Forget moving - make the most of what you have by extending your house up, out or down...

Why move when you can improve? There are lots of reasons to extend, whether you want to create more space, add value to your home or just love the area in which you live. ‘The increasing cost and hassle of moving combined with uncertainty in the property market makes staying put an attractive choice.

Many properties have untapped potential, and renovations can make a home more enjoyable to live in as well as adding to its market value.’

Once you have dealt with planning, if you are in a hurry to start extending, you can commence work immediately after giving the local authority building control depar­­tment 48 hours’ notice. You are required to submit a ‘Building Notice’ and the required fee. Generally the Buildi­ng Notice method is more suitable for simple works where detailed draw­ings are not required, but it can be used for any project, with the exception of work to listed buildings. For most extensions it is best to make a Full Plans application. This involves submitting detailed drawings, specifications, calculations and a location plan for inspection by the local authority, together with the appli­ca­tion forms and appropriate fee. Building control has to respond within five weeks unless you agree to give them an extension to two months. A Full Plans submission allows any irregularities to be resolved before work commences. With a Building Notice, the building control officers can ask for proof of compliance at any stage, so it is essential to make sure they make all necessary inspec­tions and provide any structural calcula­tions when requested. When the project is com­pleted and inspect­ed by the local authority, a completion certifi­cate will be issued which will prove useful if the property is ever to be sold on. Application fees are set individually by each local author­ity.

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Current UK Building Regulations 

There are currently sixteen parts (sections) to the building regulations (E & W) and each is lettered as Part A to Part Q (however there is no Part I or N) accompanied by an approved document for that Part X. The approved documents usually take the form of firstly stating the legislation and then providing a number of methods or ways which are deemed to satisfy the regulations.

The building regulations do not aim to stifle innovation, and each Approved Document's introduction states this Government Aim. Compliance with the legislation is what is ultimately required and there may be many ways of complying, other than just using the ways set out in the recommended provisions within each of the approved documents. In reality, an innovative solution may be hard to validate, and for most building work the tendency is to take the regulations literally.

For example, bathroom manufacturers produce a 'Doc M Pack' for disabled toilets, which reproduces exactly the diagram in Part M, and most public disabled toilets are now designed around this layout.

Many manufactured products have agrément certificates issued by the British Board of Agrément (BBA, a construction products certification service),[2] certifying compliance with relevant standards. However, the BBA and other bodies (TRADA, BRE, Exova Warrington, etc.) may be able to test and certify to "CE" harmonised EU standards. "CE" marking of all construction materials and products is now a legal requirement, since 1 July 2013.

Most of the detailed information on the Building Regulations is now available on where general public users can access simplified building regulations guidance, and professional users have a better organised version of what was on the former DCLG building regulations website, including the full versions of the Approved dDcuments and associated guidance, held on the DCLG website (now a constituent part of the website)

Part A. Structure

This Part requires buildings to be designed, constructed and altered so as to be structurally safe and robust, and also so as not to impair the structural stability of other buildings.

It stipulates design standards that should be adopted for use on all buildings and additionally gives simple design rules for most masonry and timber elements for traditional domestic buildings.

The weight of the building from the walls, furniture and people in the building will be transmitted to the ground, so as not to cause instability to the building or other buildings.

Requires buildings to be built in a way ensuring no collapse will occur disproportionately to its cause.

Ground movement such as freezing of subsoil will not impair the stability of the building.

The Party Wall, etc Act 1996 also controls walls and foundations being built near to existing buildings. However, it is "civil law" and is not enforced by Building Control Bodies.

Part B. Fire safety

The building regulations consider five aspects of fire safety in the construction of buildings:

Requirement B1 - Means of early warning of fire and adequate means of escape from the building (including emergency lighting and fire exit signage).

Requirement B2 - Control of Internally fire spread (linings)

The wall lining i.e. plaster, plasterboard or wooden boards on the walls and ceiling will resist the spread of flames and give off only reasonable levels of heat, if on fire.

Requirement B3 - Control of Internal fire spread (structure) will be maintained during a fire, and fire spread will be prevented.

Fire and smoke will be prevented from spreading to concealed spaces in a building's structure by Fire Stopping and Fire Cavity Barriers.

Requirement B4 External fire spread – The external walls and roof will resist spread of fire to walls and roofs of other buildings.

However, Not all buildings are required to have non-combustible exterior finishes.

Requirement B5 The building will be accessible for firefighters and their equipment, without delay.

Tall and Large buildings to have Fire Lifts and Fire Mains (Dry or Wet riser pipes), etc.

Alternative Means to comply

Using BS9999 : 2008 for non-residential buildings

Using BS9991 : 2015 for dwellings and other residential buildings

The use of a Fire Engineer to computer model the building layout and smoke behavior in such a building.

