diff --git a/backend/ecmk_fetcher/xml_processor.py b/backend/ecmk_fetcher/xml_processor.py
index 03f435f5..dd999095 100644
--- a/backend/ecmk_fetcher/xml_processor.py
+++ b/backend/ecmk_fetcher/xml_processor.py
@@ -1,8 +1,10 @@
-from typing import Any, List, Optional, TypedDict
+import xml.etree.ElementTree as ET
+from typing import List, Optional, TypedDict
 
 from etl.xml_survey_extraction.XmlParser import PROPERTY_TYPE_LOOKUP
 
 
+# This file should ultimately live somewhere different, probably
 class Floor(TypedDict):
     area_m2: float
     height_m: float
@@ -28,8 +30,143 @@ class SapPropertyDetails(TypedDict):
     building_parts: List[BuildingPart]
 
 
-# This file should ultimately live somewhere different, probably
-def parse_rdsap(
-    xml_string: str,
-) -> SapPropertyDetails:
-    raise NotImplementedError
+def _get_namespace(tag: str) -> str:
+    return tag.split("}")[0].strip("{")
+
+
+def _require_text(value: Optional[str], field: str) -> str:
+    if value is None:
+        raise ValueError(f"Missing required field: {field}")
+    return value
+
+
+def _parse_float(value: Optional[str], field: str) -> float:
+    if value is None:
+        raise ValueError(f"Missing float field: {field}")
+    return float(value)
+
+
+def _parse_int(value: Optional[str], field: str) -> int:
+    if value is None:
+        raise ValueError(f"Missing int field: {field}")
+    return int(value)
+
+
+def _parse_thickness_mm(value: Optional[str]) -> Optional[float]:
+    if value is None:
+        return None
+    return float(value.replace("mm", "").strip())
+
+
+def parse_rdsap(xml_string: str) -> SapPropertyDetails:
+    root = ET.fromstring(xml_string)
+
+    ns_uri: str = _get_namespace(root.tag)
+    ns: dict[str, str] = {"r": ns_uri}
+
+    # --- Address ---
+    addr_elem = root.find(".//r:Address", ns)
+    if addr_elem is None:
+        raise ValueError("Address element not found")
+
+    address_parts: List[str] = [
+        addr_elem.findtext("r:Address-Line-1", default="", namespaces=ns),
+        addr_elem.findtext("r:Address-Line-2", default="", namespaces=ns),
+        addr_elem.findtext("r:Post-Town", default="", namespaces=ns),
+        addr_elem.findtext("r:Postcode", default="", namespaces=ns),
+    ]
+
+    address: str = ", ".join(part for part in address_parts if part)
+
+    # --- Property Type ---
+    prop_type_text = root.findtext(".//r:Property-Type", namespaces=ns)
+    prop_type_code: str = str(_parse_int(prop_type_text, "Property-Type"))
+    property_type: str = PROPERTY_TYPE_LOOKUP[prop_type_code]
+
+    # --- Building Parts ---
+    building_parts: List[BuildingPart] = []
+
+    for bp in root.findall(".//r:SAP-Building-Part", ns):
+
+        identifier_text = bp.findtext("r:Identifier", namespaces=ns)
+        identifier: str = _require_text(identifier_text, "Identifier")
+
+        # Floors
+        floors: List[Floor] = []
+
+        for f in bp.findall(".//r:SAP-Floor-Dimension", ns):
+
+            area = _parse_float(
+                f.findtext("r:Total-Floor-Area", namespaces=ns),
+                "Total-Floor-Area",
+            )
+
+            height = _parse_float(
+                f.findtext("r:Room-Height", namespaces=ns),
+                "Room-Height",
+            )
+
+            heat_loss = _parse_float(
+                f.findtext("r:Heat-Loss-Perimeter", namespaces=ns),
+                "Heat-Loss-Perimeter",
+            )
+
+            party_wall = _parse_float(
+                f.findtext("r:Party-Wall-Length", namespaces=ns),
+                "Party-Wall-Length",
+            )
+
+            floor: Floor = {
+                "area_m2": area,
+                "height_m": height,
+                "heat_loss_perimeter_m": heat_loss,
+                "party_wall_length_m": party_wall,
+            }
+
+            floors.append(floor)
+
+        # Roof (optional)
+        roof: Optional[Roof] = None
+
+        roof_construction_text = bp.findtext("r:Roof-Construction", namespaces=ns)
+        roof_ins_loc_text = bp.findtext("r:Roof-Insulation-Location", namespaces=ns)
+        roof_thickness_text = bp.findtext("r:Roof-Insulation-Thickness", namespaces=ns)
+
+        if (
+            roof_construction_text is not None
+            or roof_ins_loc_text is not None
+            or roof_thickness_text is not None
+        ):
+            roof_dict: Roof = {}
+
+            if roof_construction_text is not None:
+                roof_dict["construction"] = _parse_int(
+                    roof_construction_text, "Roof-Construction"
+                )
+
+            if roof_ins_loc_text is not None:
+                roof_dict["insulation_location"] = _parse_int(
+                    roof_ins_loc_text, "Roof-Insulation-Location"
+                )
+
+            thickness = _parse_thickness_mm(roof_thickness_text)
+            if thickness is not None:
+                roof_dict["insulation_thickness_mm"] = thickness
+
+            roof = roof_dict
+
+        building_part: BuildingPart = {
+            "identifier": identifier,
+            "floors": floors,
+            "roof": roof,
+        }
+
+        building_parts.append(building_part)
+
+    result: SapPropertyDetails = {
+        "address": address,
+        "property_type": property_type,
+        "building_parts": building_parts,
+    }
+
+    return result