Building regulations

Explains what building regulations are and do they apply to conservatories or porches. Also provides information on building regulations for extensions, garage extensions, detached garages, loft conversions, internal alterations, replacement windows and doors, converting your house to an office or shop, installing fittings and appliances and the types of work that are exempt from building regulations.

What are the Building Regulations?

The Building Act 1984 allows for the creation by the secretary of state of regulations to control the minimum standard of building work.
The standards exist to protect the health and safety of people in and around buildings, to provide for energy conservation and to provide access and facilities for disabled people.
The regulations are referred to as the Building Regulations and take the form of simple functional requirements that must be met.

They cover subjects such as structure, fire safety, ventilation, drainage and glazing (a full list is given below).

  • Part A (Structural Safety)
  • Part B (Fire Safety)
  • Part C (Resistance to Contaminants and Moisture)
  • Part D (Toxic Substances)
  • Part E (Resistance to Sound)
  • Part F (Ventilation)
  • Part G (Sanitation, Hot Water Safety and Water Efficiency)
  • Part H (Drainage and Waster Disposal)
  • Part J (Heat Producing Appliances)
  • Part K (Protection from Falling)
  • Part L (Conservation of Fuel and Power)
  • Part M (Access to and Use of Buildings)
  • Part N (Glazing Safety) (Withdrawn)
  • Part P (Electrical Safety)
  • Part Q (Security)
  • Part R (Physical infrastructure for high speed electronic communications networks
  • Regulation 7 (Materials and workmanship)

Each of the parts is supported by a separate document called an approved document, which contains practical and technical guidance on ways in which the requirements can be met. You can view the documents on the planning portal website.  Planning portal (external website)

The approved documentsare only one method of complying with the requirements but have become almost the standards to be adhered to. Other guidance does exist on good building practice with British Standards and Codes of Practice being examples.  Relevant British Standards can be found within the approved documents.

Do the Building Regulations apply to conservatories and porches? 

Conservatories or porches, meeting the following listed conditions will not require the submission of a building regulation application, however these rules do not apply to planning permissionand you are advised to read the guidance.

The conditions are:

1. The internal floor area of the conservatory or porch must not be more than 30m2.
2. The walls and roof of the conservatory must be substantially glazed with transparent or translucent material - i.e. glass / plastic sheeting or equivalent.
3. The glazing of the conservatory must meet the requirements for critical location
safety glazing (see below).
4. The door between the dwelling and conservatory/porch must remain in-situ.

Should you have to widen an existing opening to form a door opening, which will require the provision of new structural lintels - this alone will require a building regulation application.

It is advisable that the porch or conservatory is constructed so as not to restrict access to any habitable room escape window, including loft escape windows.

You are also advised to check your deeds for any restrictions that apply to extending your property.

It is a ‘Material Alteration’ which would require the submission of a building regulation application, if the works you are undertaking make access to or access into the dwelling, any worse than it is now. Be careful that the new doors do not have clear opening widths less than the existing doors, that thresholds are provided where none existed previously, (particularly with upvc doors) and that the manoeuvring room into the dwelling is sufficient to allow wheel chair access.

Also the construction / extensions must not obstruct access pathways up to the main dwelling entrance doors.


If the conservatory is to have electricity supplied from a source shared with or located within the dwelling, then the building regulations apply to the electrical works. You will be required to submit a building regulation application.

Critical Locations and Safety Glass Requirements

To comply with the building regulations glazing requirements to ‘Critical Locations’ (as indicated below) there should be safety glass or guards to protect people from injury. The most likely locations for accidental impacts, which could lead to cutting and piercing injuries are in doors, door side panels and low level glass in walls and partitions.

Critical locations are considered to be:

  • glazing in doors - wholly or partially within 1500mm from floor level
  • glazing adjacent to doors - wholly or partially within 300mm of the edge of a door and which is also wholly or partially within 1500mm from floor level
  • low Level glazing - not covered in the above - glazing that is wholly or partially within 800mm from floor level.

