diff --git a/domain/modelling/generators/roof_recommendation.py b/domain/modelling/generators/roof_recommendation.py
index f20a5103a..5d2c1cd0c 100644
--- a/domain/modelling/generators/roof_recommendation.py
+++ b/domain/modelling/generators/roof_recommendation.py
@@ -1,13 +1,15 @@
 """The roof Recommendation Generator.
 
 Dispatches the MAIN roof to its single applicable insulation Measure by roof
-type (ADR-0021): a sloping ceiling (rafters, 100 mm), or — the fallback — a
-loft / thatched / unlodged pitched roof (joists, 300 mm); a no-access roof gets
-nothing. Each emits one "Roof" Recommendation whose Option carries the
+type (ADR-0021): a sloping or vaulted ceiling (rafters, 100 mm), a flat roof
+(200 mm), or — the fallback — a loft / thatched / unlodged pitched roof
+(joists, 300 mm); a no-access roof gets nothing. The pitched branches resolve
+a lodged sentinel thickness ("ND" / nothing) to the age band's as-built state
+(ADR-0047). Each emits one "Roof" Recommendation whose Option carries the
 insulation Simulation Overlay (raising `roof_insulation_thickness`) and a priced
 Cost (roof area x the Product's fully-loaded unit cost, with its contingency).
-Flat-roof and room-in-roof branches land in later slices. No scoring, no
-persistence — impact is produced later by scoring (ADR-0016).
+The room-in-roof branch lands in a later slice. No scoring, no persistence —
+impact is produced later by scoring (ADR-0016).
 """
 
 from typing import Final, Optional, Union
@@ -24,9 +26,6 @@ from repositories.product.product_repository import ProductRepository
 
 _LOFT_MEASURE_TYPE = MeasureType.LOFT_INSULATION
 _SLOPING_CEILING_MEASURE_TYPE = MeasureType.SLOPING_CEILING_INSULATION
-# RdSAP 10 Table 16: 0 mm lodged roof insulation is an uninsulated loft. The
-# Elmhurst mapper resolves "As Built" to 0 for pitched/sloping/loft roofs.
-_ROOF_UNINSULATED_MM = 0
 # Recommended loft-insulation depth (mm). Elmhurst re-lodges a loft-insulation
 # measure at 300 mm; pinning the before→after cascade (000490/001431) requires
 # the overlay to match that depth exactly (see test_elmhurst_cascade_pins).