Expert advice - planning permission

Planning permission is one of the most daunting parts of any major project in the home, particularly if you haven't been through the process before. We catch up with The Extension Experts, a London based company who specialise in planning permission and building regulations, who fill us in on everything you need to know.


Love Renovate: What are the main stages in the process from a client’s initial contact to the builders starting work? Do these stages vary with the type of work being done? 

The Extension Experts: Our process typically involves an initial consultation with the client at their property in order to discuss their plans, and to look at any other options that may be available. This also gives us an opportunity to take a look at the building and to best understand what it is the client wants to achieve from the project.

Following that, a measured survey is carried out in order to prepare the existing drawings necessary for planning which include plans, elevations, and a section through the building.

From the initial discussions with the client we would then prepare the first draft of the proposed scheme. Once the first draft is complete we present it to the client and agree any revisions.

Changes are then made until the client is completely satisfied, and we then prepare all the other documents necessary for planning and prepare and submit the application online for them.

In tandem with the Planning Application we prepare drawings for Building Control.

The planning process typically takes 8 weeks and once planning has been approved the client has 3 years to start the work.

In terms of sourcing a builder, it is always useful to go on recommendations. For a simple project, such as a house extension, the builder will typically be able to provide you with a cost for the works based on the drawings and construction notes that would have been prepared for Building Regulations.

With different types of projects there are small differences, however the general process on a domestic architectural project tend to remain fixed whether it’s an extension or a new build, however the amount of work entailed changes significantly depending on the size and complexity of the proposed works.


Love Renovate: What are the lead times involved in the process? 

EE: On a simple extension, once the measured survey has been carried out, preparing the existing and proposed drawings should take between 2–4 weeks, though this can vary depending on the complexity of the project. Revisions could take another 2-3 weeks.

So, for a typical project that runs smoothly you should allow around 4 – 8 weeks up to the planning application being submitted. This can be shorter (say 3-5 weeks) if there are few revisions and the project is simple.

Of course, this is just a guide and the length of time required to prepare the planning application is entirely dependent on the complexity of the project and the client’s programme and can be as little as 2 weeks, or many months.

Once submitted, the statutory period the planners have to make a decision is 8 weeks. If approved, you can then start the work immediately subject to any other issues (i.e. Party Walls).

The lead in time for your builder should typically be a couple of weeks for an extension.


Love Renovate: What do I need to have considered/prepared before starting this process? 

EE: Assuming you have already identified the reason why you want to build an extension and are set on doing so, you will need to then think about what you want to actually achieve, and how you will finance the build.

Most people have a reasonable idea, often only in their heads, about what they are planning to achieve. Whether this is a single storey extension, a loft conversion, or a new build. This can be outlined before you start, and once you get an expert on board they will be able to firm up your ideas and turn them into something deliverable.

The most important thing to consider is of course finances. It can be very stressful to have an incomplete build so make sure that before you start building you have the money in place.


Love Renovate: What are the common issues to look out for? 

EE: You should be aware of any listing that the building may have, as well as if you live in a Conservation Area as these will both have an influence on what you can do to your property. If you live in a Listed Building you may need to apply for Listed Building consent as well as planning consent.

Another often overlooked issue is the Party Wall (etc.) Act 1996 which applies to a large proportion of extensions (I would say at least 20%). If you plan to do work to a party wall, excavate near another building, or build on the boundary line then it may apply to your extension. This can affect your programme as you will need to serve notice on your neighbours which can delay a project by two months or more. It can also add thousands of pounds to the cost. So, get expert advice on the implications of the Party Wall Act early on.


Love Renovate: How many sets of drawings are needed and do you need different drawings for the different stages? 

EE: The majority of planning applications these days are submitted online. However, if you choose to submit your application by post you will need 4 copies of all documents submitted; the original, plus three copies. You will also want to keep a copy for yourself.

As the project progresses the drawings will become more detailed. Planning drawings are only really concerned with the aesthetic and mass of the building. Building Regulation drawings will look at how the extension is constructed, including build-up of roof, walls, and floor. The Building Regulation drawings will be annotated and make reference to any drawings and/or calculations provided by the Structural Engineer.


Love Renovate: Are the drawings suitable for the builders to use or is there anything else the builder needs? 

EE: All competent builders should be capable of pricing and constructing your extension from the Building Regulation drawings and construction notes, as well as the Structural Engineer’s calculations. It is not recommended to use solely the Planning drawings as they only provide limited information and no construction / structural information.

An example of building regulations drawings


Love Renovate: Approximately how much should I budget for professional fees to consult, draw up plans and submit planning permission and building regulations? 

EE: For an average extension with a build cost of around £30,000 - £40,000 you should budget around £1,000 - £2,500 for planning permission drawings. Some companies would include Building Regulations and structural calculations in this price, and some won’t.

If not included, structural engineer’s fees would likely cost between £500 - £1,400. This is very much dependent on the company or individual that you use.

The cost for the planning application for an extension will be £206¹ for a Full Planning Application, or £86 for a Lawful Development Certificate, which is appropriate where you think you may not need planning permission but want to make certain.

Building Control fees are around £300 - £900 depending on the size of the extension.

Other things to consider are utility connection charges which typically are around £400 - £800 per new utility service such as water or gas.

Also, the Party Wall Act² can add a large cost. We would recommend budgeting about £900 per neighbour for this.

So, for a small extension we would recommend budgeting around £2,000 - £3,500 for professional fees and application costs (this doesn’t include Party Walls or any other specialist surveys i.e. acoustic, Flood Risk Assessments, etc.). For something bigger this could be considerably more.


Love Renovate: Is there anything else I should be aware of? 

EE: On most extensions things are reasonably straight forward, but some other things that you may want to consider include:

Is there a change of use? If you are converting to flats, or changing the use of the building then you will need to apply for a Change of Use Application. This is a different type of planning application. If you think you might be changing the use then you should review the planning “use classes” to check.

If you intend to install air-conditioning, you may need to get an acoustic report carried out.

If you plan to develop a new property you should also give consideration to whether the property has any flood risks as you will likely need a Flood Risk Assessment carried out.

You should also be aware of any substantial trees on the site, as well as bats and newts which can cause real issues if they are not identified early on.

If you aren’t sure, an expert will be able to advise you on any additional requirements for your project.


¹Note these are the cost in England and they vary slightly throughout the rest of the UK.

²The Party Wall Act only applies in England & Wales. In Scotland and Northern Ireland, boundary rules apply.

Published: September 5, 2018

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