diff --git a/backend/documents_parser/extractor.py b/backend/documents_parser/extractor.py
index 822f7907..47022c55 100644
--- a/backend/documents_parser/extractor.py
+++ b/backend/documents_parser/extractor.py
@@ -66,9 +66,11 @@ class PasHubRdSapSiteNotesExtractor:
         val = self._get_in(list_to_process, key)
         return val is not None and val.lower() != "not known"
 
-    def _wall_thickness_in(self, list_to_process: List[str]) -> int:
+    def _wall_thickness_in(self, list_to_process: List[str]) -> Optional[int]:
         val = self._get_in(list_to_process, "Wall thickness:")
-        return int(val.split()[0]) if val else 0
+        if not val or val.split()[0].lower() == "unmeasurable":
+            return None
+        return int(val.split()[0])
 
     def _section(self, start: str, end: str) -> List[str]:
         try:
@@ -83,10 +85,17 @@ class PasHubRdSapSiteNotesExtractor:
     def extract_inspection_metadata(self) -> InspectionMetadata:
         try:
             addr_start = self.text_list.index("Property Address:") + 1
-            addr_end = self.text_list.index("Property Photo", addr_start)
-            property_address = ", ".join(
-                t.rstrip(",") for t in self.text_list[addr_start:addr_end]
-            )
+            try:
+                addr_end = self.text_list.index("Property Photo", addr_start)
+                address_tokens = self.text_list[addr_start:addr_end]
+            except ValueError:
+                addr_end = self.text_list.index("RdSAP Assessment", addr_start)
+                address_tokens = []
+                for t in self.text_list[addr_start:addr_end]:
+                    if not t or t.startswith("Page "):
+                        break
+                    address_tokens.append(t)
+            property_address = ", ".join(t.rstrip(",") for t in address_tokens)
         except ValueError:
             property_address = ""
 
diff --git a/backend/documents_parser/tests/fixtures/PasHubSiteNotes_7.pdf b/backend/documents_parser/tests/fixtures/PasHubSiteNotes_7.pdf
new file mode 100644
index 00000000..29d083c6
Binary files /dev/null and b/backend/documents_parser/tests/fixtures/PasHubSiteNotes_7.pdf differ
diff --git a/backend/documents_parser/tests/fixtures/pashub_site_notes_7_text.json b/backend/documents_parser/tests/fixtures/pashub_site_notes_7_text.json
new file mode 100644
index 00000000..933535cf
--- /dev/null
+++ b/backend/documents_parser/tests/fixtures/pashub_site_notes_7_text.json
@@ -0,0 +1,670 @@
+[
+  "SMART EPC: Record of",
+  "Inspection & Site Notes",
+  "Inspection Surveyor:",
+  "Dave Elliott",
+  "E-Mail Address:",
+  "davejohns36@icloud.com",
+  "Report Reference:",
+  "Not Applicable",
+  "Created On:",
+  "12 September 2025",
+  "Date of Inspection:",
+  "08 September 2025",
+  "Property Address:",
+  "Flat 3,",
+  "29 Watcombe Circus,",
+  "NOTTINGHAM,",
+  "NG5 2DU",
+  "Page 1",
+  "",
+  "Photo of electricity meter:",
+  "Single Smart Meter",
+  "RdSAP Assessment",
+  "General",
+  "Confirm you have checked for the existence of an",
+  "EPC before carrying out another energy assessment.",
+  "Yes",
+  "Does an EPC exist at the point of carrying out this",
+  "energy assessment?",
+  "No",
+  "Inspection Date:",
+  "08/09/2025",
+  "Transaction Type:",
+  "None of the Above",
+  "Tenure:",
+  "Rented Social",
+  "Type of Property:",
+  "Maisonette",
+  "Detachment Type:",
+  "Semi-Detached",
+  "Flat Type:",
+  "Mid-floor",
+  "Flat Location:",
+  "3",
+  "Corridor Type:",
+  "Unheated Corridor",
+  "Unheated corridor wall length:",
+  "6.59 m",
+  "Number of storeys:",
+  "2 Storeys",
