The side return extension is one of the most common domestic building projects in the UK and in the Spring of 2015, we did just that to transform our 1899 Victorian Terrace in Surrey.

The millions of terraced and semi-detached houses that define so much of our urban landscape are ripe for this addition. But side return extensions need to be thought through properly. Get it wrong and this ‘improvement’ is not just disappointing, but can damage the light, flow and quality of your existing space rather than improve it.

These properties are good quality pieces of design that ooze potential but the dated layouts just simply do not work for us anymore as they reflect a bygone social structure with smaller separate rooms, separate kitchens and bathroom add on’s stuck out in the rear away from the main living space. So, how do we overcome this and make these properties work for 21st Century living? The answer is the side return extension!

The most important advice I can give, for a basic side return extension, is that you do not need to spend thousands on an architect, which, most people think is a must, and before you’ve even started, you are already a few thousand pounds in to your budget. People also assume you need an architect to produce the floor plans and elevations for your planning permission application. However, most of these extensions do not require planning permission and can be built under Permitted Development as the government have relaxed the rules on PD allowing you to build single storey extensions up to 6m (for terrace and semi-detached) from the original house under the ‘neighbour consultation scheme’. For a detached house it is up to 8m. This means you are not applying for planning permission which every Tom, Dick and Harry is able to have a say on. The neighbour consultation scheme just involves your immediate neighbours that share a boundary with you. For your floor plans and elevations, well, you can do these yourself or employ a CAD technician. All the council want to know is are you abiding by the Permitted Development rules i.e. staying within the 6m allowance. You can read the criteria in more depth on the online planning portal.

Of course if you are under taking a more complex side return extension then you may want to employ an architect. But for ours, a very simple design, there was no need.

There are so many ways this could be designed which all comes down to the space you have and most importantly, your budget. So I am going to talk about our side return extension, and the design and layout we went for.

Here are my drawings. Very basic, because this is all they need, and it saved me a fortune!



You will however need to employ a structural engineer to produce your structural drawings and load bearing calculations which you need for building regulations to apply for building notice. This is the next step after you have your permitted development approved. Building notice is a requirement for building regulations and this allows a building inspector to visit the build at each stage to sign it off. This is to ensure your builder is complying with current building regs. This then gives you final sign off at the end to prove you have complied with building regs. You will be issues a certificate which is a legal document that you will need when you come to sell the property.

Light is very important when planning your side return extension and the space is often long and thin which can create a tunnel feel if not designed properly. Make sure you include large Velux windows on pitched roofs and roof lanterns on flat roofs. The area also needs to be zoned in to different areas such as the kitchen, dining area and sitting area. Make sure you have plenty of space for these areas or it can feel very cramped.

I also strongly recommend spending the extra money on aluminium bi-folding doors over uPVC as they will last a lot longer due to the quality, they are also much more attractive. The runners on bi-folding doors are delicate and can often go wrong. The saying ‘you get what you pay for’ is very true. Our extension is 3.7m wide which is a common size for a terrace house, meaning our bi-folding doors are 2m wide by 2.1m in height. Sliding doors were not an option as the opening wasn’t wide enough. Bi-folding doors have a master door which opens independently which can be used as your everyday back door. As our garden is south-facing it is extremely sunny in the summer so the doors are open all the way a lot. Bringing the garden into the house and vice versa is fantastic. It makes the house feel even bigger as the side return extension has allowed the garden to become part of the house.

Here are some before shots of the house in the state we bought it in before works started.






Here are some during shots.


The soil stack that you can see in the photo below was re-routed through the new extension roof and down the new wall.


































And the finished result. We couldn’t have been more happy with the end result.

Ground Floor (10)

Ground Floor (12)

Ground Floor (9)

Ground Floor (6)

Ground Floor (3)


Ground Floor (1)

a (54)


1 (34)

1 (35)

Hook Rd (19)



  1. I love your design you’ve made adding an extention look straight forward, We’ve been considering a side return extension for several years but wanted to keep it simple and on a budget, yours is beautiful !
    I’ve looked at your deas and cannot work out where all your pipe work has gone and the boiler, this is one thing that I can’t work out where to put, cause they usually need to be on an outside wall. One of the reasons we still haven’t got an extension.


    1. Thank you. Yes, you must do the side return extension! The boiler is in the last cupboard closest to the bi-folds so it vents right out to the external wall. The cupboard is also used for the pull-out bin, broom and mop etc. Saying that, the whole of that wall is extenal. It’s the boundary wall.


