If you are planning a bathroom remodel in Raleigh, Cary, or Durham, you have likely heard the term "waterproofing" mentioned as a critical line item. However, not all waterproofing is created equal. In the high-humidity environment of North Carolina, the method used behind your tile is the single most important factor in whether your shower lasts 30 years or fails in five.
At The Jevn Group, we utilize the Schluter-KERDI system. Here is a technical breakdown of why this system is the industry benchmark and why we consider it essential for every Raleigh bathroom.
The Problem with "Old School" Shower Construction
For decades, the standard way to build a shower was the "water-managed" method. This involved:
- Cement Board: A substrate that, while it won't rot, is actually porous. Water passes right through it.
- Vapor Barrier: A plastic sheet stapled behind the cement board to prevent the wood studs from rotting.
- Rubber Liner: A "pan" at the bottom designed to catch water that has already leaked through the tile and mud bed.
The flaw in this system is that the entire assembly—the tile, the grout, and the mud bed—stays wet. This "wet sandwich" is a breeding ground for mold and efflorescence, especially in Raleigh's humid summers where evaporation is slow. According to the TCNA (Tile Council of North America) Handbook, water-managed systems are increasingly prone to failure in modern "steam-heavy" residential showers (TCNA, 2025).
What Is Schluter-KERDI?
Schluter-KERDI is a "bonded" waterproofing system. It is a pliable, sheet-applied polyethylene membrane with a non-woven fleece on both sides to anchor it in thin-set mortar.
Unlike the old method, KERDI is applied on top of the substrate (the walls and the floor) but directly behind the tile. This means the water never even reaches the wallboard or the floor mortar.
Why Raleigh Homeowners Need This System
1. Vapor Management and Humidity
North Carolina has an average annual relative humidity of roughly 70%. In a bathroom, this can skyrocket during use. The KERDI membrane has a very low water vapor permeance (0.90 perms when tested according to ASTM E96). This prevents moisture from migrating into the wall cavity where it can cause hidden "black mold" and structural rot.
2. The Integrated Drain System
A common point of failure in showers is the connection between the waterproofing and the drain. The Schluter-KERDI-DRAIN features a large integrated bonding flange that provides a massive contact area for the membrane. This creates a permanent, watertight seal that traditional "clamping ring" drains cannot match.
3. Crack Isolation
North Carolina clay soils are notorious for expansion and contraction, which leads to foundation settling. This movement often causes tile and grout to crack. Schluter membranes provide "uncoupling" properties, meaning they allow for a small amount of movement in the substrate without transferring those stresses to the tile.
The Cost vs. Value of KERDI
Installing a Schluter-KERDI system typically adds a modest amount to the initial material cost of a bathroom remodel. However, when compared to the cost of a "rip-and-replace" job due to a leaking pan or moldy walls, the value is clear.
Industry benchmarks from the 2025 Tile Industry Report show that moisture-related failures account for over 80% of residential tile litigation (National Tile Contractors Association, 2025). By using a certified, bonded system, you eliminate that risk entirely.
Our Standard: No Exceptions
We don't offer Schluter-KERDI as an "upgrade." We install it on every shower project because it exceeds Wake County and Durham County building codes and aligns with our commitment to the Triangle Standard. We believe you should only have to build your shower once.
Building a new shower in Cary or Apex? Learn more about our technical standards for bathroom remodeling.