Internal services
Inside the building, the main challenge is heat transfer and (on cold services) condensation. A standard foil-faced mineral wool or phenolic insulation is usually enough.
External services
Outside, the insulation faces rain, UV, wind and physical contact. It needs a weatherproof finish — typically aluminium cladding, PIB, Proclad, Klasse Wraptec or Klasseclad — to protect the insulation underneath.
Why this matters at procurement
External insulation without weatherproofing fails quickly. If the M&E spec doesn't call out the finish, ask for it before order — it's much cheaper to install at the start than retrofit later.