+  "Terrain Type:",
+  "Suburban",
+  "Number of Extensions:",
+  "2 Extensions",
+  "Is an electricity smart meter present?",
+  "Yes",
+  "Electric meter type:",
+  "Single",
+  "Is the dwelling export-capable?",
+  "No",
+  "Is mains gas available?",
+  "Yes",
+  "Is there a gas smart meter?",
+  "No",
+  "Is the gas meter accessible?",
+  "Yes",
+  "Page 2",
+  "",
+  "Photo of Gas Meter:",
+  "Gas Meter",
+  "External indicators of Solid Brick construction:",
+  "Brick Pattern",
+  "Select Measurements Location:",
+  "Internal",
+  "Building Construction",
+  "Main Building",
+  "Age Range:",
+  "1900-1929",
+  "Record indicators of property age:",
+  "Property checker",
+  "Walls - Construction Type:",
+  "Solid brick",
+  "Record external indicators of Solid Brick",
+  "Construction:",
+  "consistent with build age",
+  "Walls - Insulation Type:",
+  "As built",
+  "Thermal conductivity of wall insulation:",
+  "Unknown",
+  "Wall U-Value known?",
+  "Not Known",
+  "Wall thickness:",
+  "280 mm",
+  "Page 3",
+  "",
+  "Photo wall thickness:",
+  "Wall Measurements",
+  "Wall Dry-Lined?",
+  "No",
+  "Party wall construction type:",
+  "Solid Masonry, Timber Frame, or System Built",
+  "Floor type:",
+  "Other dwelling below",
+  "Extension 1",
+  "Age Range:",
+  "1900-1929",
+  "Record indicators of property age:",
+  "Property checker",
+  "Walls - Construction Type:",
+  "Solid brick",
+  "Record external indicators of Solid Brick",
+  "Construction:",
+  "headers and stretchers in brick bond",
+  "Walls - Insulation Type:",
+  "As built",
+  "Thermal conductivity of wall insulation:",
+  "Unknown",
+  "Wall U-Value known?",
+  "Not Known",
+  "Wall thickness:",
+  "280 mm",
+  "Wall Dry-Lined?",
+  "Yes",
+  "Party wall construction type:",
+  "Solid Masonry, Timber Frame, or System Built",
+  "Floor type:",
+  "Other dwelling below",
+  "Extension 2",
+  "Age Range:",
+  "1900-1929",
+  "Record indicators of property age:",
+  "Property checker",
+  "Walls - Construction Type:",
+  "Solid brick",
+  "Record external indicators of Solid Brick",
+  "Construction:",
+  "headers and stretchers in brick bond",
+  "Walls - Insulation Type:",
+  "As built",
+  "Thermal conductivity of wall insulation:",
+  "Unknown",
+  "Page 4",
+  "",
+  "Loft insulation:",
+  "Loft",
+  "Loft insulation:",
+  "Loft",
+  "Wall U-Value known?",
+  "Not Known",
+  "Wall thickness:",
+  "280 mm",
+  "Wall Dry-Lined?",
+  "Yes",
+  "Party wall construction type:",
+  "Solid Masonry, Timber Frame, or System Built",
+  "Floor type:",
+  "Other dwelling below",
+  "Building Measurements",
+  "Area (m2)",
+  "Height (m)",
+  "Heat Loss Perimeter (m)",
+  "PWL (m)",
+  "Main Building",
+  "Floor 1",
+  "39.5",
+  "3.58",
+  "11.02",
+  "15.21",
+  "Floor 0",
+  "23.06",
+  "2.87",
+  "11.72",
+  "10.8",
+  "Extension 1",
+  "Floor 1",
+  "3.43",
+  "3.58",
+  "4.97",
+  "1",
+  "Floor 0",
+  "3.43",
+  "2.87",
+  "4.97",
+  "1",
+  "Extension 2",
+  "Floor 0",
+  "1.81",
+  "3.58",
+  "4.96",
+  "1",
+  "Roof Space",
+  "Main Building",
+  "Roofs - Construction Type:",
+  "Pitched roof (Slates or tiles), Access to loft",
+  "Roofs - Insulation At:",
+  "Joists",
+  "Roof U-Value:",
+  "Not Known",
+  "Roofs - Insulation Thickness:",
+  "225 mm",
+  "Page 5",
+  "",
+  "Loft insulation:",
+  "Loft",
+  "Loft insulation:",
+  "Loft",
+  "Loft insulation:",
+  "Loft",
+  "Loft insulation:",
+  "Loft",
+  "Loft insulation:",
+  "Loft",
+  "Loft insulation:",
+  "Loft",
+  "Loft insulation:",
+  "Loft",
+  "Loft insulation:",
+  "Loft",
+  "Page 6",
+  "",
+  "Loft insulation:",
