diff --git a/domain/epc/property_overlays/glazing_overlay.py b/domain/epc/property_overlays/glazing_overlay.py
index 6ee05030..d692181d 100644
--- a/domain/epc/property_overlays/glazing_overlay.py
+++ b/domain/epc/property_overlays/glazing_overlay.py
@@ -19,7 +19,11 @@ from domain.modelling.simulation import EpcSimulation, GlazingOverlay
 # Canonical glazing description → SAP10 glazing-type code (the Table 24 /
 # `u_window` cascade enum, `_GLAZING_CODE_TO_UWINDOW` in heat_transmission).
 _GLAZING_CODES: dict[str, int] = {
+    "Single glazing": 1,
     "Double glazing, 2002 or later": 2,
+    "Double glazing, pre-2002": 3,
+    "Triple glazing, pre-2002": 6,
+    "Triple glazing, 2002 or later": 9,
 }