diff --git a/domain/epc/property_overlays/main_heating_system_overlay.py b/domain/epc/property_overlays/main_heating_system_overlay.py
index 1110b1f68..f99a24f5c 100644
--- a/domain/epc/property_overlays/main_heating_system_overlay.py
+++ b/domain/epc/property_overlays/main_heating_system_overlay.py
@@ -140,6 +140,12 @@ _ELECTRIC_UNDERFLOOR_CODES = frozenset({421, 422, 424})
 # generator's `is_heat_network_main` gate read as community heating: no heating
 # upgrade was offered at all and the baseline mis-rated 51 vs 67 (ADR-0050).
 _UNDERFLOOR_CATEGORY = 8
+# SAP Table 4e Group 7 underfloor control: 2701 ("no time or thermostatic
+# control of room temperature", +0.3 C) is the conservative default when the
+# landlord named only the system — the largest mean-internal-temperature
+# adjustment in the group, so an unobserved control is never over-credited
+# (the underfloor mirror of storage-manual 2401 and room-heater 2601, ADR-0050).
+_UNDERFLOOR_CONTROL = 2701
 
 # Heat pumps (SAP Table 4a 211-224 wet, 521-527 warm-air) are category 4 and
 # unambiguously electric (natural fuel 29). Modellable on the default code's SPF
@@ -278,6 +284,8 @@ def _control_for(code: int) -> Optional[int]:
         return _FULL_BOILER_CONTROL
     if code in _CATEGORY_10_ROOM_HEATER_CODES or code in _ELECTRIC_ROOM_HEATER_CODES:
         return _ROOM_HEATER_CONTROL
+    if code in _ELECTRIC_UNDERFLOOR_CODES:
+        return _UNDERFLOOR_CONTROL
     return None