Building Regulation 38

This requires the designer and/or constructor to give the fire safety information (for a description of the information required – see Appendix G of approved document B) to the Responsible Person, upon completion. This is to enable a competent person to carry out a fire risk assessment.

Other fire laws (England & Wales and Scotland)

Once a building is occupied the Fire Safety Order 2005 requires a Fire Risk Assessment to be carried out, to take into account how the users are actually using the building (and any fire risks that brings to the building) and the FSO2005 requires the "Responsible Person(s)" for the building to provide and maintain "suitable and sufficient" general fire precautions. (Full citation is the Regulatory Reform (Fire Safety) Order 2005. Scotland's Fire Safety legislation is very similar and only slightly different in practical effect.

The Fire Safety Order 2005 is criminal law, and breaches of this law can result in the "Responsible Person" being jailed for up to two years and fined up to £10,000 for each offence. Corporate offences may have unlimited fines.

Enforcement is by the local fire authority. It may be necessary to exceed the recommendations of the guidance supporting Part B of Schedule 1 to Building Regulations, in order to achieve a suitable and sufficient level of fire safety required under the Fire Safety Order 2005.

Review of fire related building regulations in England, 2017

Hanover House, a residential tower block in Sheffield, with its cladding partially removed after failing fire safety tests following the Grenfell Tower fire.

Building regulations are technically under constant review by the DCLG (and are currently being urgently reviewed in light of Grenfell Tower fire). As following this fatal fire in London in June 2017, there is industry wide concern over fire safety issues with many other buildings. Inappropriate combustible material combinations have been found on a broad range of tall local authority, private, NHS, educational and housing association buildings.

Combustible materials within the external construction of the outside of tall buildings must comply with the building regulations but this guidance has sometimes been interpreted as applying only to the insulation and not to the cladding. There are concerns that fire tests may not accurately reflect real life when a building, cladding and insulation are subject to wear and tear. The DCLG has set up a weekly email newsletter for those interested in this topic.

Part C. Site preparation and resistance to contaminants and moisture

Nothing should be growing on the ground covered by the building.

Precautions must be taken to stop gases and dangerous substances from previous land use from entering the building and endangering the health and safety of occupants.

Subsoil drainage will be in place, if needed, to stop the passage of ground moisture to the interior of the building and to prevent damage to the fabric of the building.

The walls, floors and roof of the building shall prevent moisture passing to the inside of the building.

The building must have provision to prevent condensation occurring in the roof structure.

Part D. Toxic substancesSome Insulating Materials inserted into (existing) cavity walls can give off toxic fumes. Preventative measures must be taken to stop these fumes reaching occupants of the building. However now largely obsolete as injected materials are now mostly blown chopped fiber and not mixed on-site "chemical reaction" based methods.

See Part C for controls on toxic hazards from ground contaminants and/or brownfield development.

Part E. Resistance to the passage of sound

Approved Document E 2003 plus amendments 2004 should be read in conjunction with supplemental document 'Robust Details Part E - Resistance to the passage of sound'.

Separating floors and walls between domestic dwellings are required to meet a minimum sound insulation performance standard. This applies to both new 'purpose built' and converted 'material change of use' properties.

  • Purpose built – the sound insulation value for each individual airborne test should be equal to or greater than 45 dB DnTw+Ctr. Each individual impact test should be equal to or less than 62 dB LnTw.
  • Material change of use – the sound insulation value for each individual airborne test should be equal to or greater than 43 dB DnTw+Ctr. Each individual impact test should be equal to or less than 64 dB LnTw.

New internal walls and floors within dwelling-houses, flats and rooms for residential purposes, whether purpose built or formed by material change of use should achieve a minimum performance of Rw 40 dB when tested in a laboratory. Test data is to be taken from a UKAS accredited laboratory.

Pre-completion sound tests have been required since July 2003 to ensure compliance with Approved Document E, unless the robust detail  approach is adopted, see Part L below. Testing is to be undertaken by a UKAS registered test organisation or European equivalent (e.g. ANC). A list of preferred UKAS accredited companies can be found at UKAS Organisation Search. A list of preferred ANC accredited companies can be found at

Care should be taken to ensure site conditions are appropriate before testing commences to ensure tests can be completed and that the best results are achieved.

Part F. Ventilation

Standards for ventilation and air quality requirements for all buildings are included in this part of the building regulations

Due to the increasing complexity of the Regulations, ventilation strategies and system design must be considered at the earliest stages of building design.

