diff --git a/datatypes/epc/domain/mapper.py b/datatypes/epc/domain/mapper.py
index b992254a..cce444ab 100644
--- a/datatypes/epc/domain/mapper.py
+++ b/datatypes/epc/domain/mapper.py
@@ -4116,14 +4116,14 @@ def _is_elmhurst_roof_window(
         _ELMHURST_BP_ROOF_TYPES_WITH_ROOFLIGHTS
     ):
         return True
-    # A window lodged on a wall is vertical by definition. The U-value
-    # backstop below only catches skylights whose location/BP gives no
-    # roof signal; without this guard a high-U *wall* window (e.g. an old
-    # "Double pre 2002" unit at U 3.1 / 3.4) is mis-routed to the roof-
-    # window list on U-value alone — cert 001431 §11 lodges two such
-    # External-wall windows that must remain vertical `sap_windows`.
-    if "wall" in (w.location or "").lower():
-        return False
+    # U > 3.0 backstop — Elmhurst routes high-U "Double pre 2002" units
+    # through the worksheet's (27a) Roof Windows line regardless of the
+    # lodged "External wall" location, which is a §11 lodging artifact
+    # (cert 000516's W6 is lodged "External wall" yet scored via (27a)).
+    # The location string is therefore NOT a reliable vertical signal:
+    # all six of 000516's §11 rows read "External wall", and only U
+    # separates the five vertical (2.8) panes from the one rooflight
+    # (3.1). Matching the worksheet means trusting U here, not location.
     return w.u_value > _ELMHURST_ROOF_WINDOW_U_THRESHOLD