diff --git a/src/core/coping-geom.ts b/src/core/coping-geom.ts
index 9cd0d8a..5dcac46 100644
--- a/src/core/coping-geom.ts
+++ b/src/core/coping-geom.ts
@@ -14,11 +14,16 @@ export interface CopingGeom {
 /** P1 values: 끝단 높이 1000, 테이퍼 높이 1500, Level 폭 2100. Used when the input does not give them. */
 export const P1_COPING_GEOM: CopingGeom = { h1: 1000, h2: 1500, levelWidth: 2100 };
 
+/** Bar centre to the face of the coping, 127 mm (코핑철근.md §6.1, y_e). */
+export const SIDE_COVER_M = 0.127;
+
 /**
- * Side-row levels (EL m) of C12 / C13 from the Level underside. 코핑철근.md §6.1: z_0 = 하면 주철근 Level 높이 = 41.038,
- * which is the Level underside 40.911 plus 127; z_k = z_0 + k·250, and the break is z_6 = 42.538 (C12 below, C13 above).
- * So the rows keep this offset from the Level underside.
+ * Side-row levels (EL m) of C12 / C13 (코핑철근.md §6.1). z_0 = Level underside + 127 (the lowest bottom bar's Level
+ * height, 41.038 on P1), z_k = z_0 + k·250. The split is by height band:
+ *   C12 rows lie in the taper band (Level underside … end underside, height h2);
+ *   C13 rows lie in the end band (end underside … top, height h1).
+ * zBreak = end underside + 127 is where the taper line starts at the end face (P1: 42.538).
  */
-export function sideRowLevels(levelBottom: number): { zBottom: number; zBreak: number } {
-  return { zBottom: levelBottom + 0.377, zBreak: levelBottom + 1.627 };
+export function sideRowLevels(levelBottom: number, endBottom: number): { zBottom: number; zBreak: number } {
+  return { zBottom: levelBottom + SIDE_COVER_M + 0.25, zBreak: endBottom + SIDE_COVER_M };
 }
diff --git a/src/core/rebar/summary.ts b/src/core/rebar/summary.ts
index 9185f56..60a5200 100644
--- a/src/core/rebar/summary.ts
+++ b/src/core/rebar/summary.ts
@@ -190,7 +190,7 @@ export function rebarSummary(
     warnings.push({ code: 'RB-M01', message: `다주형 ${nCol}기둥: C14는 T형 기준으로 두었습니다 (기둥마다 반복 규칙 미정, Q-K11).`, target: 'coping' });
   }
   // Per row: two 일자 (side faces) and two ㄷ (one at each end), so 4 bars per row (코핑철근.md §6.2).
-  const levels = sideRowLevels(model.levelBottom);
+  const levels = sideRowLevels(model.levelBottom, model.endBottom);
   const side = copingSideBars(model.copingL * 1000, levels.zBottom, levels.zBreak, model.copingGeom);
   const hook = model.copingB * 1000 - 2 * 127 + 2 * SIDE_HOOK_LEG; // ㄷ body across the width + two legs
   const c12Range = side.c12.length ? `${Math.round(side.c12[0].straight)}–${Math.round(side.c12[side.c12.length - 1].straight)}` : '—';
diff --git a/src/view/rebar3d.ts b/src/view/rebar3d.ts
index 9103bdf..e0877cf 100644
--- a/src/view/rebar3d.ts
+++ b/src/view/rebar3d.ts
@@ -204,7 +204,7 @@ export function buildRebar3D(m: PierModel, common: Material = DEFAULT_MATERIAL,
     // and two ㄷ bars: a body across the width at x_w, 25.4 above the row, with legs 1525 inward along the faces.
     const sideFace = B / 2 - 0.127;
     const dSide = NOMINAL_DIAMETER.H25;
-    const levels = sideRowLevels(m.levelBottom);
+    const levels = sideRowLevels(m.levelBottom, m.endBottom);
     const side = copingSideBars(L * 1000, levels.zBottom, levels.zBreak, m.copingGeom);
     for (const [name, rows] of [['C12', side.c12], ['C13', side.c13]] as const) {
       for (const r of rows) {
diff --git a/tests/coping-geom.test.ts b/tests/coping-geom.test.ts
index 44db75a..df7b2cb 100644
--- a/tests/coping-geom.test.ts
+++ b/tests/coping-geom.test.ts
@@ -1,6 +1,7 @@
 import { describe, expect, it } from 'vitest';
 import { buildPier } from '../src/core/geometry';
-import { P1_COPING_GEOM, sideRowLevels } from '../src/core/coping-geom';
+import { P1_COPING_GEOM, SIDE_COVER_M, sideRowLevels } from '../src/core/coping-geom';
+import { sideRows } from '../src/core/rebar/coping';
 import { shearUHeight, shearULength } from '../src/core/rebar/coping';
 import { rebarSummary } from '../src/core/rebar/summary';
 import { buildRebar3D } from '../src/view/rebar3d';
@@ -45,7 +46,7 @@ describe('① 코핑 끝단 높이 h1 · 테이퍼 높이 h2 · Level 폭 (1단
   });
 
   it('side-row levels keep their P1 values from the Level underside (assumption, 명세 확인 필요)', () => {
-    const levels = sideRowLevels(40.911);
+    const levels = sideRowLevels(40.911, 42.411);
     expect(levels.zBottom).toBeCloseTo(41.288, 6);
     expect(levels.zBreak).toBeCloseTo(42.538, 6);
   });
@@ -59,3 +60,28 @@ describe('① 코핑 끝단 높이 h1 · 테이퍼 높이 h2 · Level 폭 (1단
     expect(buildRebar3D(changed).byName.get('C10')!.length).toBeGreaterThan(0);
   });
 });
+
+describe('C12 in the taper band (h2), C13 in the end band (h1)', () => {
+  const bands = (input: Parameters<typeof buildPier>[0]) => {
+    const m = buildPier(input);
+    const lv = sideRowLevels(m.levelBottom, m.endBottom);
+    const rows = sideRows(lv.zBottom, lv.zBreak);
+    return { m, rows };
+  };
+  it.each([
+    ['P1', {}],
+    ['h1 800', { copingH1Mm: 800 }],
+    ['h1 1200', { copingH1Mm: 1200 }],
+    ['h2 1800', { copingH2Mm: 1800 }],
+  ])('%s: every C12 row is in the taper band and every C13 row in the end band', (_name, change) => {
+    const { m, rows } = bands({ ...loadP1(), ...change });
+    for (const z of rows.c12) {
+      expect(z).toBeGreaterThanOrEqual(m.levelBottom - 1e-9);
+      expect(z).toBeLessThan(m.endBottom + SIDE_COVER_M);
+    }
+    for (const z of rows.c13) {
+      expect(z).toBeGreaterThanOrEqual(m.endBottom + SIDE_COVER_M - 1e-9);
+      expect(z).toBeLessThanOrEqual(m.copingRefTop);
+    }
+  });
+});