The Building Regulations consider three ventilation types:

  • "Whole building" (formerly referred to as "background") ventilation to provide fresh air to dilute and disperse low levels of water vapour and other pollutants, usually by the provision of background ventilators or mechanical supply ventilation.
  • "Local extract" (formerly referred to as "extract") ventilation in rooms where most water vapour or concentrated pollutants are released, usually by mechanical means such as extract fans.
  • "Purge" (formerly referred to as "rapid") ventilation for the rapid dilution and removal of high concentrations of pollutants from occasional activities, usually by opening windows. The requirements for purge ventilation are set out in Appendix B of Part F1.

The performance rates for each of the "system" approaches set out in Part F are the minimum requirements needed to ensure that adequate air quality is provided for people indoors. The occupants' health could be at risk if these ventilation rates are compromised.

The performance rates do not take account of summer overheating.

Most systems may be manually or automatically controlled (with manual override).

For each system to be effective, air must be able to flow through the dwelling. The regulations make provision for this via internal door undercuts to maintain a minimum gap of 10mm above the finished floor surface. This provides a 7600mm² permanent opening when a door is closed.

There are alternative methods to achieve compliance with Part F. The following explanations are simplified versions of the most common methods of interpreting the "Systems" approach set out in the provisions section of the Regulation.

Background ventilators are now measured in equivalent area (mm² EA) which is a better measure of performance but does not directly relate to the physical size of the opening through the ventilator.

  • System 1 - Intermittent extract fans and background ventilators
  • System 2 - Passive stack ventilation and background ventilators
  • System 3 - Continuous mechanical extract and background ventilators
  • System 4 - Continuous mechanical supply and extract with heat recovery

Part G. Sanitation, hygiene and water efficiency

Adequate sanitation facilities i.e. toilet.

A house must have either a bath or shower with the ability to heat hot water.

Unvented hot water storage systems – restrictions apply to who can install the system.

Part H. Drainage and waste disposal

An adequate system to carry water used for cooking, washing, toilet, bath or shower to a sewer, cesspool or settlement tank must be in place.

A cesspool or settlement tank must be impermeable to liquids and have adequate ventilation. It must also have means of access for emptying, not harm the health of any person and not contaminate water or water supply.

An adequate system to carry rainwater away from the roof of a building e.g. guttering carrying water to a sewer.

A place to put a wheelie bin or dustbin. The place must not harm anyone's health.

Part J. Combustion appliances and fuel storage system

Must have an adequate air supply for combustion and for efficient working of a flue pipe or chimney.

Appliances shall discharge the products of combustion to the outside.

The appliance, fireplace and chimney shall reduce the risk of the building catching fire.

See Part B for general fire safety.

Part K. Protection from falling, collision and impact

Part K sets minimum standards for the safety of stairways, ramps and ladders, together with requirements for balustrading, windows, and vehicle barriers to prevent falling from floor edges, etc.

Glass and glazing safety is also covered. Also included are requirements for guarding where there is a risk of falling, pedestrian and vehicle barriers, and requirements to prevent injury from (opening) doors and windows.

Glazing that people come into contact with whilst in a building, should, if broken, break in a way unlikely to cause injury, resist impact without breaking or be shielded or protected from impact.

Buildings, other than dwellings that have transparent glazing which people come into contact with while moving around a building, must have features to make it apparent.

Windows that can be opened must be operated safely and provision made for safe accessible cleaning.

Part K also includes safety requirements relating to the use, operation, and cleaning of windows

Part K also includes safety requirements for automatic doors, barriers, shutters and gates.

Part L. Conservation of fuel and power

Approved documents L1 is specific to dwellings and L2 relates to all buildings other than dwellings.

As of 6 April 2006 (2010) (2014) split into four sections:

  • L1A New dwellings
  • L1B Existing dwellings
  • L2A New buildings other than dwellings
  • L2B Existing buildings other than dwellings

Part L controls the insulation values of building elements, the allowable area of windows, doors and other openings, air permeability of the structure, the heating efficiency of boilers and the insulation and controls for heating appliances and systems together with hot water storage and lighting efficiency. It also sets out the requirements for SAP (Standard Assessment Procedure) calculations and carbon emission targets for dwellings.

Regulation 16 requires the advertising of the SAP rating in all new dwellings, and in the EPC document.

Approved Document L1 is supported by a set of 'robust' construction details, now known as "Accredited Construction Details". which focus on way of limiting air leakage and thermal bridging in construction. By using these tried and tested details, expensive on-site testing can be avoided.

In addition to insulation requirements and limitation of openings of the building fabric, this part considers solar heating and heat gains to structures, it controls heating, mechanical ventilation and air conditioning systems, lighting efficiency, space heating controls, air permeability, solar emission, the certification, testing and commissioning of heating and ventilation systems, and requirements for energy meters.

Air permeability is measured by air tightness testing for new dwellings (based on a sampling regime), all new buildings other than dwellings and large extensions to buildings other than dwellings.

