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Where do i start with planning a single storey extension? how much should i be paying for architects plans?

I live in an average sized semi detatched house. I am planning a small single storey extension at the side of my house (approx 10m square) to extend my kitchen. I have done some research on the internet and looked at previous questions on here, but it's actually thrown up as many questions as it has answered!!
I'm not sure where to start as I don't know exactly what I want (just a kitchen extension or a smaller kitchen extention and separate utility room?) I don't know whether to get some building quotes first for a rough estimate or get plans drawn up first (will architects actually give me advice on what to have done or do I need to tell them exactly what I require?)
Also, I'm unsure if I need planning permission because although the extension is only small it will be going right up to my garden boundary. Do architects advise on this? (I don't want to pay for plans only to find I can't build what I want to).
On that subject, roughly how much would plans cost from an architect? (also, I've read on other websites that you can use a technician instead of an architect to produce plans. What is the difference?)
I understand the concept of planning permission, but I also keep reading about planning notices, certificate of lawfulness and building regulation fees. What are these and do I need them, or are they covered by planning permission if I get that?
Roughly how long will all this take, and how long to build the extension itself? (I am looking ahead to how much time I will need to take off work to be at home whilst the building work is carried out)
Sorry there are so many questions, but any advice on any of my questions would be appreciated. I will be looking for quotes from tradespeople on this website once I am ready to go ahead with this work (hopefully this April/May/June time)
Thanks very much, Janice

8 Answers from MyBuilder Extension Builders

Best Answer


It can be a little daunting but selecting and using the right team of people will make sure everything runs as smoothly as possible.
Firstly I would advise that from your first initial meeting with your architect to getting started on site should take no more than 8 weeks providing there are no unforeseen issues, party wall agreements etc. The build time, again, providing there are no unforeseen problems such as drain runs in your footings etc should be approximately 12 weeks.
A simple rule of thumb to work out a very rough estimate for the build cost is to take the floor area of your extension (width x length) and multiply by £1300.00
Costs for plans from an architect will differ dependant on the architect, an architectural technician will prove to be cheaper than a bonafide architect but the service you get and the quality of the plans will be compromised. Not many builders (and I include myself in this) would be overly confident in providing you with a fixed price for the work if there is insufficient information on the drawing. I have tried time and again to explain to potential customers that a little extra spent in the early stages will save money in the long run.
Building regulations is a separate entity to planning, irrespective of whether or not you need planning you will need Building Regs approval, you will have to pay for this and it essentially involves a building control officer coming out to site at various stages to approve the work, I think the cost varies from council to council but for something simple like a single storey extension it shouldn't be particularly expensive.
Planning permission is a grey area, it always used to be that if the proposed extension was below a certain area then you wouldn't need planning permission but as things change all the time a call to your council is the only way to be sure.

Best of luck.

Justin Upton


Answered 30th Jan 2012

Hello Janice,

I am pretty sure that you are even more confused than before having read all of the advice notes youve had.

The answer is simple!!!

Go to your local planning department or call them, then look on the planning portal for your local planning department and download the Provisional Development Enquiry Form.

Do a generic drawing and include design and size details and take it to the planning department.

This enquiry will cost nothing but some councils charge an £18 admin fee

You receive an answer 5 - 7 days later with directives as to what the next step is

Hope this helps

Kindest Regards

Ambassador Building and Construction


Answered 13th Mar 2012

phew !!! lol where to begin...... ummm . basically planning wont be needed as its under 25m2 could have issue with party wall act if your planning to build close to your neighbour's boundry wall, if thats the case full plans and a solicitor will need to be involved ! I don't know where you live but i offer free advice so get in touch with local builder he should offer same . regards plans if its basic extension the last 4 i've done i did drawings myself that more than kept building inspector happy ! Regards how long it will take appox 2-3 weeks so talk to ur builder first as long as he's got access to water an power shud'nt need you to be there much ! how this helps !!!!!!!!




Answered 30th Jan 2012

probably do it under permitted development ,on a job this size no point paying for an architect ,get a decent structural engineer to do calcs and submit basic floor plan of your requirements ,THEN get a builder round to quote,it is not fair practice to get builders round before you have these details as he will just have to come back again when you do have them as he needs these and a detailed scope of works required to give you an accurate quotation


Answered 30th Jan 2012

Hi log on to you local council planing site for lots of info, if you were to use us we would offer the services of an Architect who would advise details. Costs for drawings start at £400.


Answered 15th Aug 2012

egardless of size, A & K Architectural Services work hard to gain a strong understanding into the development you wish to pursue and then advise how to achieve your vision in a cost effective manor that meets all of the discussed objectives.

Our designs are carefully considered around your needs and we believe that a strong company client relationship makes for a successful and fulfilling planning application, therefore we are always very open to your thoughts and always keep our initial drawings open to adjustment.

Once a design is agreed upon we will then manage the project on your behalf, keeping you fully informed of progress at regular intervals.

We believe the planning stage of your development is the most critical and in the long run the creation of comprehensive plans will save you from frustrations and extra costs in the building stage.


Answered 8th Nov 2017


Lots of answers to your questions here and many of them provide a good point of view. To clear any issues you have the best idea is to arrange a free phone call for advice from an architect who would be willing to come out and see you to discuss ideas and provide you with guidance from design through to build. Thanks and good luck


Answered 10th Mar 2018

You pose a lot of questions. When you are this worried get yourself on the phone to a nice person at the council and fill yourself up with knowledge and the laws. I was surprised to read that you were going to use an architect, but in the long run you’d be doing yourself a favour. Alternatively an engineer can do this for you too. Not all building companies understand the laws here, so I’d choose wisely.

You shouldn’t need to be on site all the time. But you may want to secure you’re stuff none the less!!
Best of luck, it’s a big job but if you get a hard working team, who’s organised you’ll have it done in no time.
Utilities have to be considered though. Where are your mains pipes, gas etc. An engineer is able to help with all of this, before you spend out on big fees!! You can get drawings from a building registration site. All purchases and leases when registered have plans you can access.


Answered 10th Jan 2021

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