diff --git a/packages/nodes/src/column/definition.ts b/packages/nodes/src/column/definition.ts
index 57d4c5e9..080d2869 100644
--- a/packages/nodes/src/column/definition.ts
+++ b/packages/nodes/src/column/definition.ts
@@ -44,7 +44,9 @@ export const columnDefinition: NodeDefinition<typeof ColumnNode> = {
         const column = node as ColumnNodeType
         return {
           dimensions: [column.width, column.height, column.depth] as [number, number, number],
-          rotation: column.rotation,
+          // Column stores Y rotation as a scalar; the slab-overlap query
+          // expects the full Euler tuple.
+          rotation: [0, column.rotation, 0] as [number, number, number],
         }
       },
     },
diff --git a/packages/viewer/src/components/viewer/index.tsx b/packages/viewer/src/components/viewer/index.tsx
index fdcda841..d3d5dc54 100644
--- a/packages/viewer/src/components/viewer/index.tsx
+++ b/packages/viewer/src/components/viewer/index.tsx
@@ -5,6 +5,7 @@ import { useEffect, useMemo, useRef } from 'react'
 import * as THREE from 'three/webgpu'
 import { PERF_OVERLAY_ENABLED, pushGpuSample } from '../../lib/gpu-perf'
 import useViewer from '../../store/use-viewer'
+import { FloorElevationSystem } from '../../systems/floor-elevation/floor-elevation-system'
 import { GeometrySystem } from '../../systems/geometry/geometry-system'
 import { ErrorBoundary } from '../error-boundary'
 import { SceneRenderer } from '../renderers/scene-renderer'