One of the Biggest Waterproofing Mistakes We See On Our Shows

If you’ve watched my shows, you know how many surprises we uncover behind the walls. One of the biggest waterproofing mistakes we see on our shows is partial waterproofing. It’s shocking how often we open up a bathroom or shower and find that only some areas were protected.

Waterproofing isn’t something you do halfway. Every vulnerable area must be sealed and protected. Cut corners, and you’re asking for leaks, rot, and mold down the road.

Here are the areas where proper waterproofing is absolutely critical:

 

Waterproofing Around the Curb

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The shower curb is one of the biggest failure points. This area takes constant abuse from splashing water and runoff. If it’s not fully wrapped and sealed — including the top, inside face, outside edge, and connections to the floor — water will find its way through. A failed curb is one of the most common causes of leaks into adjoining rooms or below the bathroom.

 

This is why we use the Schluter ® -KERDI-BOARD curb on our jobs. It’s lightweight, waterproof right out of the box, and works perfectly with the whole Schluter ® -Shower System. Instead of building a curb on-site — and risking mistakes — this gives you a solid, tile-ready base from the start.

 

Set it in with thin-set, seal it with KERDI-BAND, and you’ve got a fully waterproof curb. No guesswork, no extra steps — just a proper install that keeps water where it belongs.

 

RELATED: 7 Reasons to Install a Shower Knee Wall

Waterproofing Around Pipes & Penetrations

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Any spot where a pipe comes through the wall or floor is a weak point for a potential leak. That means hot and cold water lines, tub taps, mixing valves, shower heads and drains. Without proper seals, gaskets, and waterproofing membranes, moisture will seep behind the tile and into the structure. Always use approved waterproof pipe seals and ensure the membrane is continuous and tight around every penetration.

 

Schluter ® -KERDI-SEAL pipe and mixing valve seals are a smart upgrade because they fit snugly around pipes and valves, creating a tight, reliable bond that integrates seamlessly with the KERDI membrane. No cutting patches, no fiddling, and no risk of gaps that let moisture in. It’s a simple, foolproof way to protect your walls and stop leaks before they start.

 

Waterproofing All Corners

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When we talk about corners, we mean waterproofing in and around every:

• wall niche
• shower bench
• and curb

Corners are stress points and are one of the first places waterproofing can fail if not reinforced correctly. Pre-formed inside and outside corner pieces, along with continuous membrane coverage, ensure these areas stay fully sealed and protected from movement and water intrusion.

 

 

We always use Schluter ® -KERDI pre-formed, seamless corners made for waterproofing inside and outside corners. These products tie the whole system together and make sure every corner  is sealed tight to prevent leaks and mold-growth.

 

RELATED: Benefits of Waterproofing: Extend the Life of Your Bathroom Reno

Waterproofing Around a Window

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I love adding a window to a shower — the natural light makes a huge difference. But the installation has to be done right. A shower window is one of the easiest places for water to sneak in. If it’s not properly waterproofed, you’re looking at leaks, mold, and rot.

The sill, jambs, and frame all need to be fully wrapped with the right waterproofing membrane, sealed tight, and sloped so water drains away. Tile is not enough. Skip any of these steps and moisture will get into the framing, leading to serious structural
damage.

We wrap the window jamb with KERDI membrane, use preformed corners, and make sure the sill is sloped so water drains off. Schluter Systems makes this easy.

Pro Tip: We always advise against using wooden windows. Typically, we replace existing wooden windows with fiberglass or PVC ones made from non-organic materials. Plus, we always recommend using a quartz sill because it is naturally water-resistant.

 

Waterproofing isn’t just another step — it’s the foundation of a lasting, trouble-free bathroom. Missing spots like the curb, pipe penetrations, corners, or shower windows are the exact places water will find its way in and cause damage. That’s why you can’t cut corners or guess your way through it. Avoid these biggest waterproofing mistakes, and use the right products, like Schluter’s KERDI system, and cover every inch properly. Do it right the first time, and you’ll save yourself headaches, costly repairs, and a whole lot of frustration down the road.

 

UP NEXT: How To Make Your Bathroom Watertight

 

 

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