Glass extensions for listed buildings – how do I get approved?

For many home or property owners, making any changes to a listed building can be a daunting task. The maze of regulations and restrictions in place would make the final scene of The Shining look like a game of Mousetrap, and the words ‘your application has been denied’ are infinitely more terrifying than ‘Here’s Johnny’.


01 Feb 2022


Simon McAuliffe

We’ve worked with all kinds of historical properties over the years, and we’re familiar with the gauntlet of designing and crafting glass extensions for listed buildings. We’ve put together this article to clear some of the fog around the planning and application process, and highlight the types of extensions that will likely ‘make the grade’.

Why are buildings listed?


The term ‘listed building’ is a fairly common one in the British property lexicon. If you’re going to get your extension approved it’s really important to understand not only what this means, but also the reasons why certain buildings are listed.


This might not seem immediately relevant, but if you understand the factors that are likely to lead to your designs getting approved or not, you stand a much better chance of receiving that green tick.


Listed buildings are recognised for their historical or architectural significance, and are broken down into a few different categories. These include Grade I, Grade II*, and Grade II.


Grade I

Grade I buildings are the cream of the crop. The holy grail when it comes to listings. Only 2.5% of all listed properties fall into this category, and they’re identified for their ‘exceptional’ historical significance and interest. Think churches, cathedrals, and castles.


Grade II*

It might sound a bit like an old O-level score, but Grade II* listed buildings are one tier down from Grade I. They’re recognised for their significant place in history and their ‘more than special’ interest. Around 5.8% of listed buildings are Grade II*.


Grade II

Chances are, if you own or are working on a listed building, it falls into the category known as Grade II. The vast majority (91.7%, in fact) of listed buildings in the UK are Grade II, which indicates they are of special interest.


What does this mean for a homeowner?


So if a building is of special interest, what implication does this have on the kind of renovation work the owner can undertake?


Firstly, a building being listed doesn’t mean it can’t be changed. It doesn’t even necessarily mean it’s going to be hard to change. All this signifies is that the character of the building is important, and that any alterations that you plan to make will need to take your home’s unique aesthetic qualities and history into account.


For example, if your property is adorned with centuries-old windows with charming wooden frames, you probably won’t be allowed to replace these with low-budget UPVC double glazing. In fact you almost definitely won’t be allowed.


If, however, you apply to add a visually unobtrusive glass extension at the rear of the home – one that won’t have any negative impact on the character of the property itself – then you’re far more likely to get your application approved.


What permissions do I need?


While improvements and renovations to all buildings in the UK are subject to Planning Permission, listed buildings require specific ‘Listed Building Consent’ from the local planning authority.


If you’re planning to make any changes to your property that will potentially impact upon its character, this is the consent you’ll need. Importantly, you will have to obtain Planning Permission, Building Regulations approval and Listed Building Consent in order to extend your home. Making any changes without this consent is a criminal offence.


How do I get Listed Building Consent?


Before you hire any professionals, or start waking up in a cold sweat about your own skills as a draftsman, there’s an important (and easy) step you should take: talk to your local authority Conservation Officer.


Every building is unique, and the factors that will influence whether your planned extension gets approval or not will differ greatly. Your local Conservation Officer can advise you as to the things that will influence the approval (or not) of your application.


With this in mind, when it comes to actually putting together your proposal, it’s important to do your homework. Research the history of your building thoroughly, understand the things that contribute to its specific character, and take steps to show how you’ve factored this into your proposed changes.


It’s also a very good idea to hire an architect. They will be able to help you to design and draw up a proposal that not only serves the practical purpose you need, but conforms to the advice you’ve been given by your Conservation Officer.


The listed building consent application process


Once you have received the proper advice, and put together an appropriate proposal, the application process itself is fairly straightforward. If you’ve already made some pre-application enquiries (to avoid a swift rejection), you simply submit your proposal to your local authority.


They will then review your plans, and provided your project isn’t of enormous scale, will aim to grant a decision within eight weeks, though major proposals can take up to 13 weeks. This will include a statutory 21 day consultation period for neighbours, local amenities providers, and any other relevant parties.


