As of 2019, there is a much more complete version of this guide on the Century Wood website now.
Links to useful pages and documents relevant to putting up huts, sheds, cabins, and chalets:
England, Wales, and Scotland
The first schedule of the Caravan Sites and Control of Development Act 1960 has useful exemptions where caravans can be used for accommodation without a site license, in sections 3 (Use of holdings of five acres or more in certain circumstances), 7 (Agricultural workers), 8 (Forestry workers), 9 (Building and engineering sites). Part I section 29 of the main body of the act defines a caravan as “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)”, which includes portacabins, converted shipping containers, and some rigid lodges and camping pods as well as conventional static or mobile caravans.
Discussion of time limits for the prior notification process in agricultural (and forestry) permitted development in the GPDO, which can allow building to go ahead by default if local planning authorities do not process notifications within 28 days.
England and Wales
The Building Regulations for England include an exemption (Class 6) for isolated single-storey buildings less than 30 square metres in floor area which contain no sleeping accommodation.
Schedule 2 of the 2015 General Permitted Development Order which grants planning permission for certain activities without going through a full planning application to the local council, and is identical to the 1995 GPDO for our purposes. Parts 4 (Temporary Buildings and Uses), 5 (Caravan sites and recreational campsites), 6 (Agricultural and forestry) are of particular interest. Part 6, Class E prohibits the construction of forestry buildings to provide “dwellings” but intermittently staying in a building does not make it a dwelling (House of Lords, Uratemp vs Collins, 2001; Appeal Court, Moore vs Secretary of State, 2012).
Summary of the Supreme Court decision in the Beesley case of building a house disguised as a hay barn: http://www.localgovernmentlawyer.co.uk/index.php?option=com_content&view=article&id=6310%3Asupreme-court-backs-council-in-dispute-over-house-disguised-as-a-barn&catid=56%3Alitigation-articles
Schedule 2 of the 1995 General Permitted Development Order is still in force in Wales, with separate Agricultural (6) and Forestry (7) parts but the same wording as the 2015 GPDO now in force in England.
Scottish time limits on planning enforcement by councils: http://www.legislation.gov.uk/ukpga/1997/8/section/124 and certificates of lawful development after the time limits have passed to prove everything is ok: http://www.legislation.gov.uk/ukpga/1997/8/section/150
The enforcement notice appeal ENA-270-60 from April 2009 to the Scottish planning reporter rules that a Mongolian tent (a yurt) can be kept on agricultural land and used as a temporary shelter while doing agricultural work. The reporter made the fine distinction that the yurt was a building but it was not the result of building work: “a yurt is erected (or assembled) and not built”. Consequently, it could be occupied as a building for agricultural purposes, but planning permission or even the prior notification process was not required to put it up. The principle should apply to other structures which can be put up without “operations normally undertaken by a person carrying on business as a builder” as section 26(4)(d) of the Town and Country Planning (Scotland) Act 1997 puts it (as does the corresponding wording for England and Wales.)
The 2014 Scottish Planning Policy is not legally binding but is a statement of what local authorities are expected to put in their local plans, and how ministers and their planning inspectors are likely to rule if local authority planning refusals are appealed. Section 79 says “Plans should set out a spatial strategy which … where appropriate, sets out policies and proposals for leisure accommodation, such as holiday units, caravans, and huts”. The glossary defines huts as “A simple building used intermittently as recreational accommodation (ie. not a principal residence); having an internal floor area of no more than 30m2; constructed from low impact materials; generally not connected to mains water, electricity or sewerage; and built in such a way that it is removable with little or no trace at the end of its life. Huts may be built singly or in groups.”
The Building Regulations for Scotland include a more restrictive exemption than in England and Wales, exempting isolated single-storey buildings less than 8 square metres in area and without “a fixed combustion appliance installation or sanitary facility”. However after lobbying by the Thousand Huts Campaign, the Scottish Government plans to introduce an exemption for huts in 2017, as the campaign explains.