture-related issues compared to Purple Board. Choosing the right material from the start helps protect your bathroom from hidden water damage that could weaken your entire remodel.

Building Codes & Industry Standards: What the Pros Recommend

When it comes to bath and shower installations, many building codes and professionals recommend moisture-resistant drywall like Purple Board for walls in wet areas. This is because it meets industry standards for mold resistance and structural integrity in high-humidity environments. Plywood, even when treated with moisture-resistant chemicals, is still vulnerable in high-moisture environments like bathrooms and showers. Over time, constant exposure to humidity and water can cause the layers of plywood to swell, warp, or delaminate. More importantly, once moisture seeps in, it creates the perfect breeding ground for mold and mildew, which can compromise both the structure and health of your space. By using moisture- and mold-resistant drywall board, you’re choosing a proven solution that ensures your bathroom meets safety and durability standards from the start.

Purple Board:  The Smart Choice for Lasting Protection

While both materials have their place in construction, Purple Board or moisture and mold-resistant drywall is the clear winner for bathroom walls. Its moisture resistance and compliance with industry standards make it the best choice for a long-lasting, worry-free remodel. When investing in a new bath or shower, don’t overlook the importance of what’s behind the walls—because what you can’t see could make all the difference.

When it comes to choosing the best materials, Joyce Windows, Sunrooms & Baths doesn’t settle for anything less than the best for our customers. That’s why we only use moisture and mold-resistant drywall in every bath and shower installation. We want to ensure that your new space is not only stunning the day it’s installed but also built to last, offering you peace of mind for years to come.

Let us help you create a bathroom that is not only beautiful but also protected from moisture's hidden dangers. Schedule your free quote today with one of our bath experts.