diff --git a/B08_Quantity/B08_Quantity_Router_Material.py b/B08_Quantity/B08_Quantity_Router_Material.py
index 09edd1f7..09fbb35e 100644
--- a/B08_Quantity/B08_Quantity_Router_Material.py
+++ b/B08_Quantity/B08_Quantity_Router_Material.py
@@ -57,6 +57,7 @@ router = APIRouter(prefix="/api/projects", tags=["B08 Quantity"])
 
 def _collect_structures(
     project_root: str,
+    designs: list[dict[str, Any]] | None = None,
 ) -> tuple[list[dict[str, Any]], dict[str, str], list[str]]:
     """전개 대상 구조물·타입명·건너뛴 사유를 함께 낸다.
 
@@ -66,7 +67,7 @@ def _collect_structures(
     ⚠ 관 지점 종류(`managed_by`)가 `structures.json` 에 옛 저장분으로 남아 있어도 안 셈 —
       관 지점 정본이 주인이라 두 번 세지 않음(구조물 집계표와 같은 규칙).
     """
-    from B08_Quantity.B08_Quantity_Engine_Pipe import facility_structures
+    from B08_Quantity.B08_Quantity_Engine_Pipe import extra_walls_from_designs, facility_structures
     from common_util.common_util_drainage_pipes import pipe_points_path_in, read_pipe_points_file
 
     _revision, items = load_structures(project_root)
@@ -102,7 +103,9 @@ def _collect_structures(
             continue
         targets.append(payload)
     points = read_pipe_points_file(pipe_points_path_in(Path(project_root)))
-    for row in facility_structures([point.as_dict() for point in points]):
+    # 다단 추가 기슭막이(④) — 횡단 설계에 남은 「선 다단 벽 목록」도 줄로 세움.
+    extra_walls = extra_walls_from_designs(designs)
+    for row in facility_structures([point.as_dict() for point in points], extra_walls):
         for type_id in (row["type_id"], row.get("attachment_parent_type")):
             if type_id in types:
                 names[type_id] = types[type_id].name
@@ -190,7 +193,7 @@ async def get_material_summary(project_id: UUID) -> JSONResponse:
         )
 
     try:
-        structures, names, skipped = _collect_structures(project_root)
+        structures, names, skipped = _collect_structures(project_root, await _designs(project_id))
     except Exception:
         logger.exception("B08 구조물 정본 읽기 실패: project_id=%s", project_id)
         return JSONResponse(
@@ -405,7 +408,7 @@ async def project_haul_inputs(project_id: UUID) -> dict[str, Any]:
     try:
         stored_path = await run_with_connection(get_project_storage_relative_path, project_id)
         project_root = resolve_stored_project_path(stored_path)
-        structures, names, _skipped = _collect_structures(project_root)
+        structures, names, _skipped = _collect_structures(project_root, await _designs(project_id))
         settings = quantity_settings(project_root)
         unit_table = build_unit_table(
             structures,
@@ -448,7 +451,7 @@ async def get_handoff(project_id: UUID) -> JSONResponse:
             content={"status": "error", "message": "프로젝트 저장 폴더를 찾지 못했습니다."},
         )
 
-    structures, names, skipped = _collect_structures(project_root)
+    structures, names, skipped = _collect_structures(project_root, await _designs(project_id))
     settings = quantity_settings(project_root)
     modes = await _section_modes(project_id)
     unit_table = build_unit_table(
@@ -539,7 +542,7 @@ async def structure_bill_prices(project_id: UUID, build: Any) -> dict[str, dict[
 
     stored_path = await run_with_connection(get_project_storage_relative_path, project_id)
     project_root = resolve_stored_project_path(stored_path)
-    structures, names, _skipped = _collect_structures(project_root)
+    structures, names, _skipped = _collect_structures(project_root, await _designs(project_id))
     settings = quantity_settings(project_root)
     modes = await _section_modes(project_id)
     unit_table = build_unit_table(