Building Regulations and Conservatories

Recently the laws on building regulations were changed.  If you look at the guidance on the planning portal about whether a conservatory needs building regulations you might notice that the line that talks about the glazing being 75% or more of the total roof area and 50% or more of the wall area has gone.

What it des not say is what exactly constitutes a conservatory and that leaves the definition down to individual planning authorities.  On my recent post about this I checked in with one authority and the clear answer was they are using the old percentages from the previous rules as part of the definition of a conservatory.  However, I also have news from some installers that other authorities are now not requiring these glazing percentages at all and are happy with orangeries and in some cases even completely solid roofs.

In the hope that it may help to clarify the rules or perhaps help some installers I have created this page as a place where people can drop comments in regarding the views of their own local authorites.  If you have asked the question and have received a resonse please copy it in here for others to see.  We need to see which authority it is, the person that responded as well as a clear response.  If you are copying in an email please keep in the date and time that their response was sent.

We do however suspect that in some cases, different officers in the same authority may have different views so please don’t use comments here as definitive but use them for guidance only.



  1. These are the comments emailed to me from a colleague whose area is covered by the Dorset building control

    I have spoken to EDDC and they are of the opinion that there is no change whatsoever! has info all building control issues within the majority or Dorset with particular attention to
    I must point out that the portal is more or less an independent government website and is aimed at giving general information to the public. It puts its own disclaimers all over it saying that all information must be checked with the relevant local authority!
    It is worth remembering that ‘conservatories’ are exempt from building regulations for a reason i.e. they are not of structural significance, if building control departments were to relax laws on what they class as a conservatory they will then be opening themselves up to a whole world of trouble with people trying to claim their brick built flat/solid/non translucent roofed extension is exempt!!
    For this reason I think it’s unlikely that the majority of the LA’s will change the rulings and my advice would be to continue to use the rulings we all know and love (75% glazed/translucent roof 50% glazed walls)!!

  2. jtwigge says:

    Well, thanks to Phil Coppell –, here is a document from the government communities web site that categorically states that the rule about the percentage of translucent material no longer applies in the definition of a conservatory:

    Search for “no longer applies” in the document to find the relevant bit.

    Quite how we are supposed to define a conservatory after that I don’t know. But, it might be worth pointing your local building office at this document for comment.

  3. Ray Bursey says:

    Having recently constructed a conservatory in the EDDC area you may be interested in our experience.
    We were fitting windows on a job for a trade customer when the client asked if we could build a conservatory on his raised patio with a tiled roof to complement the house roof, we checked with building control who confirmed they needed structural calculations, and thermal calculations which we duly provided, after the roof was installed we called out the LA inspector who was suprised at the size of the roof (45 degree pitch vaulted, straight gable exposed rafters). and asked if his structural engineer could check our design although our previous calculations had been accepted. We agreed to carry out minor modifications to satisfy the engineer and it was signed off. Following complaint from a neighbour the client had to submit an amendment to regularise the change from a 5 sided bellend victorian with a polycarbonate roof to a fully functioning sun lounge wth a solid tiled vaulted roof with glazed straight gable end which has added value to his home.
    The moral of the story is to work with the planners and building control to achieve the clients aims, and everyone wins.

    • Steve Williams says:

      Hi Ray,
      Thanks for your comments,

      Unfortunately you may have learned the hard way so to speak. In my January 2011 archived post titled

      “What consents do you need to add a conservatory to a property? Do you know what consents you require?”

      The last line on the post agrees entirely with your moral of the story

      “For the avoidance of doubt please contact your local planning and building regulations authority before undertaking any work”

      Don’t forget to sign up for my free email subscription so you recieve an email alert for my future posts

  4. Ian Leary says:

    Interesting site.

  5. John Bell says:

    There does appear to be a lot of local interpretation as to what is a conservatory. e.g. Charnwood district council “We considered in order to be considered a conservatory; at least ¾ of its roof and ½ of its walls must be constructed of a translucent material. If not, then this is an extension and a Building regulation application is required. (This is in line with LABC national guidance issued November 2010) ”

    Note the “We considered” but when you look at the differences between a porch and a conservatory, then the amount of glazing is immaterial.

    • Hi Jon,
      Thanks for your comments.
      It is confusing and I think different councils, view it in different ways.I have copied an exert sent to all authorities in March 2010

      C24 Building control bodies will wish to note that the exemption from the energy efficiency requirements for conservatories and porches has been clarified. This means that a conservatory will be exempt from the energy efficiency requirements only where: `
      • it is at ground level;
      • it does not exceed 30 m2 in floor area;
      • the walls, windows and doors separating the conservatory or porch 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; and
      • the fixed heating system of the building to which the conservatory

      Below is a link to document from the government communities web site that categorically states that the rule about the percentage of translucent material no longer applies in the definition of a conservatory sent to all authorities in March 2010. Pay particular attention to paragraph C24


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