+  "Loft",
+  "Indicators of Solid Brick Wall Construction in roof space:",
+  "solid wall construction visible to gables",
+  "Record indicators of Solid Brick Wall Construction in",
+  "roof space:",
+  "solid wall construction visible to gables",
+  "Extension 1",
+  "Roofs - Construction Type:",
+  "Flat",
+  "Roofs - Insulation At:",
+  "Unknown",
+  "Record indicators of Solid Brick Wall Construction in",
+  "roof space:",
+  "solid wall construction visible at eaves",
+  "Extension 2",
+  "Roofs - Construction Type:",
+  "Flat",
+  "Roofs - Insulation At:",
+  "Unknown",
+  "Record indicators of Solid Brick Wall Construction in",
+  "roof space:",
+  "Couldn\u2019t enter",
+  "Page 7",
+  "",
+  "Alternative Wall",
+  "Main Building",
+  "Alternative Wall 1",
+  "Construction type:",
+  "Solid brick",
+  "Record external indicators of Solid Brick",
+  "Construction:",
+  "consistent with building age, no visible cavity trays",
+  "Insulation Type:",
+  "As Built",
+  "Sheltered wall?",
+  "Yes",
+  "Thermal conductivity of wall insulation:",
+  "Unknown",
+  "Wall thickness:",
+  "280 mm",
+  "Wall Dry-Lined?",
+  "Yes",
+  "Windows",
+  "Window 1",
+  "Window location:",
+  "Main Building",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.2 m",
+  "Window width:",
+  "0.8 m",
+  "Orientation:",
+  "South West",
+  "Window 2",
+  "Window location:",
+  "Extension 1",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.65 m",
+  "Window width:",
+  "0.52 m",
+  "Orientation:",
+  "East",
+  "Page 8",
+  "",
+  "Window 3",
+  "Window location:",
+  "Extension 1",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.95 m",
+  "Window width:",
+  "0.86 m",
+  "Orientation:",
+  "East",
+  "Window 4",
+  "Window location:",
+  "Extension 1",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.76 m",
+  "Window width:",
+  "0.65 m",
+  "Orientation:",
+  "North",
+  "Window 5",
+  "Window location:",
+  "Extension 1",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.68 m",
+  "Window width:",
+  "0.68 m",
+  "Orientation:",
+  "East",
+  "Page 9",
+  "",
+  "Window 6",
+  "Window location:",
+  "Extension 1",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.84 m",
+  "Window width:",
+  "1.18 m",
+  "Orientation:",
+  "North East",
+  "Window 7",
+  "Window location:",
+  "Extension 1",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.76 m",
+  "Window width:",
+  "0.65 m",
+  "Orientation:",
+  "North",
+  "Window 8",
+  "Window location:",
+  "Extension 2",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.82 m",
+  "Window width:",
+  "0.84 m",
+  "Orientation:",
+  "South East",
+  "Page 10",
+  "",
+  "Window 9",
+  "Window location:",
+  "Extension 2",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.65 m",
+  "Window width:",
+  "0.5 m",
+  "Orientation:",
+  "South",
+  "Window 10",
+  "Window location:",
+  "Extension 2",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.71 m",
+  "Window width:",
+  "0.47 m",
+  "Orientation:",
+  "East",
+  "Window 11",
+  "Window location:",
+  "Extension 2",
+  "Window wall type:",
+  "External wall",
+  "Glazing Type:",
+  "Double glazing, Unknown install date",
+  "Window type:",
+  "Window",
+  "Window frame type:",
+  "Wooden or PVC",
+  "What size is the glazing gap?",
+  "16 mm or more",
+  "Is the window draught proofed?",
+  "Yes",
+  "Are there permanent shutters present?",
+  "No",
+  "Window height:",
+  "1.2 m",
+  "Window width:",
+  "0.8 m",
+  "Orientation:",
+  "South West",
+  "Page 11",
+  "",
+  "Heating & Hot Water",
+  "Main Heating Systems",
+  "Main Heating 1",
