Building Control (Building Regulations)

Building Control or Building Regulations relate to the technical aspects of the build, they aim to ensure buildings are constructed to good standards.  The majority of projects we undertake require Building Control Approval, however some conservatories can be exempt.

Approval is typically sought from the local authority, however it is an option to use a private approved inspector. An application will require submission of technical details to the inspector then a series of site visits throughout the course of the build. At the end a Completion Certificate will be issued which can be helpful if the property is sold in the future.

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Building Control FAQs

Are conservatories exempt from Building Control?

For a conservatory/orangery to be exempt from building control, the internal floor area of the conservatory must be less than 30m², the conservatory must be built at ground level and the conservatory should be separated from the house by doors of external quality.

Additional information can be found further down the page.


What is a Building Notice?

There are two ways to apply for Building Control approval, a Building Notice and a Full Plans Submission.

With the Full Plans Submission, technical drawings are sent to Building Control a few months before the build commences and the plans are checked and approved in principle. There are then a series of site inspections throughout the build.

For single storey extensions such as orangeries, the plan-checking stage can be skipped and we can go straight to the site inspections. This is known as a Building Notice.


What if I don't get Building Control approval when I need it?

If the structure is dangerous the local authority could, and indeed should, take enforcement action to rectify or even demolish it. Otherwise it is almost unheard of for them to be concerned.

The lack of Building Control approval may become an issue during the conveyancing process if the property is sold at a future date. However this is easily overcome by purchasing an indemnity insurance (approx £150) which protects the new buyer against any action the local authority may take.

We don’t recommend this course of action, but we see this quite a lot from clients who have bought a property with conservatory built by the previous owners. The new occupants contact us to needing to update or replace the old conservatory. Often the conservatory is open to the house, building control approval was never given yet the sale has still gone through, facilitated by the indemnity insurance or the keenness of the buyers.


How do you overcome the 25% of floor area glazing rule?

We use better components that are required by Building Control which allows us to use more glass.

Often we will also produce quite in-depth energy calculations (SAP calcs) taking into account many other factors.

What is the difference between Planning Permission and Building Control?

Planning permission relates to the size and design of the extension, building regulations or building control cover the technical aspects.

More information on this article: Differences between planning permission and building regs

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Building Control Requirements

The Merged Approved Documents issued in March 2023 covering the Building Regulations 2010 and subsequent amendments is available for download below. It is 1504 pages long.

Building Regulations Documents


Within those 1504 pages, there are numerous regulations that may be relevant to an orangery build, but we find there are three main areas that need to be considered on every project:

Thermal Efficiency for the Conservation of Fuel and Power

The main hurdle to overcome in getting building control approval is meeting the insulation standards which are constantly being ratcheted up in the drive towards Net Zero.  The starting point for a domestic extension is that it should have an area of glazing equivalent to no more than 25% of the floor area. This would mean for a 20 square metre extension the total permitted area of glazing would be 5 square metres, which isn’t much more than a large set of doors.

We can justify an increased area of glazing by using products with a better insulation value than the accepted standard and also taking into account any exiting windows and doors which will be covered up by the new extension.

Depending on the orangery design (more walls make life easier!) and type of house, the above measures may still not be enough. The next step is to undertake SAP (Standard Assessment Procedure) calculations, a method of determining energy use of the building overall. This may involve additional work such as increased loft insulation in the main building to offset any extra heat losses from the conservatory.



The other issue that arises is foundation depth. On all our conservatories or orangeries, regardless of whether building control approval is required or not, we dig to a minimum of 1000mm (one metre) for footings.

Normally, one metre footings are fine, but it does depend on the site conditions. The main problems we encounter in the local area are the combination of high-shrinkage clay, large trees that consume a lot of water and “brownfield” sites that have all manner of things below the ground. However, if your ground is stone or chalk, or there are no large trees in the vicinity, it is unlikely to be an issue.

When building control become involved, they tend to err hugely on the side of caution. As there is no separate category for conservatories, the foundations have to be suitable for a two-story building. In the past we have had to dig 2.5 metre (over eight feet) foundations for a 600mm (two feet) wall!

The other method is to use mini-piles, steel columns that are driven into the ground about eight metres deep. This method is quicker, cleaner and easier when access is difficult than digging a deep trench for footings, and tends to become more economical when a trench depth of more than 2000mm is required.


Structural Integrity

Engineer’s Structural Calculations will be required for most of our projects. Whilst a lot of the structural designs are repeatable, site-specific calculations are required due to profession indemnity insurance.  These calculations will specify the sizes of the beams supporting the roof lantern, the specifications of any columns or frames proving lateral stability to the orangery, and the design of any new openings to the house.

In most cases we use glulam (glued-laminated) timber beams to support the roof lantern rather than steel. Whilst the steel price does fluctuate, it is generally cheaper than glulams, however glulams are lighter and easier to work with, more stable and better insulated.

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When Are Conservatories Exempt From Building Control?

If the conservatory or orangery is going to be open to the house then it does require Building Control approval. There are some other requirements listed below, but the opening the house is the main criteria.

There used to be a requirement stating that 75% of the roof needed to be glazed, but this was counter-productive in terms of ensuring the conservatory was energy efficient, so has been dropped in recent years.

Building Control Exemptions

For a conservatory/orangery to be exempt from building regulations, the most important factors are:

  • The internal floor area of the conservatory must be less than 30m²

  • The conservatory must be built at ground level

  • The conservatory should be separated from the house by doors of external quality

  • Glazing and electrical installations should conform to current safety regulations

Find out more


The UK government’s official page on building regulations approval. This page offers comprehensive information on the process of obtaining building regulations approval for construction projects in England

The UK’s Planning Portal provides guidance on building regulations, how to get approval, and the processes involved in building control applications. It includes links to approved documents and resources for both local authorities and private sector professionals.  Planning Portal

The Local Authority Building Control (LABC) website offers comprehensive resources for homeowners and professionals involved in building projects in England and Wales. It provides guidance on building regulations, the approval process, and maintaining compliance. The site features sections on training, qualifications, news, and awards. It also offers tools for finding local building control teams and approved inspectors, and provides practical advice for various construction and renovation projects. LABC


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