Provided you’ve followed the advice of your Conservation Officer, architect and glazing specialist, your application should be approved. If you’re unsuccessful, however, you’ll be given some written information as to why this is the case (although this is usually in government legalese, and you may need an expert to decipher it). With a bit of luck, you can then use this to make some alterations to your plans before re-applying successfully.


If you believe the decision is unreasonable, you can also appeal to the Secretary of State for Communities and Local Government (DCLG) within six months of being turned down.


Glass Extensions for Listed Buildings


Why are glass extensions a good choice?


Glass extensions have become one of the most popular ways to extend a listed home, for several reasons (and not least because they look rather lovely).


Innox Lodge, Hinton Charter House, Bath, Rural Somerset, listed Georgian detached, summer

One of the most important factors in getting approval for your proposed extension is the preservation of the original character of the building, which is one area in which glass extensions excel. The translucent property of glass means that a structural glazed extension doesn’t obscure the original building, and instead maintains the architectural quality of the original construction.


Another thing that often crops up with applications (particularly for much older buildings) is the need for a clear distinction between the old and new. While changes to the building itself often require the same materials and designs as the original, an extension to a listed home is an entirely new structure. Local authorities usually insist that rather than try to make your extension ‘blend in’ like a chameleon, you take steps to make it stand out from the rest of your home.


The goal isn’t for the extension to detract from the aesthetic qualities of the building – quite the opposite – but instead to be subtly but clearly identifiable from the original structure. Essentially, the Conservation Officer will want you to make it as obvious as possible which parts of the building are old, and which parts are new.


Glass extensions, particularly the frameless structural designs we build, serve this purpose to great effect. Their sleek modern design creates a strong visual contrast between the original building and the extension, but in way that’s wholly unobtrusive, and doesn’t end up negatively impacting the original qualities of the home.


What kind of glass extension should I choose?


Where possible, you should consult your architect and glazing specialist of choice, as the type of glass extension you opt for will depend both on the building and the purpose it will serve. Through advances in modern structural glazing, glass extensions can be used for kitchen spaces, glass offices, or to create the perfect environment for general living and relaxing.


Take a look at some of the historical projects we’ve worked on in the past if you’re struggling for a bit of inspiration!


Types of glass


Orangery Enclosure

When it comes to listed buildings, it’s nearly always best to go for glazing that’s as visually unobtrusive as possible. For this purpose, low iron glass is often the best option. This type of glazing contains less iron oxide, which is the thing that gives glass that ‘greeny’ tint.


It’s also a good idea to opt for frameless glazing solutions – the more glass (and less frame) on display, the more of the original building will be visible.


Consider the fact that even though your home is listed, the extension you’re planning is very much a new build – and as such needs to comply to the Building Regulations. These are strict, but very clear, and one of the things they insist upon (and rightly so) is energy efficiency.


As such, you’ll almost certainly need to opt for double (or triple) glazing, which offer the lowest ‘u-value’ (the measurement of how insulative glazing is). The glass we design at Cantifix uses the latest nanotechnology to reduce U-value to the smallest rate possible.


The design of the extension


While this will naturally be subjective, and different for every home, you’ll need to have a think about how your extension will be constructed. You’ll have to consider ventilation as well as energy efficiency, and you’ll have to work out whether you need to include an access point or door leading outside.


If this is the case, then it’s a good idea to opt for a door that’s as slim and minimal as possible. Sliding solutions are almost always the best choice, and if it’s possible then a frameless option – such as the Sky-Frame sliding glass doors we offer – is always the way to go.


Structurally speaking, your architect and specialist will be able to determine what will work best. It’s even possible to install glass beams, meaning that not only will your extension be frameless, it’ll be almost entirely crystal clear. That will likely go down well with the Conservation Officer!




While there’s an awful lot to think about when it comes to extending a listed building, there are a few particularly pivotal takeaways. First and foremost, get as clued up as you can – get in touch with your local authority as early as possible to speak to them about your plans, find out what they would recommend, and do as much research as you can into the history of your building.


When it comes to putting together your proposal and drafting the designs for your glass extension, get in touch with the right professionals. Consulting an architect is nearly always the best choice — and when it comes to actually designing the glazing, we heartily recommend that you get in touch with a specialist such as Cantifix. (Feel free to contact us if you have any questions about glass extensions or other glass installations, too!)