These four Approved Documents must be read in conjunction with the supplemental official and industry documents (the 'second tier' guidance documents).

Energy Performance Certificate "EPC"

All EPCs will be based on SAP 2009 calculations from 1 April 2011. It is highly unlikely that many dwellings built to Part L 2010 will be completed before 1 April 2011. However, in the event that any are, the EPC will need to be produced using SAP 2005.

Please note that all plots require a building control approval submission, and EPC regardless of how many identical properties are to be built in the same development.

Part L new requirements

Lighting, ventilation, solar heat gain and possible overheating will all impact on the potential to hit the 25% reduction target but until now have not really troubled the industry. As U-values falls (see table) and airtightness levels increases, heat loss through 'thermal bridges' becomes more significant. The new regulations give these issues more emphasis. They also require designs to avoid unwanted solar gains, leading to excessive summer temperatures. The need now exists to consider these issues at the design stage.

See also:

Part M. Access to and use of buildings

Part M requires the inclusive provision of ease of access to and circulation within all buildings, together with requirements for facilities for disabled people.

Buildings should have reasonable provision:

  • For all people to gain access and use the building.
  • Toilets provision shall be made available for all.
  • If a building has seating such as audience or spectator seating, reasonable provision should be made for people with disabilities.

The Equality Act 2010 imposed duties on service providers, schools and public bodies in relation to access for people with disabilities. However, the Part M approved document is not written as a means of ensuring compliance with these legal duties. It is written to ensure that the design of a building does not create physical barriers to a building's inclusive use, over its lifetime.

Part M of the Building Regulations relates to the 'Access to and Use of Buildings' and draws largely on the legislation covered by the Disability Discrimination Act 1995 and the Disability Discrimination (Employment) Regulations 1996.

This document is particularly relevant to new build where such properties must comply. If in any doubt as to whether your alterations are affected by this document, the local building control department will be able to assist further. Later alterations of a building must not remove or reduce its accessibility features.

Part N. Glazing – safety in relation to impact, opening and cleaning

Part N was Repealed in 2013 and these measures were moved into a new consolidated Part K in 2013 (See above).

Part P. Electrical safety – dwellings

New rules for electrical safety in the home, the garden and its outbuildings. This part only applies to dwellings (in some cases, buildings that would be exempt but which take their electrical supply from a dwelling). Several government approved competent persons schemes support Part P.

Reasonable provision shall be made in the design, installation, inspection and testing of electrical installations in order to protect persons from fire or injury.

Sufficient information shall be provided so that persons wishing to operate, maintain or alter an electrical installation can do so with reasonable safety.

Certain types of work require notification to the local authority for building control. In England this is only work within 'Zone 1' of a bathroom, and new consumer units and complete new circuits. In Wales there are more 'notifiable works' including wiring in kitchens and gardens. Installers who are members of an approved "Competent Persons Scheme" may carry out such electrical work without the need to submit many such formal building regulations applications, instead notification is performed via their trade body.

Part Q. Security

In 2015 a new requirement, Part Q, came into force.

Part Q talks about security in a dwelling with reasonable provisions needing to have been made to resist unauthorised access to; any dwelling or any part of a building from which access can be gained to a flat within the building.

Exempt buildings

Exempt buildings include:

  • CLASS I Buildings controlled under other legislation e.g. Any building in which explosives are manufactured or stored under a licence granted under the manufacture and storage of explosives or nuclear-related buildings or an ancient monument.
  • CLASS II Buildings not frequented by people (unless close to an existing building).
  • CLASS III Greenhouses and agricultural buildings (not used for retail).
  • CLASS IV Temporary buildings (erected for less than 28 days).
  • CLASS V Ancillary buildings.
  • CLASS VI Small detached buildings (garages, garden storage sheds/huts) (less than 30 square metres floor area with no sleeping accommodation therein).
  • CLASS VII Extensions – porches, covered ways, conservatories, (less than 30 square metres floor area).

The Building Regulations 2000 have been amended five times since the original statutory instrument was published. A new consolidated edition was published in 2010 – the Building Regulations 2010. These have also now been amended five times since 2010. It is good practice to have exemption confirmed by the relevant local authority prior to starting construction works or alterations. The latest statutory instrument gives the full conditions of exemptions (and any newly controlled buildings).

Crown buildings (national government buildings) are no longer totally exempt the Building Regulations. All Crown buildings must comply with the energy efficiency measures set out in Part L. This is due to EU laws requiring higher energy efficiency in all buildings (new and existing) under European "climate change" measures such as the EU Energy Performance of Buildings Directive. EU law requires public buildings to be "good energy practice" examples.

New energy regulationshave been made to fully implement these EU laws, where they fall outside the scope of the building regulations.