diff --git a/datatypes/epc/domain/mapper.py b/datatypes/epc/domain/mapper.py
index b992254a..de7297a4 100644
--- a/datatypes/epc/domain/mapper.py
+++ b/datatypes/epc/domain/mapper.py
@@ -4868,6 +4868,16 @@ _ELMHURST_CYLINDER_INSULATION_LABEL_TO_SAP10: Dict[str, int] = {
     "Jacket": 2,
 }
 
+# Elmhurst §15.1 "Insulated" labels for an uninsulated cylinder. These are
+# lodged (not absent), but an uninsulated cylinder has no insulation *type* —
+# per the no-misleading-insulation convention it maps to
+# `cylinder_insulation_type = None` rather than naming a material. The lodged
+# §15.1 "Insulation Thickness" (0 mm) carries the storage-loss signal the
+# cascade's SAP 10.2 Table 2 dispatch needs.
+_ELMHURST_CYLINDER_NO_INSULATION_LABELS: frozenset[str] = frozenset({
+    "No Insulation",
+})
+
 
 # Elmhurst §15.0 "Water Heating Fuel Type" labels that route to solid-
 # fuel Table 32 codes (Anthracite, House coal, Wood logs/pellets, etc.).
@@ -4978,6 +4988,8 @@ def _elmhurst_cylinder_insulation_code(
     mapping dict — see `_elmhurst_cylinder_size_code` rationale."""
     if not cylinder_present or cylinder_insulation_label is None:
         return None
+    if cylinder_insulation_label in _ELMHURST_CYLINDER_NO_INSULATION_LABELS:
+        return None
     code = _ELMHURST_CYLINDER_INSULATION_LABEL_TO_SAP10.get(cylinder_insulation_label)
     if code is None:
         raise UnmappedElmhurstLabel("cylinder_insulation", cylinder_insulation_label)
diff --git a/tests/datatypes/epc/domain/test_mapper_cylinder_insulation.py b/tests/datatypes/epc/domain/test_mapper_cylinder_insulation.py
new file mode 100644
index 00000000..01869baa
--- /dev/null
+++ b/tests/datatypes/epc/domain/test_mapper_cylinder_insulation.py
@@ -0,0 +1,49 @@
+"""Mapper boundary: the Elmhurst §15.1 "Insulated" cylinder label.
+
+A cylinder lodged "No Insulation" is an uninsulated cylinder, not a mapper
+gap. Per the no-misleading-insulation convention it maps to
+`cylinder_insulation_type = None` (don't name an insulation material on an
+uninsulated surface) rather than raising `UnmappedElmhurstLabel`. This
+unblocks parsing every solar example cert (the solar `before` cert lodges
+"No Insulation").
+"""
+
+from datatypes.epc.domain.mapper import (
+    UnmappedElmhurstLabel,
+    _elmhurst_cylinder_insulation_code,  # pyright: ignore[reportPrivateUsage]
+)
+
+
+def test_no_insulation_label_maps_to_none() -> None:
+    # Arrange
+    label = "No Insulation"
+
+    # Act
+    code = _elmhurst_cylinder_insulation_code(label, cylinder_present=True)
+
+    # Assert
+    assert code is None
+
+
+def test_foam_label_still_maps_to_factory_code() -> None:
+    # Arrange
+    label = "Foam"
+
+    # Act
+    code = _elmhurst_cylinder_insulation_code(label, cylinder_present=True)
+
+    # Assert
+    assert code == 1
+
+
+def test_unknown_label_still_raises() -> None:
+    # Arrange
+    label = "Spray-on unicorn felt"
+
+    # Act / Assert
+    try:
+        _elmhurst_cylinder_insulation_code(label, cylinder_present=True)
+        raised = False
+    except UnmappedElmhurstLabel:
+        raised = True
+    assert raised