+  "How would you like to select the Heating System?",
+  "PCDF Search",
+  "System type:",
+  "Boiler with radiators or underfloor heating",
+  "Product Id",
+  "15030",
+  "Manufacturer",
+  "Baxi",
+  "Model",
+  "Duo-tec Combi",
+  "Orig Manuf",
+  "Baxi Heating",
+  "Fuel",
+  "Mains gas",
+  "S. Efficiency",
+  "0",
+  "Type",
+  "Combi",
+  "Condensing",
+  "Yes",
+  "Year",
+  "2006 - 2008",
+  "Mount",
+  "Wall",
+  "Open Flue",
+  "Room-sealed",
+  "Fan Assist",
+  "Yes",
+  "Status",
+  "Normal status for an actual product",
+  "Central heating pump age:",
+  "Unknown",
+  "Controls:",
+  "Programmer, room thermostat and TRVs",
+  "Does the boiler have a Flue Gas Heat Recover",
+  "System (FGHRS)?",
+  "No",
+  "Is there a weather compensator?",
+  "No",
+  "Emitter:",
+  "Radiators",
+  "Emitter Temperature:",
+  "Unknown",
+  "Secondary Heating System",
+  "Secondary Fuel",
+  "No Secondary Heating",
+  "Water Heating & Cylinder",
+  "Water Heating Type:",
+  "Regular",
+  "Water Heating System:",
+  "From main heating 1",
+  "Cylinder Size:",
+  "No Cylinder",
+  "Ventilation",
+  "Ventilation type:",
+  "Natural",
+  "Has fixed air conditioning?",
+  "No",
+  "Number of open flues:",
+  "0",
+  "Number of closed flues:",
+  "0",
+  "Number of boiler flues:",
+  "1",
+  "Page 12",
+  "",
+  "Number of other flues:",
+  "0",
+  "Number of extract fans:",
+  "2",
+  "Number of passive vents:",
+  "1",
+  "Number of flueless gas fires:",
+  "0",
+  "Pressure test:",
+  "No test",
+  "Is there a draught lobby?",
+  "Yes",
+  "Conservatories",
+  "Is there conservatory?",
+  "No conservatory",
+  "Renewables",
+  "Wind Turbines",
+  "Has wind turbines?",
+  "No",
+  "Solar hot water",
+  "Has solar hot water?",
+  "No",
+  "Photovoltaics",
+  "Has photovoltaic array?",
+  "No",
+  "Number of PV batteries:",
+  "None",
+  "Hydro",
+  "Is the dwelling connected to Hydro?",
+  "No",
+  "Room Count Elements",
+  "Number of habitable rooms?",
+  "3",
+  "Are any of these rooms unheated?",
+  "No",
+  "Number of external doors?",
+  "1",
+  "Number of insulated external doors?",
+  "0",
+  "Number of draughtproofed external doors?",
+  "1",
+  "Number of open chimneys?",
+  "0",
+  "Number of blocked chimneys?",
+  "0",
+  "Number of fixed incandescent bulbs:",
+  "7",
+  "Is the exact number of LED and CFL bulbs known?",
+  "Yes",
+  "Number of fixed LED bulbs:",
+  "7",
+  "Number of fixed CFL bulbs:",
+  "0",
+  "Are there any waste water heat recovery systems?",
+  "None",
+  "Number of baths:",
+  "1",
+  "How many special features are there at the",
+  "property?",
+  "0",
+  "Customer Response",
+  "Customer present?",
+  "Yes",
+  "Page 13",
+  "",
+  "Customer willing to answer satisfaction survey?",
+  "No",
+  "Addendum + Related Party Disclosure",
+  "Addendum",
+  "None",
+  "Related party disclosure",
+  "No related party",
+  "Photographs Required",
+  "Page 14",
+  ""
+]
\ No newline at end of file
diff --git a/backend/documents_parser/tests/test_extractor.py b/backend/documents_parser/tests/test_extractor.py
index 65ec8c23..be577f1b 100644
--- a/backend/documents_parser/tests/test_extractor.py
+++ b/backend/documents_parser/tests/test_extractor.py
@@ -66,6 +66,11 @@ def load_text_fixture_6() -> list[str]:
         return json.load(f)
 
 
+def load_text_fixture_7() -> list[str]:
+    with open(os.path.join(FIXTURES, "pashub_site_notes_7_text.json")) as f:
+        return json.load(f)
+
+
 class TestInspectionMetadata:
     def test_full_inspection_metadata(self) -> None:
         result = PasHubRdSapSiteNotesExtractor(load_text_fixture()).extract_inspection_metadata()