Conservatories and porches (pdf 45kb opens in new window)

Glazing in ‘Critical Locations’ should break safely, i.e. laminated or toughened class C safety glass complying with BS6206. Or if it is installed in a door side panel and has a pane exceeding 900mm it should be class B of BS 6206.

Please note:

  • Ordinary wired glass is not safety glass
  • For double-glazing the rules apply to both panes
  • All safety glazing should be permanently marked in accordance with BS6206 The markings should be still visible after the glass has been fitted and the beading and pointing has been completed.

Will I need Building Regulations for my conservatory?

Building regulations approval will not be required providing the following criteria is met:

  • The conservatory is at ground level
  • It does not exceed 30m² in floor area
  • The walls, windows and doors separating the conservatory from the building to which it is attached have not been removed, or, if removed, have been replaced by a wall, window or door which meets the current requirements for energy efficiency for walls, windows and doors
  • The fixed heating system of the building to which the conservatory is attached has not been extended into the conservatory
  • It has a clear translucent roof and substantially glazed walls
  • It is used as a conservatory
  • The glazing satisfies the requirements of Approved Document N of Schedule 1
  • In all cases any fixed electrical installation must meet the requirements of approved document P - Electrical Safety

  Application Forms and Fee Sheet page.

Do I need Building Regulations to build an extension to my house?

Yes, however, a porch or conservatory built at ground floor level and under 30m2 in floor area is exempt provided that the glazing complies with the safety glazing requirements of the building regulations part N.

 Application Forms and Fee Sheet page.

Do I need Building Regulations to build a garage extension to my house, shop or office?

Yes, but a car port extension built at ground level, open on at least two sides and under 30m2 in floor area, is exempt.

 Application Forms and Fee Sheet page.

Charges can be found on our charges page.

Do I need Building Regulations to build a detached garage?

Yes, but a single storey garage at ground level, under 30m2 in floor area and with no sleeping accommodation, is exempt provided either:

  • It is built substantially of non-combustible materials
  • When built it has a clear space of 1 metre from the boundary of the property

  Application Forms and Fee Sheet page.

Charges can be found on our charges page.

Do I need Building Regulations to make internal alterations within my house, shop or office?

Yes. If the alterations are to the structure, such as the removal or part removal of a load bearing wall, joist, beam or chimney breast.
You may also need approval if in altering a house, work involves altering the drainage system, heating appliance or fire precaution measures.

  Application Forms and Fee Sheet page.

Do I need Building Regulations approval to install replacement windows and doors in my house, shop or office?

Yes. Legislation now requires most replacement windows and doors to comply with certain minimum standards.
To enable work to be monitored it is also a requirement to apply for permissionfrom the council before carrying out any work. For domestic premises however, instead of using the council to approve and inspect your proposals, you can employ the services of an appropriate competent persons scheme registered installer.

Competent persons scheme members do not have to apply to the council for permission as the standard of their work is monitored by an independent body but they do still need to notify building control of the works through the competent persons scheme.

Replacement doors only require consent if they contain over 50% glazing.

For many years, it has not been necessary to apply for building regulation consent when replacing windows in existing dwellings unless a structural alteration was involved. This usually only occurred when the existing opening was being made wider (which made the installation of a new support lintel necessary), or where the windows were part of a structural bay. All owners replacing windows need to obtain consent, and the new windows themselves will have to fully meet the requirements of the building regulations. Even if you are replacing only one window with one brought from a local DIY centre you still need to follow the guidance below.

It is important that householders obtain the necessary consent as solicitors will make a specific check for this when the property is sold.

