<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=2223002471257760&amp;ev=PageView&amp;noscript=1">

CTEF Blog - About Tile Education and Installer Certification

Does Your Tile Slope To the Drain?

[fa icon="calendar"] Nov 28, 2017 8:30:00 AM / by Scott Carothers

Scott Carothers

Does Your Tile Slope To the Drain?

When you install tile in wet areas, do you ensure that everything slopes to the drain? If not, please read below.

Let's consider showers.  Showers can be a beautiful part of the bathroom especially when tile is part of the finished product.  The beauty, though, will not be long lasting if the installation standards and best practices for tile installation are not followed.

Showers are Wet Areas

Although the Introduction section of the ANSI document is not a part of the A108 installation standard, it defines a wet area in section 2:18 as,

“Tile surfaces that are either soaked, saturated, or subjected to moisture or liquids (usually water) such as in gang showers, tub enclosures, showers, floors adjacent to curbless showers, laundries, saunas, steam rooms, swimming pools, or exterior areas.” 

This means the shower is considered a “wet” area.

Not only that, showers are intensely and inherently wet. As we've mentioned in a previous article, showers are harsh environments which are not very forgiving when the installation has been poorly constructed by misguided "tile placers" (you can't call them installers due to their lack of quality work). That's why employing Certified Tile Installers is so important.)

How to Deal with Wet Areas?

So how do we deal with tile installations in wet areas such as showers?

Step 1: Floor Tile Must Slope to the Drain

In a stall shower, the plumbing code requires the floor be sloped one quarter (1/4) of an inch per foot in order to carry the water effectively to the drain. 

  • This slope, according to the TCNA Handbook is called “sloped fill” or commonly known as the pre-slope.  This sloped material is installed under the pan liner (waterproofing membrane).
  • With a tape measure, determine the distance between the drain and the farthest corner of the shower. As seen in the photo below, this distance is 26".
  • Divide that distance in feet (inches divided by 12) by four to find how much slope you need. 26" divided by 12 = 2.167 divided by 4 = 0.4417 or slightly more than 1/2" of slope.
  • Mark the height of slope along the wall with a pencil and install the sloped fill..


By the way, the floor must also be flat.  This means that there can be no low spots for bird baths which could retain water.

>> A Flat Floor vs. a Level Floor: What's the Difference?

Step 2:  Slope Shower Ledges, Rims, Sills, Seats and Thresholds

It's not just the floor that you need to consider for sloping in showers.

According to the ANSI standard A108.01-3.6.4,

“All horizontal ledges/rims shall have a slope such that any fluid on their surfaces flows toward the drain.”

Additionally, the Tile Council of North America (TCNA) Handbook, all bathtub and stall shower details contain this note,

“All horizontal surfaces, for example shower seats, sills, curbs, etc., must slope towards drain or other surface sloped toward drain.  Where present, waterproofing also must be sloped."

Step 3: All Shower Surfaces Must Slope to the Drain

All these notes and standards clearly show that all surfaces in a shower, be it residential or commercial, must carry the water to the drain and, therefore, must be sloped. 

This would include other surfaces in the shower such as the curb or threshold under the door, the shelves of a niche, a corner shelf, a shaving shelf, a seat, and a windowsill, such as the one in the photo below.     

Any Slope vs. a Tile Slope to the Drain

Let's examine the photo below where these requirements weren't followed.

All Shower Surfaces Must Slope to the Drain

This shower, in an upscale hotel, includes a window (and sill) between the shower and the bathroom.  You can easily see the puddled water on the sill which is actually sloped not to the drain, but toward the window.  Each time the shower is used, water collects on the sill, remaining there until the cleaning staff dries the surface. 

Unfortunately, this standing water has found its way to the other side of the wall causing the drywall to deteriorate.

The better approach would have been to slope the tiled window sill toward the shower drain so as to avoid those unwanted water puddles.

The Solution: Pay Attention to Details!

Attention to this and other details in wet areas will provide a shower that will remain beautiful and functional for many years. 

Similarly, using qualified labor such as a Certified Tile Installer (CTI) or journeyman installer assures the end user that this type of problem does not occur.   

Do You Ensure that Your Tile Work Slopes to the Drain? 

What situations have you encountered where tile work didn't slope properly? How did you address the situation?

If you haven't already, consider becoming a Certified Tile Installer (CTI). As a CTI, you set yourself apart from the crowd and know how to anticipate tile installation problems before they occur.

Do it right the first time and get paid accordingly.

Thanks for reading.


Learn More About Becoming a Certified Tile Installer Click Here to Download the CTI Kit. 

Topics: Ask Scott, Installing Tile TIps

Subscribe to Email Updates

Explore Beautiful Tile Installations  Created by  Certified Tile Installers
Click Here to Learn About  Becoming a CTEF Sponsor

Blogs Written By CTEF Sponsors & Friends

Crossville's Latest News and Views

DalTile's From the Floor Up

Joseph Lundgren Consulting In the News Blog

MAPEI's Tech Talk Blog

Neuse Tile Services Blog

TEC Specialty's Expert Advice

Looking for Tips on How to  Select  Your Next   Tile Contractor?   ~  Click Here to  Download! ~