@@ -785,6 +790,38 @@ class TestElectricShowerExtraction:
         assert wu.showers[0].outlet_type == "Electric Shower"
 
 
+# --- fixture 7: maisonette, 2 extensions, no property photo ---
+
+
+class TestExtractNoPropertyPhoto:
+    def test_address_extracted_when_no_property_photo(self) -> None:
+        result = PasHubRdSapSiteNotesExtractor(load_text_fixture_7()).extract()
+        assert result.inspection_metadata.property_address == "Flat 3, 29 Watcombe Circus, NOTTINGHAM, NG5 2DU"
+        assert result.inspection_metadata.property_photo is False
+        assert result.general.property_type == "Maisonette"
+        assert result.general.number_of_extensions == 2
+
+
+class TestWallThicknessExtraction:
+    def _extractor(self) -> PasHubRdSapSiteNotesExtractor:
+        return PasHubRdSapSiteNotesExtractor([])
+
+    def test_numeric_value_returns_int(self) -> None:
+        assert self._extractor()._wall_thickness_in(["Wall thickness:", "310 mm"]) == 310
+
+    def test_unmeasurable_returns_none(self) -> None:
+        assert self._extractor()._wall_thickness_in(["Wall thickness:", "Unmeasurable"]) is None
+
+    def test_unmeasurable_lowercase_returns_none(self) -> None:
+        assert self._extractor()._wall_thickness_in(["Wall thickness:", "unmeasurable"]) is None
+
+    def test_unmeasurable_uppercase_returns_none(self) -> None:
+        assert self._extractor()._wall_thickness_in(["Wall thickness:", "UNMEASURABLE"]) is None
+
+    def test_missing_field_returns_none(self) -> None:
+        assert self._extractor()._wall_thickness_in([]) is None
+
+
 class TestSolidMasonryPartyWall:
     @pytest.fixture
     def bc(self) -> BuildingConstruction:
diff --git a/datatypes/epc/domain/mapper.py b/datatypes/epc/domain/mapper.py
index 1ce4c73c..054b951f 100644
--- a/datatypes/epc/domain/mapper.py
+++ b/datatypes/epc/domain/mapper.py
@@ -1581,7 +1581,7 @@ def _map_main_building_part(
         construction_age_band=_extract_age_band(main.age_range),
         wall_construction=main.walls_construction_type,
         wall_insulation_type=main.walls_insulation_type,
-        wall_thickness_measured=main.wall_thickness_mm > 0,
+        wall_thickness_measured=main.wall_thickness_mm is not None,
         party_wall_construction=main.party_wall_construction_type,
         sap_floor_dimensions=_map_floor_dimensions(measurements.main_building.floors),
         wall_thickness_mm=main.wall_thickness_mm,
@@ -1605,7 +1605,7 @@ def _map_extension_building_part(
         construction_age_band=_extract_age_band(ext_c.age_range),
         wall_construction=ext_c.walls_construction_type,
         wall_insulation_type=ext_c.walls_insulation_type,
-        wall_thickness_measured=ext_c.wall_thickness_mm > 0,
+        wall_thickness_measured=ext_c.wall_thickness_mm is not None,
         party_wall_construction=ext_c.party_wall_construction_type,
         sap_floor_dimensions=_map_floor_dimensions(ext_m.floors),
         wall_thickness_mm=ext_c.wall_thickness_mm,
diff --git a/datatypes/epc/domain/tests/test_from_site_notes.py b/datatypes/epc/domain/tests/test_from_site_notes.py
index ff25933c..ae1dbb3b 100644
--- a/datatypes/epc/domain/tests/test_from_site_notes.py
+++ b/datatypes/epc/domain/tests/test_from_site_notes.py
@@ -694,3 +694,21 @@ class TestFromSiteNotesMiscTopLevel:
     def test_photovoltaic_array(self, result: EpcPropertyData) -> None:
         # renewables.photovoltaic_array: false
         assert result.photovoltaic_array is False
+
+
+class TestUnmeasurableWallThickness:
+    """wall_thickness_mm=None in site notes → wall_thickness_measured=False in domain."""