You can either:

  • use an installer registered under a competent person scheme, in which case you do not need to make a building regulations application to the council. Your installer should then ensure your windows comply fully with the regulations and will supply you with a certificate confirming this when the installation is complete. You will also be offered the option of taking an insurance-backed guarantee. Please ensure that your installer is properly registered under the scheme before placing an order; or
  • make a building regulations applicationto your local authority, and in most cases the simplest way of doing this will be to submit a building notice. You should complete a replacement windows building notice form and return it to your local authority together with the appropriate charge at least two working days before removing the old window(s). If all is found to be satisfactory your local authority will approve the work. This may involve an officer calling at your property to check the installation of the new windows. You are likely to be asked by your solicitor to produce evidence of this approval if you sell your property, so please follow carefully the guidance given by your local authority to ensure a completion certificate can be issued for your work

If you use a contractor registered under a competent person scheme the cost should be built into the quotation for the works you are given. In all other cases the council will make a set charge for dealing with your building notice application.

There are certain regulations that the replacement windows and doors must comply with. Owners of listed buildings and buildings in conservation areas may not need to satisfy these requirements in all cases. However, it is still necessary to apply for consent through the local authority or a competent person scheme.

Please remember that separate planning permission may be required from the local authority for these works.

Thermal insulation

The replacement windows will need to meet the new thermal insulation requirements of the regulations. Please refer to Part L1B.

Please note: these values are very difficult to achieve and many double glazing units currently on sale will not meet these new standards.

Take great care when ordering new windows that your supplier can prove the glazing units used will satisfy the requirements, as the building control officer will need to see this proof before issuing a completion certificate. We would particularly recommend that you leave any labels on the glazing in place until after a satisfactory inspection has been carried out by the building control officer.

In some cases it may be permissible to use glazing units which do not meet the above specifications, but to do so you (or your supplier) would have to submit calculations to prove that the overall insulation requirements of the regulations would still be met. This may be possible if other insulation measures are undertaken at the same time as the window replacement - for example; installing cavity wall insulation or "topping up" loft insulation. The benefits gained by installing this extra insulation can be used to offset the higher losses through the glazing, but this should not be undertaken lightly. We would strongly advise you get any such calculations checked by the building control officer well before the replacement windows are installed, so that expensive mistakes can be avoided. 

Means of escape

All first floor windows in dwellings should ideally have opening lights large enough to allow you to escape through them if you were trapped in the room by a fire. This also applies to rooms in bungalows, which open into a hall (unless the hall itself has an external door through which you could escape).

To meet this requirement all such windows should have an unobstructed openable area of at least 0.33m2 and be not less than 450mm high and 450mm wide (the route through the window may be at an angle rather than straight through). The bottom of the openable area should be less than 1100mm above the floor.

If your existing windows do not have opening lights which meet the above requirements, we would strongly recommend for your own safety, that you take the opportunity to provide them in the replacement windows. This is not, however, a requirement of the regulations, which simply state that the replacement windows must be no worse than those they replace in this respect. Where the existing windows already have opening lights which are larger than the above requirements, those in the new windows can be reduced in size provided they are not reduced to less than that shown in the attached diagram below.

Means of escape (pdf 24kb opens in new window)

Safety Glazing

Low level glazing (glazed areas within 800mm of floor level) and glazing in doors within 1500mm of floor level should generally be of a type so that if broken, it will break safely. In practice this means such glazing should be either laminated or toughened. Ordinary glazing can still be used in small pane sizes, however, provided the glass is sufficiently strong to resist breakage. The approved document to part N of the building regulations gives maximum sizes according to the thickness of glass - for example, in a single pane less than 1.1m square - 8mm glass would be satisfactory. 

Structural safety

If the replacement windows are wider than those they replace, or involve the replacement of bay windows, then proper structural support is required above the window. In older buildings, the timber frame of the window was often sufficiently strong to carry the load of a wall or roof above it without a lintel. Obviously in these cases either a lintel needs to be installed when the window is replaced, or the new frame carefully reinforced to carry the load. Further advice on structural stability can be obtained from your local authority or from any member of a competent person scheme.


The building regulations require that adequate ventilation is provided for people in the building and this should be considered when deciding on the size of opening lights in the replacement windows. For most rooms, one or more opening windows totaling 5% of the floor area, with background "trickle" vents totaling 8000mm2 will be adequate. For kitchens, utility rooms and bathrooms an extract fan is also normally required. In some cases the existing windows may contain a permanent vent to supply combustion air to a heating appliance, although this is now rare. If this is the case, however, you should ensure that either the replacement window contains a similar permanent vent or that some other means of providing the required ventilation is installed at the same time.

