diff --git a/repositories/property/landlord_override_overlays.py b/repositories/property/landlord_override_overlays.py
index b8e9199d..3eff5213 100644
--- a/repositories/property/landlord_override_overlays.py
+++ b/repositories/property/landlord_override_overlays.py
@@ -3,9 +3,22 @@
 The boundary between the faithful `property_overrides` read model
 (`ResolvedPropertyOverrides`, value-space) and the domain overlay surface
 (`EpcSimulation`). Lives in `repositories/` because it consumes a repository
-type — `domain/` never imports `repositories/`. Per-component and partial: an
-override produces an overlay only where a component mapping exists and resolves
-(the tracer covers `wall_type`); everything else is left to the lodged EPC.
+type — `domain/` never imports `repositories/`.
+
+Per-component and partial — an override produces an overlay only where a
+component mapping exists and the value resolves; anything else is left to the
+lodged EPC. All four `override_component`s are mapped:
+
+* `wall_type`  → fabric overlay (`wall_construction` + `wall_insulation_type`)
+* `roof_type`  → fabric overlay (`roof_insulation_thickness`, loft-depth family)
+* `property_type` / `built_form_type` → whole-dwelling categorical correction
+
+Two value families deliberately resolve to *no* overlay rather than a guess: the
+`"(assumed) insulated"` / `"partial insulation (assumed)"` wall states (RdSAP
+infers their U-value from the build-era age band, so there is no single
+`wall_insulation_type` code for them — they need Elmhurst validation, ADR-0032),
+and `"Unknown"` categorical values. Roofs with no clean loft depth (flat,
+room-in-roof, "another premises above") likewise produce no overlay.
 """
 
 from __future__ import annotations