diff --git a/packages/domain/src/domain/ml/rdsap_uvalues.py b/packages/domain/src/domain/ml/rdsap_uvalues.py
index 27069827..169c6cdb 100644
--- a/packages/domain/src/domain/ml/rdsap_uvalues.py
+++ b/packages/domain/src/domain/ml/rdsap_uvalues.py
@@ -417,6 +417,12 @@ def u_roof(
        as uninsulated.
     3. Table 18 age-band default.
     """
+    measured = _measured_u_from_description(description)
+    if measured is not None:
+        # Full-SAP cert lodges a measured roof U-value in the description
+        # ("Average thermal transmittance X W/m²K"); spec §5.11 opening
+        # clause defers to the assessor's value when present.
+        return measured
     if insulation_thickness_mm == 0 and _described_as_insulated(description):
         # Spec §5.11.4 (page 44 footnote): "If retrofit insulation
         # present of unknown thickness use 50 mm". The cert encodes
@@ -478,7 +484,16 @@ def u_floor(
     age band". The cert encodes "thickness unknown" as either a missing
     field (`insulation_thickness_mm=None`) or "NI" which
     `_parse_thickness_mm` returns as 0.
+
+    Full-SAP assessments lodge a measured floor U-value directly in
+    the description ("Average thermal transmittance X W/m²K"); when
+    present this supersedes the BS EN ISO 13370 calculation per spec
+    §5.12 opening clause ("Unless provided by the assessor the floor
+    U-value is calculated according to BS EN ISO 13370").
     """
+    measured = _measured_u_from_description(description)
+    if measured is not None:
+        return measured
     if area_m2 is None or perimeter_m is None or perimeter_m <= 0:
         return 0.7
     w = (wall_thickness_mm or 300) / 1000.0
diff --git a/packages/domain/src/domain/ml/tests/test_rdsap_uvalues.py b/packages/domain/src/domain/ml/tests/test_rdsap_uvalues.py
index afc96334..2bf0804d 100644
--- a/packages/domain/src/domain/ml/tests/test_rdsap_uvalues.py
+++ b/packages/domain/src/domain/ml/tests/test_rdsap_uvalues.py
@@ -466,6 +466,25 @@ def test_u_wall_uses_rdsap_unknown_thickness_default_of_50mm_when_insulated_but_
 # ----- Roofs -----
 
 
+def test_u_roof_description_with_measured_transmittance_returns_parsed_value() -> None:
+    # Arrange — ~1 140 corpus certs lodge a full-SAP measured roof
+    # U-value in the description, e.g. "Average thermal transmittance
+    # 0.11 W/m²K". The age-band cascade is bypassed: the assessor's
+    # measured/calculated value is used directly. Same contract as
+    # `u_wall` (S-B24) and `u_floor` (S-B29 cycle 1).
+
+    # Act
+    result = u_roof(
+        country=Country.ENG,
+        age_band="C",
+        insulation_thickness_mm=None,
+        description="Average thermal transmittance 0.11 W/m²K",
+    )
+
+    # Assert
+    assert result == pytest.approx(0.11, abs=0.001)
+
+
 def test_u_roof_ni_thickness_with_insulated_description_applies_50mm_per_section_5_11_4() -> None:
     # Arrange — 346 corpus certs lodge roof_insulation_thickness="NI"
     # (Not Indicated, parsed to 0 by _parse_thickness_mm). When the
@@ -621,6 +640,29 @@ def test_u_roof_explicit_thickness_beats_description() -> None:
 # ----- Floors -----
 
 
+def test_u_floor_description_with_measured_transmittance_returns_parsed_value() -> None:
+    # Arrange — ~1 391 corpus certs lodge a full-SAP measured floor
+    # U-value in the description, e.g. "Average thermal transmittance
+    # 0.18 W/m²K". The BS EN ISO 13370 calculation is bypassed: the
+    # assessor's measured/calculated value is used directly. Same
+    # contract as `u_wall` (S-B24).
+
+    # Act
+    result = u_floor(
+        country=Country.ENG,
+        age_band="B",
+        construction=None,
+        insulation_thickness_mm=None,
+        area_m2=100.0,
+        perimeter_m=40.0,
+        wall_thickness_mm=300,
+        description="Average thermal transmittance 0.18 W/m²K",
+    )
+
+    # Assert
+    assert result == pytest.approx(0.18, abs=0.001)
+
+
 def test_u_floor_ni_thickness_with_insulated_description_applies_50mm_per_table19_footnote() -> None:
     # Arrange — 2 413 corpus certs (~12%) lodge floors with
     # floor_insulation_thickness="NI" (Not Indicated, which our