Planning the build
Why build an extension?
Initial design sketches
On-line Building Regs
Meeting planners
 Meeting building control
 Planning the foundations
 Planning the floor slab
 Marking out the footings
 Damp proof course issues
 Possible drainage problems?

 Construction of the walls
 Proposed roof structure
Windows diary
 Window challenges
 Initial window plans
 Making the casements
 Making the frame
 Designing leaded lights
 Making leaded lights
 Assembling the window
 The little window

 The door frame
Demolition diary
 The demolition starts!
 The demolition continues
 Still more demolition

Foundations diary
 Foundation issues
 Drain issues
 Digging the foundations
 Rethinking foundations!
 Pouring the foundations

Floor slab diary
 Rethinking the slab!
 Floor vent extensions
 Preparing the slab #1
 Preparing the slab #2
 Pouring the slab

Walls diary
 Preparing to build walls
 Build up to the DPC
 Build the walls #1
 Build the walls #2
 The gas men cometh
 Build the walls #3
 Finishing the walls
Roof diary
 Roof structure build
 Tiling the roof
 Finishing the roof
 Finishing the gables
 Roof insulation

 Floor screed
 Shower room
 Shower room floors
 Shower room walls
 Utility room
 Utility room walls
 Utility room floor
 Finishing the windows

Project finished!
 Final inspection
 The certificate
 Final thoughts

 Twelve months on!
 Material costs
Sister sites
 House re-roof project
 Home gas usage data

 Stop paint flaking
 DIY secondary glazing


Meeting with the planning department

Whenever you think about the possibility of building an extension to your house you should always go and see your local council planning department as the first step.

Do I need to make a planning application?

I'm not sure how all planning departments operate but they will usually ask you to complete an informal form like the one shown at bottom right (click to see full size) to determine whether you actually need to apply for planning permission.

Even if you believe you do not have a need to obtain planning permission because of the scale of your development, gaining the written approval of that you do not need permission could be very beneficial later on, if you find local residents complaining for whatever reason during the build phase.

A more important reason is to ensure that you provide sufficient information so that they can make the determination quickly without having to resort to coming back to you for further information. The last thing you want is delay!

Moreover, in my experience planning departments are generally very helpful and are very willing to spend a little time sitting down with you and answering all the questions you may have and providing advice on how to proceed.

With my particular extension which is quite small I did not feel that I needed planning permission so I visited the local planning department as asked to talk to a planning officer about what I wanted to do. They will usually ask for your address at reception and will the planning officer will come out to talk with you armed with the planning request history of your property if there is any.

According to my council's guidance, you will need to make a planning application to extend or add to your house if:

  • you want to build an addition, which would be nearer to any highway than the nearest part of the original house unless there would be at least 20 metres between your house (as extended) and the highway. There are special rules for porches.

  • more than half of the garden around the original house would be covered by additions or other buildings or structures

  • your house is a listed building

  • there is a condition attached to the planning permission for your house which restricts the building of extensions or additions;

You will need to make a planning application if the extension or addition is more than the following limits on size and height. It is important to note that some buildings or structures built close to the house are treated as if they were extensions3.

How big an extension can be added?

In the case of:

  • any terraced house (including an end of terrace house or any house in a Conservation Area) you can add a maximum of 10% or up to 50 cubic metres (whichever is the greater) to the volume4 of the original house without needing to apply for planning permission.
  • for any other kind of house outside of a Conservation Area you can add a maximum of 15% or up to 70 cubic metres (whichever is the greater) to the volume of the original house without needing to apply for planning permission.
  • in all cases 115 cubic metres is the maximum that can be added to the volume4 of the original house without needing to apply for planning permission.

Preparation for the meeting

I do not claim to be an expert on planning issues, but before you go to your local council's web site and go through to the planning department's section. You will see there all the material you will need to determine whether you need planning permission or not.

I will not go into any of these issue here as you will need to examine these yourself to see what you will actually need to do.

The volume of the extension.

The guidance from my local council is shown above . These volumes are measured up to the eves of the extension and house and should not not include the roof space. Also, extension volumes are cumulative, so if you have had previous extensions then you need to add those to the volume of your new proposal.

The volume of my extension was approximately 18 cubic metres and I had previously extended my garage by 7 cubic metres making a total of 25 cubic metres. The volume of my house - calculated after taking measurements - turned out to be around 500 cubic metres. 15% of which is 75 cubic metres, so my extension falls well within the limits of not needing planning permission. This was my assumption prior to my informal talks with the planning department.

The meeting

On a pleasant day in February, armed with my sketches and photos, I made my may to my local planning office to check whether there would be any issues with my plans to build a small extension at the rear of my house.

The meeting went well. We discussed my sketches and the relation of the extension to the boundaries as any extension that is less than 5 metres from a neighbour's boundary needs planning permission I think. The only point that was raised, was that I needed to include my shed in the sketches that would be submitted with the form above as it had a volume of greater 10 cubic metres and was less that 5 metres away from the proposed extension.

I also needed to show in the sketches my previous garage extension.

Other than this, he felt that there would be no other issues and that planning permission would not be required. So, all in all, quite a satisfactory meeting.

All I needed to do was to add a few details to my sketches, complete the form above and the they would come back to me within ten days as to whether permission was needed or not.

Quite a pleasant and useful experience really! This is so easy to do - why would you not do it? But, this is often the case for some reason.

Next step

19th February: The next step is to formally complete and submit the above form together with my sketches to the council to ensure I have their agreement about not needing planning permission. Fingers crossed!

11the March: I today received a letter from the council saying that I did not need to apply for planning permission, so I can the build when I'm ready to do so.

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