+
+    @pytest.fixture
+    def result(self) -> EpcPropertyData:
+        survey = from_dict(
+            PasHubRdSapSiteNotes,
+            load("pashub_rdsap_site_notes_example_unmeasurable_wall.json"),
+        )
+        return EpcPropertyDataMapper.from_site_notes(survey)
+
+    def test_wall_thickness_measured_is_false(self, result: EpcPropertyData) -> None:
+        assert result.sap_building_parts[0].wall_thickness_measured is False
+
+    def test_wall_thickness_mm_is_none(self, result: EpcPropertyData) -> None:
+        assert result.sap_building_parts[0].wall_thickness_mm is None
diff --git a/datatypes/epc/surveys/pashub_rdsap_site_notes.py b/datatypes/epc/surveys/pashub_rdsap_site_notes.py
index 73a58aa6..583eb228 100644
--- a/datatypes/epc/surveys/pashub_rdsap_site_notes.py
+++ b/datatypes/epc/surveys/pashub_rdsap_site_notes.py
@@ -44,7 +44,7 @@ class MainBuildingConstruction:
     walls_insulation_type: str
     thermal_conductivity_of_wall_insulation: str
     wall_u_value_known: bool
-    wall_thickness_mm: int
+    wall_thickness_mm: Optional[int]
     party_wall_construction_type: str
     filled_cavity_indicators: Optional[str] = None
 
@@ -59,7 +59,7 @@ class ExtensionConstruction:
     walls_insulation_type: str
     thermal_conductivity_of_wall_insulation: str
     wall_u_value_known: bool
-    wall_thickness_mm: int
+    wall_thickness_mm: Optional[int]
     party_wall_construction_type: str
     filled_cavity_indicators: Optional[str] = None
 
diff --git a/datatypes/epc/surveys/tests/fixtures/pashub_rdsap_site_notes_example_unmeasurable_wall.json b/datatypes/epc/surveys/tests/fixtures/pashub_rdsap_site_notes_example_unmeasurable_wall.json
new file mode 100644
index 00000000..261160f4
--- /dev/null
+++ b/datatypes/epc/surveys/tests/fixtures/pashub_rdsap_site_notes_example_unmeasurable_wall.json
@@ -0,0 +1,190 @@
+{
+  "inspection_metadata": {
+    "inspection_surveyor": "test",
+    "email_address": "test@test.com",
+    "report_reference": "49D422A9-0779-44DD-9665-464D35DFF1A8",
+    "created_on": "2026-03-31",
+    "date_of_inspection": "2026-03-31",
+    "property_address": "1, Test Street, Test Town, Test County, TE1 1ST"
+  },
+  "general": {
+    "epc_checked_before_assessment": true,
+    "epc_exists_at_point_of_assessment": false,
+    "inspection_date": "2026-03-31",
+    "transaction_type": "None of the Above",
+    "tenure": "Rented Social",
+    "property_type": "House",
+    "detachment_type": "Mid-terrace",
+    "number_of_storeys": 2,
+    "terrain_type": "Suburban",
+    "number_of_extensions": 0,
+    "electricity_smart_meter": true,
+    "electric_meter_type": "Single",
+    "dwelling_export_capable": true,
+    "mains_gas_available": true,
+    "gas_smart_meter": true,
+    "gas_meter_accessible": true,
+    "measurements_location": "Internal"
+  },
+  "building_construction": {
+    "main_building": {
+      "age_range": "I: 1996 - 2002",
+      "age_indicators": "local knowledge",
+      "walls_construction_type": "Cavity",
+      "cavity_construction_indicators": "stretcher bond",
+      "walls_insulation_type": "As built",
+      "thermal_conductivity_of_wall_insulation": "Unknown",
+      "wall_u_value_known": false,
+      "wall_thickness_mm": null,
+      "party_wall_construction_type": "Cavity Masonry, Unfilled"
+    },
+    "floor": {
+      "floor_type": "Ground Floor",
+      "floor_construction": "Suspended, not timber",
+      "floor_insulation_type": "As Built",
+      "floor_u_value_known": false
+    }
+  },
+  "building_measurements": {
+    "main_building": {
+      "floors": [
+        {
+          "name": "Floor 1",
+          "area_m2": 24.78,
+          "height_m": 2.37,
+          "heat_loss_perimeter_m": 14.21,
+          "pwl_m": 6.15
+        },
+        {
+          "name": "Floor 0",
+          "area_m2": 24.78,
+          "height_m": 2.35,