  Application Forms and Fee Sheet page.

Do I need Building Regulations approval to convert my house to an office or shop?

No, if you are not proposing any building work to make the change. Where building work is proposed you probably will need approval if it affects the structure or fire precautions.

  Application Forms and Fee Sheet page.

Do I need Building Regulations approval to install fittings and appliances within my house, shop or office?

  • To install or alter the position of a WC, bath etc. – no, unless the work involves new, or an extension of, drainage or plumbing
  • To install, replace or alter the position of a heating appliance –
    • Gas - yes, unless the work is supervised by an approved installer under the Gas safety (Installation and Use) Regulations 1984
    • Solid fuel - yes, however certain works can be self-certified by companies registered under the Competent Person Scheme
    • Oil - yes, however certain works can be self-certified by companies registered under the Competent Person Scheme
    • Electric - no
  • To alter in any way the construction of fireplaces hearths or flues – yes
  • To install hot water storage - yes, if the water heater is unvented (i.e. supplied directly from the mains without an open expansion tank and no vent pipe to atmosphere) and has storage capacity greater than 15 litres. Such systems must be installed by persons competent to do so.

 Application Forms and Fee Sheet page.

What types of work are exempt from the Building Regulations?

The following buildings and extensions may be erected without submitting a building regulation application although you may still require planning permission.

A detached single storey building, i.e. garage or shed, that:

  • contains no sleeping accommodation
  • is no larger than 30m2 in floor area
  • is at least 1m from the boundary of the site if it is built from combustible materials i.e. timber
  • if it is less than 1m from the boundary it is built of substantially non-combustible material i.e. bricks, blocks and a tiled roof
  • complies with Part P of the Building Regulations Electrical Safety
  • Please note:  if the floor area is less than 15m2 it can be built of timber and sited within 1m of the boundary.

The extension of a building by adding at ground level a conservatory, porch or carport which is:

  • no larger than 30m2 in floor area
  • separated from the existing dwelling by external quality draught-stripped doors or windows
  • and in the case of a carport is open on at least two sides.

What is a conservatory?

To be classed as a conservatory the extension must have:

  • at least 75% of its roof made of translucent material i.e. glass or polycarbonate sheeting
  • at least 50% of its walls made of translucent material
  • Further information on conservatories can be found on this page.

Even if you don't need to submit a building regulations application you should still think about:

  • glazing - all glazing must satisfy the requirements of Part N of the Building Regulations and safety glass must be installed when:
    • glass in doors and sidelights either side of a door is less than 1500mm above floor level
    • windows have a sill height of less than 800mm from the floor
  • ventilation - boiler flues and ventilation inlets for boilers and fireplaces should not be covered by the conservatory
  • electrical work - electrical work needs to comply with Part P of the building regulations. Where electric sockets and lighting are installed in the building, the best option is to employ an electrician who is a member of a competent persons scheme and can self-certify their work. Alternatively, you may need to make a building regulations application
  • plumbing - If the new area is to include waste plumbing i.e. for a new w.c., shower or bath, foul water drainage etc then a building regulations application will need to be made for those works only
  • heating - If a fixed heating installation is proposed it should have its own separate on/off temperature controls. The installer should be competent person scheme registered or a building regulation application will be needed. Please contact us for further advice
  • drains - Foul and surface water drains can be built over as long as they are properly protected, to prevent them breaking, with no additional weight being placed on them as a result of the works. The new foundations should be taken below the level of the drain and suitable lintels should be provided where they cross the foundations.

More comprehensive guidance on common building projects and via the 'Interactive House' can be found at the Planning Portal.

Planning Portal (external website)

If you are having construction or refurbishment work done, you may need to notify the Health and Safety Executive (HSE) and you may have other duties as well.

Health and Safety Executive (external website)

 Application Forms and Fee Sheet page.