http://www.legislation.gov.uk/nia/2011/12/section/15Caravans Act (Northern Ireland) 2011An Act to amend the law relating to caravans and caravan sites.texttext/xmlenStatute Law Database2017-11-30Expert Participation2016-10-31 PART 4 151In this Act “caravan” means any structure designed or adapted for human habitation which is capable of being moved from one place to another (whether by being towed, or by being transported on a motor vehicle or trailer) and any motor vehicle so designed or adapted, but does not include—aany railway rolling stock which is for the time being on rails forming part of a railway system for the time being in use as such;bany tent; orca structure—iwhich falls within subsection (2); andiiany dimensions of which, when the structure is assembled, exceed a limit specified in subsection (3).2A structure falls within this subsection if it is—acomposed of not more than two sections separately constructed and designed to be assembled on a site by means of bolts, clamps or other devices; andbwhen assembled, physically capable of being moved by road from one place to another (whether by being towed, or by being transported on a motor vehicle or trailer).3The limits referred to in subsection (1)(c)(ii) are—alength (exclusive of any drawbar): 20 metres;bwidth: 6.8 metres;coverall height of living accommodation (measured internally from the floor at the lowest level to the ceiling at the highest level): 3.05 metres.4A structure which falls within subsection (2) is not excluded from being a caravan by reason only that when assembled it cannot lawfully be moved from one place to another on a road.5The Department of the Environment may by order, after consultation with such persons or bodies as appear to it to be concerned, substitute for any figure mentioned in subsection (3) such other figure as may be specified in the order.6An order under subsection (5) is subject to negative resolution.S. 15(5): transfer of functions (8.5.2016) by The Departments (Transfer of Functions) Order (Northern Ireland) 2016 (S.R. 2016/76), art. 1(2), Sch. 5 Pt. 2 (with art. 9(2))