NEED HELP with Planning or Building Regulations?

In most instances, Planning & Building Regulations do not apply to Garden Outbuildings:

Planning Permission

Outbuildings are generally considered to be permitted development under Class E, and do not need Planning Permission, subject to a number of limits and conditions.

The most important factors are:

1) That the building is no higher than 2.5m from the bottom of the building to the top of the roof

2) That you do not take up more than 50% of your garden area with this or any other buildings

3) It is not to be used for living or sleeping accomodation

NOTE: All our buildings are manufactured to meet the 2.5m height Planning restriction.

In more detail -

DEFINITION of 'Permitted Development':

'The provision of any outbuilding within the curtilage of the dwelling for a purpose incidental to the enjoyment of the dwelling, or the maintenance, improvement or alteration of such building or enclosure'.

Essentially, this means that so long as the purpose of the development is incidental to the enjoyment of the dwelling it will be classed as Permitted Development except in the following circumstances:

  • You are not allowed an outbuilding which projects forward of the front elevation of the original house.
  • Any outbuilding must be single storey and have a maximum eaves height of no more than 2.5 metres. The maximum overall height must not be more than 4 metres if a dual pitched roof is specified, or 3 metres for any other roof
  • If the outbuilding is to be positioned within 2 metres of the property boundary, no part of  it shall exceed 2.5 metres in height. So below 2.5m height it can be positioned as close to the boundary as is practical.
  • No balconies or verandas are allowed on an outbuilding without Planning Permission.
  • Decking or other raised platforms can be fitted around the outbuilding, but only up to a maximum height of  300mm.
  • Any outbuilding must not be used as self-contained living accommodation, and must not have a TV, or Satellite type of aerial. Planning Permission will be required in these cases.
  • Outbuildings and other additions must not take up more than half the area of land around the "original house". “Original house” means the house as it was first built, or as it was on 1st July 1948 (If built before that date). Extensions, timber sheds and all other outbuildings must be included when calculating this limit. Although you may not have built an extension, the previous owner could have done, and this needs to be included in calculating the overall limit.
  • On designated land, (areas of Outstanding Natural Beauty, National Parks, the Broads, Conservation Areas and World Heritage Sites), the maximum size of an outbuilding will be limited to 10 square metres and must be 20m from any wall of the house.
  • On designated land (AONB etc), outbuildings at the side of the house will require planning permission.
  • If the original building has Listed Status, all outbuildings will need full planning permission.


This guidance applies to planning regulations in England only. Policy for Scotland and Wales may differ slightly please check with your Local Authority.

In addition, although many of our Garden Rooms are designed to be below the 2.5m maximum height allowance for Permitted Development, allowing buildings to be placed right up against a boundary, please note that we usually need a minimum of 400mm clearance all around our buildings to facilitate assembly and Health and Safety precautions.

Building Regulations

In brief:

1) Building Regulations do not usually apply unless you want to sleep in it

2) Under 15m2 internal floor area can be installed close to any rear boundary

3) Over 15m2 and up to 30m2 needs to be a minimum 1m from any boundary

If you want to put up small detached buildings such as a garden shed, garden room or summerhouse in your garden, Building Regulations (except Part P for Electrical works) will not normally apply if the floor area of the building is less than 15 square metres INTERNALLY and contains NO sleeping accommodation.

If the INTERNAL floor area of the building is between 15 square metres and 30 square metres, you will not normally be required to apply for building regulations approval, providing that the building contains NO sleeping accommodation, and is either at least one metre from any boundary, or it is constructed of substantially non-combustible materials.

Complying with Building Regulations

Therefore in general, Garden Buildings do not need to comply with Building Regulations (other than Part P for Electrical works).  However, at MODULAR LIFE CABIN & TINY (MOBILE) HOUSE we believe it is good practice to work to Part A of the Regulations, to provide assurance to our customers that our buildings are not only BUILT TO LAST but are also structurally safe and sound.

Part A of the Regulations for structural integrity is fully complied with, ensuring that the building is constructed so that combined dead loads (weight of structural elements), imposed loads (snow, maintenance activities, etc) and wind loads are accounted for.  Issues addressed cover elements such as the size and bearing of roof timbers relative to the unsupported roof span per guidance issued by NHBC and TRADA.

Part L (does not apply to buildings under 50m2 internal floor area per Regulation 21) takes account of the insulation qualities of walls, roof, floor, doors and windows, and new Building Regulations introduced in April 2014 impose stricter fabric U-Values for England and Wales of:

ENGLAND:  Wall 0.18,  Floor 0.13,  Roof 0.13.

WALES:  Wall 0.21,  Floor 0.18,  Roof 0.15.

The rules for Scotland known as Section 6 Regulations will also change in 2015.

We are constantly reviewing our specifications to ensure that all our Garden Rooms offer the best compromise between cost and operational comfort. Due to the ever increasing costs of complying with the demands of the Kyoto agreement for increased levels of insulation, we have no option but to offer to meet the above targets at an additional cost over and above our standard pricing.

As a Guide: The estimated usage of electricity for heating a 12sq metre MODULAR LIFE CABIN & TINY (MOBILE) HOUSE Garden Room equates to around £100 per year at 2015 prices.

Part P In the case of Garden Buildings Part P applies and any work is notifiable to the Local Authority.  Work can be self-certified by an Electrical Installer who is registered as a competent person using a BS7671 electrical installation certificate for every job they undertake, with a copy given to the householder. This is supplied by MODULAR LIFE CABIN & TINY (MOBILE) HOUSE where we are contracted to do this work.

Consequently, Part P for Electrical installations is complied with in so far as MODULAR LIFE CABIN & TINY (MOBILE) HOUSE is contracted or otherwise to carry-out either internal or external works, or both as the case may be.

Please note:

Our standard Garden Buildings are electrically equipped and wired internally only. Although we are happy to quote for the installation of an armoured cable from the house to the Studio as required, it is not included in our standard Garden Room prices due to the many on-site variables such as: distance from the main house to the Garden Room; footpaths, patios, driveways and obstacles in the way etc. Sometimes it is more beneficial for our clients to engage a local Electrical Contractor, rather than pay the higher costs which we would need to charge due to the distance travelling to site by our own Electrical specialist. All supply cables need to be Armoured, sized to account for Voltage drop and if buried, must be to a sufficient depth to avoid future harm.

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