diff --git a/datatypes/epc/domain/tests/test_from_rdsap_schema.py b/datatypes/epc/domain/tests/test_from_rdsap_schema.py
index a817414c..07fc7ddb 100644
--- a/datatypes/epc/domain/tests/test_from_rdsap_schema.py
+++ b/datatypes/epc/domain/tests/test_from_rdsap_schema.py
@@ -2710,22 +2710,48 @@ def test_rdsap_mappers_carry_main_heating_controls_display(
         (RdSapSchema17_1, EpcPropertyDataMapper.from_rdsap_schema_17_1, "17_1.json"),
         (RdSapSchema18_0, EpcPropertyDataMapper.from_rdsap_schema_18_0, "18_0.json"),
         (RdSapSchema20_0_0, EpcPropertyDataMapper.from_rdsap_schema_20_0_0, "20_0_0.json"),
+        (RdSapSchema19_0, EpcPropertyDataMapper.from_rdsap_schema_19_0, "19_0.json"),
+        (RdSapSchema21_0_0, EpcPropertyDataMapper.from_rdsap_schema_21_0_0, "21_0_0.json"),
     ],
 )
 def test_rdsap_mappers_map_mechanical_ventilation_kind(
     schema_cls: Any, mapper: Any, fixture: str
 ) -> None:
     # Calc-facing: an MVHR cert (mechanical_ventilation=4) must reach the §2
-    # ventilation cascade as MVHR, not be silently treated as natural. These
-    # three build a bare SapVentilation(sheltered_sides=…) and dropped the
-    # top-level mechanical_ventilation; 17.0 + 21.0.1 + full-SAP already map it
-    # (via _sap_17_1_ventilation / their own wiring). 19.0 + 21.0.0 set no
-    # sap_ventilation at all — a bigger, separate gap (see followups). Natural
+    # ventilation cascade as MVHR, not be silently treated as natural. 17.1 /
+    # 18.0 / 20.0.0 built a bare SapVentilation(sheltered_sides=…) and dropped
+    # the top-level mechanical_ventilation (fixed in #1333); 19.0 + 21.0.0 set
+    # no sap_ventilation at all, dropping the whole block (fixed here — the
+    # remaining ADR-0037 ventilation follow-up). 17.0 + 21.0.1 + full-SAP
+    # already map it (via _sap_17_1_ventilation / their own wiring). Natural
     # certs (code 0/5 → None) are unchanged, so the fix only moves genuine
-    # MEV/MVHR certs (ADR-0037 follow-up).
+    # MEV/MVHR certs.
     data = load(fixture)
     data["mechanical_ventilation"] = 4
 
     result = mapper(from_dict(schema_cls, data))
 
     assert result.sap_ventilation.mechanical_ventilation_kind == "MVHR"
+
+
+@pytest.mark.parametrize(
+    "schema_cls, mapper, fixture",
+    [
+        (RdSapSchema19_0, EpcPropertyDataMapper.from_rdsap_schema_19_0, "19_0.json"),
+        (RdSapSchema21_0_0, EpcPropertyDataMapper.from_rdsap_schema_21_0_0, "21_0_0.json"),
+    ],
+)
+def test_rdsap_19_0_21_0_0_construct_sap_ventilation_block(
+    schema_cls: Any, mapper: Any, fixture: str
+) -> None:
+    # 19.0 + 21.0.0 previously passed no `sap_ventilation=` at all → the
+    # EpcPropertyData default empty SapVentilation, dropping the entire §2
+    # block (sheltered_sides + kind). Mirroring 21.0.1, they now construct it.
+    # `sheltered_sides` derives from built_form per §S5 (both fixtures lodge
+    # built_form=2 Semi-Detached → 1 sheltered side); a missing/empty block
+    # would leave it None and over-count shelter via the cascade default of 2.
+    schema = from_dict(schema_cls, load(fixture))
+
+    result = mapper(schema)
+
+    assert result.sap_ventilation.sheltered_sides == 1