+          "heat_loss_perimeter_m": 14.21,
+          "pwl_m": 6.15
+        }
+      ]
+    }
+  },
+  "roof_space": {
+    "main_building": {
+      "construction_type": "Pitched roof (Slates or tiles), Access to loft",
+      "insulation_at": "Joists",
+      "roof_u_value_known": false,
+      "insulation_thickness_mm": 100,
+      "cavity_wall_construction_indicators": "No indicator of construction visible",
+      "rooms_in_roof": false
+    }
+  },
+  "windows": [
+    {
+      "id": 1,
+      "location": "Main Building",
+      "wall_type": "External wall",
+      "glazing_type": "Double glazing, Unknown install date",
+      "window_type": "Window",
+      "frame_type": "Wooden or PVC",
+      "glazing_gap": "16 mm or more",
+      "draught_proofed": true,
+      "permanent_shutters": false,
+      "height_m": 1.36,
+      "width_m": 1.0,
+      "orientation": "South East"
+    }
+  ],
+  "heating_and_hot_water": {
+    "main_heating": {
+      "selection_method": "PCDF Search",
+      "system_type": "Boiler with radiators or underfloor heating",
+      "product_id": 18400,
+      "manufacturer": "Vaillant",
+      "model": "ecoFIT sustain 415",
+      "orig_manufacturer": "Vaillant",
+      "fuel": "Mains gas",
+      "summer_efficiency": 0,
+      "type": "Regular",
+      "condensing": true,
+      "year": "2018 - current",
+      "mount": "Wall",
+      "open_flue": "Room-sealed",
+      "fan_assist": true,
+      "status": "Normal status for an actual product",
+      "central_heating_pump_age": "Unknown",
+      "controls": "Programmer, room thermostat and TRVs",
+      "flue_gas_heat_recovery_system": false,
+      "weather_compensator": false,
+      "emitter": "Radiators",
+      "emitter_temperature": "Unknown"
+    },
+    "secondary_heating": {
+      "secondary_fuel": "No Secondary Heating"
+    },
+    "water_heating": {
+      "type": "Regular",
+      "system": "From main heating 1",
+      "cylinder_size": "Normal (90-130 litres)",
+      "cylinder_measured_heat_loss": "Not known",
+      "insulation_type": "Factory fitted",
+      "insulation_thickness_mm": 12,
+      "has_thermostat": true
+    }
+  },
+  "ventilation": {
+    "ventilation_type": "Natural",
+    "has_fixed_air_conditioning": false,
+    "number_of_open_flues": 0,
+    "number_of_closed_flues": 0,
+    "number_of_boiler_flues": 0,
+    "number_of_other_flues": 0,
+    "number_of_extract_fans": 2,
+    "number_of_passive_vents": 0,
+    "number_of_flueless_gas_fires": 0,
+    "pressure_test": "No test",
+    "draught_lobby": false
+  },
+  "conservatories": {
+    "has_conservatory": false
+  },
+  "renewables": {
+    "wind_turbines": false,
+    "solar_hot_water": false,
+    "photovoltaic_array": false,
+    "number_of_pv_batteries": 0,
+    "hydro": false
+  },
+  "room_count_elements": {
+    "number_of_habitable_rooms": 2,
+    "any_unheated_rooms": true,
+    "number_of_heated_rooms": 0,
+    "number_of_external_doors": 2,
+    "number_of_insulated_external_doors": 0,
+    "number_of_draughtproofed_external_doors": 2,
+    "number_of_open_chimneys": 0,
+    "number_of_blocked_chimneys": 0,
+    "number_of_fixed_incandescent_bulbs": 0,
+    "exact_led_cfl_count_known": true,
+    "number_of_fixed_led_bulbs": 5,
+    "number_of_fixed_cfl_bulbs": 4,
+    "waste_water_heat_recovery": "None"
+  },
+  "water_use": {
+    "number_of_baths": 1,
+    "number_of_special_features": 0,
+    "showers": [
+      {
+        "id": 1,
+        "outlet_type": "Non-Electric Shower"
+      }
+    ]
+  },
+  "customer_response": {
+    "customer_present": true,
+    "willing_to_answer_satisfaction_survey": false
+  },
+  "addendum": {
+    "addendum": "None",
+    "related_party_disclosure": "No related party",
+    "hard_to_treat_cavity_access_issues": false,
+    "hard_to_treat_cavity_high_exposure": false,
+    "hard_to_treat_cavity_narrow_cavities": false
+  }
+}