Under section 4(1)(h) of the Planning and Development Act 2000, development consisting of the carrying out of works for the maintenance, improvement or other alteration of any structure is exempted development only if the works affect only the interior of the structure or do not materially affect the external appearance of the structure so as to render the appearance inconsistent with the character of the structure or of neighbouring structures. It is a matter for each planning authority to determine whether planning permission is required on a case by case basis.
It is not proposed to amend the planning and development regulations 2001 to introduce a specific exception for smoking shelters.