      1. Hi Claire
        Can you adviae me what is aproxymatly budget that you spend on this L side extension,no furniture including,just structural works


      2. I wouldn’t like to say. Every side return extension is different depending on the area you live in (labour costs vary up and down the country), the level of specifiction you go to, whether there’s drains to be moved, access, size of steels, how many steels etc etc. So many factors. Could vary between 40-60k. You’d need to get a few quotes.


      3. HI claire, ive just heard back from the council ,they have said no to permitted development basically because of the implications a side return would have on my neighbour , and as shown in the planning portal the stepped nature of the original house , you can only build two 3m boxes one from the main wall, and one from the end of the kitchen wall, without joining them up. I see you already had a downstairs bathroom projecting out from the kitchen , so you only had to build out level with that. Wether your local council has a different planning portal to mine who knows , if you were living in sittingbourne where I am ,the council would make you submit a FULL PLANNING APPLICATION , so a word of caution to would be hopefull diyer’s .



      4. Hi David, no we went deeper than the old bathroom on the end, it was knocked down. If you comply with the rules of PD then you don’t need planning hence why we didn’t. We have built 3 more since this all under PD. If you want to build more than what they allow for this then yes you will need full planning. It is all very clear on the online portal. This blog post is about this build, not others 🙂


  2. I’ve been looking and researching for many ideas as to how to approach our sude return extension but this is the first time I see one as detailed and really beautiful as yours. Congratulations!!! I also was wondering where all the pipes went? I mean, I have the same situation as you had where my next door neighbour and me do not have a portion wall so we would have to create one as you did but am so petrified to even imagine how that conversation would go, any tips?


    1. Thank you Claudia. I am not sure what you mean by where do the pipes go, assuming you mean the soil stack and central heating pipes which are built in to the extension. I am also not sure what you mean about a portion wall. Do you mean a party or boundary wall? We built the new wall 1cm in from the boundary so legally it is not a party wall. You don’t have to worry about a conversation with your neighbour, you are well within your rights to build a side return extension. Permitted development still goes through the same 8 week process with the council as planning does, the only difference is only the neighbours that share a boundary with you have a say, where as planning, everyone seems to get involved! The neighbour on that boundary can only cause problems if the extension was so seriously cut their natural light for example, the council will only take into consideration legit reasons. After all it is permitted development and as long as you are building within the PD rules, then you will be given permission. Good luck.


  3. Hi Claire, fantastic work and a really useful post. We are considering a similar extension although potentially on a smaller scale.

    My only question relates to the other comments.

    How did you route the existing soil stack and drains?

    I can see them on the before picture in more or less exactly the same place as ours on the side and I presume main drains run up the side of existing alley area.

    Did you dig up existing drains outside or have you built over the top with hidden floor access somehow?

    Thanks in advance.


  4. Our kitchen is a mirror to the top picture of the kitchen before the work was done. Were looking to do this and would love to know the cost as we’re keen to do something exactly the same and have a budget or what we could borrow


  5. I was wondering if you might be able to advise.. we have purchased a semi detached house that has been granted permitted development to have a side return, but the previous owners also applied and had had accepted permitted development to just extend backwards from the existing structure.
    Do you know if we are able to essentially combine the x2 plans- but I know it would create an L shape, but I don’t know if that is allowed to combine x2 sets of permitted development? or if it would mean applying for planning permission?


    1. Hi Melissa, every council is different so you will need to take this up with them but from my understanding you will need to re-submit an application for the extension you plan to do. Your drawings would have to show the L-shape extension so the council is clear on your proposal. They may accept it as PD or they may say it has to be a full planning application. Give them a call and speak to the on-duty planning officer.


      1. Hi, looks great and thinking of doing something similar, one question if I may, how did you get around the issue of light for your next door neighbour? we are joined like you are and I have concerns in getting approval.

        Many thanks in advanced


      2. A ground floor side return extension on period semi’s and terraces are fine. They are the most common extension and can often be done under permitted development rather than full planning. Next door will also extend, or if they dont, the next owners will!


  6. Hi Claire,

    Love your work, have been following you on Instagram for some time!

    I am in the process of buying a semi detached Victorian house in Walton-on-Thames with the idea to do a similar extension to this (side return and maybe go further out the back too). Having looked at your drawings, the overall width of this room is very similar to what I want to create (It’ll be about 12′), so I was wondering if your kitchen space would have been big enough to have an island incorporated into it, similar to your Millwater kitchen?

