Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 75·5.20
Guarding of flue pipes and factory-made chimneys
Flue pipes and factory-made chimneys must be guarded where they present a burn hazard that is not immediately apparent or where they could be at risk of damage.
A flue pipe flue and factory-made chimney should be guarded where –
(a) they present a burn hazard to people that is not immediately apparent; or
(b) they could be at risk of damage.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/Technical Booklet L - Combustion Appliances and Fuel Storage Systems.pdf