diff --git a/model_data/recommendations/WallRecommendations.py b/model_data/recommendations/WallRecommendations.py
index 08b2c16f..f48b51cb 100644
--- a/model_data/recommendations/WallRecommendations.py
+++ b/model_data/recommendations/WallRecommendations.py
@@ -10,13 +10,15 @@ external_wall_insulation_parts = [
         # -slab-ewi-render-fire/
         "type": "external_wall_insulation",
         "description": "Mineral Wool External Wall Insulation",
-        "depths": [],
+        "depths": [30, 50, 70, 80, 90, 100],
         "depth_unit": "mm",
         "cost": None,
+        "cost_unit": None,
         # The u-value here is just a placehoder for now and we probably want to have multiple
         # options for internal wall insulation (e.g. 50mm, 100mm, 150mm), with different material types
         # and costs
-        "u_value": None
+        "r_value_per_mm": 0.0278,
+        "r_value_unit": "m2K/W"
     },
     {
         "type": "external_wall_insulation",
@@ -198,23 +200,38 @@ class WallRecommendations:
         return u_value_uplift, new_u_value
 
     @staticmethod
-    def convert_r_value_to_mm(r_value_wmk):
+    def rvalue_per_mm(total_r_value: float, thickness_mm: float) -> float:
+        """Return R-value per mm.
+
+        Parameters
+        ----------
+        total_r_value : float
+            Total R-value (in m2K/W).
+        thickness_mm : float
+            Thickness of the material in mm.
+
+        Returns
+        -------
+        float
+            R-value per mm.
         """
-        Converts an R-value from units of W/m·K to per millimeter (mm).
+        return total_r_value / thickness_mm
 
-        :param r_value_wmk: R-value in units of W/m·K.
-        :type r_value_wmk: float
-
-        :return: Converted R-value per mm.
-        :rtype: float
-
-        :notes:
-            - This function utilizes the 'pint' library to handle units and perform the conversion.
+    @staticmethod
+    def r_value_per_mm_to_u_value(depth_mm: int, r_value_per_mm: float):
         """
+        Converts R-value per mm to U-value in W/m²K.
 
-        ureg = pint.UnitRegistry()
+        Parameters
+        ----------
+        depth_mm : int
+            Depth of the material in mm.
+        r_value_per_mm : float
+            R-value per mm.
 
-        r_value = r_value_wmk * ureg.watt / (ureg.meter * ureg.kelvin)
-        r_value_per_mm = r_value.to(1 / ureg.millimeter)
-
-        return r_value_per_mm.magnitude
+        Returns
+        -------
+        float
+            U-value in W/m²K.
+        """
+        return 1 / (depth_mm * r_value_per_mm)