    Thanks so much


  7. Hi claire

    I am about to undertake a very similar project to your 1899 victorian terrace ( no 223 ) , just out of interest what steel beam sizes did your structural engineer come up with ? as my kitchen floor steps down and there isn’t room to have the steels under the floor joists like yours or even keep them at the same level without compromising the head height from existing to extension .
    Any info would be much appreciated .
    Dave Busbridge


    1. Goodness , I’d have absolutely no idea without going back from old paperwork from a few years ago. Your structural engineer will calculate what size steels you need, they won’t be the same as here, every house is different.


  8. It is an amazing extension, I will be nicking some ideas! But what did you do with the soil pipe from the upstairs bathroom?


  9. Hi Claire

    This is a great piece for people considering a side return. I am looking to buy a terrace or semi in an area where houses do not typically have the benefit of side access and I note from your pictures that there doesn’t seem to be side access. Did this pose any challenges for the builders? For example did they need to dig out the footings by hand and crane in / out materials? I am concerned about the additional cost this might pose. Any thoughts / advice appreciated.



    1. Hello, the house has a coal mans passage which is rear access for the row of terraces. I should think every row has this as they’re historically written into the deeds so they have to be kept. So check if you have this on the new house, i’d be surprised if you didn’t.


  10. Finally a post I can relate to! We have looked into this & been told we can only go 3 metres from our original wall which essentially means we can only extend the ‘L’ Shape that we already have. Did you have any issues getting your drawings approved. Presumably the bit that runs down the side of the old kitchen the ‘side return’ is longer than 3 metres from your original wall? Thanks


    1. They have bought in a new law so you can build under permitted development rather than needing planning permission. For a detached house you can build up to 8m (used to be 4m) and a terrace or semi is 6m (used to be 3m). We built 5.7m so no problems at all, it was under PD. If you go onto the planning portal website it explains this. Here is the link –

      Click to access extensions.pdf


  11. Hello, many thanks for sharing in such detail. My house is very similar and I have been wondering how to extend it. Could you tell me how long it took you? and what the cost was? I see you had to give up the downstairs bathroom, how did you solve that? I would need to retain a downstairs bathroom for my elderly mother.
    Many thanks,


    1. Hi Sarah, the works took approx. 16 weeks with me project managing on site most days. There was already a bathroom upstairs so knocking down the moldy and damp shower room that was added in the 80’s wasn’t an issue. To keep a bathroom downstairs in houses of this style (long and thin) means you block the view to garden and unable to have large bi-folding doors onto the garden. If you need one for your mother I would suggest having it on the staircase wall so it’s much further back so it doesn’t ruin the open plan feeling with views onto the garden. This will also make the house more appealing for re-sale as the bathroom can be changed into a utility room but I would strongly recommend avoiding having a bathroom at the end for the above reasons.


  12. Hi Claire,

    I have exactly the same house and would like to do the exact same extension, would you be available for a call?

    Thanks Andy.


  13. Hi Claire,

    Lovely extension, great job.

    I have a question regarding “project management”. You said that you managed the project yourself and was on site each day. Please could you expand on what’s involved in managing the project? Did you have to get quotes from all the individual trades separately e.g. Building contractors, plumbers, electricians etc then call them in as needed or did you use one firm that did everything? If you don’t project manage yourself who does this for you?

    Also, did you consider hiding the steel beams in the ceiling or was this not an option?

    Many thanks,



  14. Hi Claire,

    I’ve wanted to proceed with the side return extension, obviously, every design is different but what did you use the front room of the house for after the renovation? As I have the staircase situated in the same position as you do above, I just don’t want to make this a redundant room and become more or less a large hallway to one large room?



    1. This is the problem when front doors are in the front room. They become redundant large hallways. We kept the door closed most of the time as it was a cold room facing north at the front of the house. If you go to portfolio on my website, you will see the house at the bottom which has some photos of the front room/hall. I should think the new owners also have it closed off as the big open south facing living space is at the rear with the garden.


  15. Hi Claire,
    This is absolutely beautiful. We have an exact mirror image of this property and are hoping to do something very similar in the new year. It’s very smart how you have approached this as it doesn’t appear that you’ve had to move much in the way of plumbing and such.
    Just a curious question, did you have your washer and dryer in the kitchen area?
    Thank you


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