diff --git a/recommendations/WallRecommendations.py b/recommendations/WallRecommendations.py
index 935ff96c..818e7e98 100644
--- a/recommendations/WallRecommendations.py
+++ b/recommendations/WallRecommendations.py
@@ -142,14 +142,19 @@ class WallRecommendations(Definitions):
         material will give us the best U-value.
 
         We check for diminishing returns, however this function does not check for meeting building
-        part L regulations right now
+        Part L regulations right now. This is because Part L is less stringent for cavity walls
+
+        Width of a cavity:
+        There are various sources online that suggest the width of a cavity wall is around 50mm. The retrofit course
+        indicates that most cavities are 50-75mm. Many sources online indicate that 50mm is the standard figure
+        therefore we'll use 50mm as the base assumption
+
         :param u_value: u_value of the starting wall
-        :return:
         """
 
         cavity_wall_fills = [m for m in self.materials if m["type"] == "cavity_wall_insulation"]
-        # TODO: Check this and also check the methodology
-        cavity_width = 125
+
+        cavity_width = 50
         # Test the different fill options
         lowest_selected_u_value = None
         recommendations = []