Tile (C-54) · Lesson 3 of 7

Shower Receptor: Slope, Curb, Lining Height and Flood Test

"Shower Receptor: Slope, Curb, Lining Height and Flood Test" is lesson 3 of 7 in the Tile (C-54) Learning Hub. It opens with "A Site-Built Receptor Is a Lined, Sloped Pan" and works through 6 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. A Site-Built Receptor Is a Lined, Sloped Pan
  2. Two Slopes: Lining 1/4 Inch Per Foot, Finished Floor 1/8 to 1/2
  3. Curb Height and Doors
  4. Lining Height and Fastening
  5. Flood Test Before the Tile Bed
  6. Slope Math: Distance Times Slope

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Find the distances to the drain" through "Check the size and test the pan".

What you'll be able to do

  • Explain the main idea of "Shower Receptor: Slope, Curb, Lining Height and Flood Test" in plain language you can use on the exam.
  • Apply this step with confidence: "Curb Height and Doors".
  • Apply this step with confidence: "Lining Height and Fastening".
  • Apply this step with confidence: "Flood Test Before the Tile Bed".
  • Apply this step with confidence: "Slope Math: Distance Times Slope".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Shower Receptor: Slope and Curb MathDRAIN3 inCURBLining pitch: 1/4 in per ft to weep holes (408.8)Lining turns up the wallat least 3 in above thetop of the finished dam (408.8)Back wall at least 1 in higher than curb18 in = 1.5 ft18 in = 1.5 ftSECTION ACROSS THE 36 IN WIDTH (slope exaggerated)JOB: 60 x 36 INDrain at the center30 in to the end walls18 in to the side wallsSlope used: 1/4 in per ft(code range 1/8 to 1/2)End wall: 30 in = 2.5 ft2.5 x 1/4 = 5/8 in fallSide/curb: 18 in = 1.5 ft1.5 x 1/4 = 3/8 in fallCurb: 3 in above drain(code range 2 to 9 in)Finished slope 1/4 in per ft is inside the 1/8 to 1/2 in per ft range (CPC 408.6): PASSCurb 3 in above the drain is inside 2 to 9 in and 1 in or more below the sides: PASS2025 California Plumbing Code 408.6 (slope, curb); 408.8 (lining 3 in above dam, pitch 1/4 in per ft)Flood test: at least 2 in of water for at least 15 minutes (CPC 408.8.5)CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: A Site-Built Receptor Is a Lined, Sloped Pan

2025 California Plumbing Code (CPC) Section 408.8 says a shower receptor built on site shall be watertight, made of approved dense, nonabsorbent, non-corrosive materials, adequately reinforced, with an approved flanged floor drain that makes a watertight joint, and with smooth, impervious, durable surfaces. The subfloor and the rough side of the walls are first lined with sheet plastic, lead or copper, or other durable and watertight material, and the tile goes over that. The lining, not the tile and grout, is the watertight layer the code describes.

Step 2: Two Slopes: Lining 1/4 Inch Per Foot, Finished Floor 1/8 to 1/2

CPC 408.8 prints the lining pitch: lining materials are pitched 1/4 inch per foot (20.8 mm/m) to weep holes in the subdrain, over a smooth and solidly formed subbase. CPC 408.6 prints the finished floor slope: it shall slope uniformly from the sides toward the drain not less than 1/8 inch per foot (10.4 mm/m) and not more than 1/2 inch per foot (41.6 mm/m). So a 1/4 inch per foot slope is the code pitch under the lining and is also inside the finished-floor range.

The remaining 4 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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