The Design Process

Planning Permission

Once you have decided to proceed with the design of a project, you will need to finalise the design details and to obtain the formal approvals required.

The first part of this process is to complete the plans to a standard suitable for planning permission. At this stage, you need not worry too much about the internal details.

The planners will only be concerned with the 'external envelope' of the building (that is, the overall size and shape and its impact on the neighbours) so make sure that you concentrate initially on this.

Check that the overall dimensions give you the sized rooms you require and make sure you are happy with the elevations.

Make sure that there is sufficient car parking provision as this can change if you are proposing to build more bedrooms.

Check that the proposed materials are clearly shown as the planners will need to be certain that the extension blends well with the existing property.

If you are planning on felling any trees or hedges, make sure these are shown on the plans.

Your designer will deal with ensuring that the plans are to the correct scale and include additional information required for the planning submission such as a location plan, block plan and a design or access statement.

Once the plans have been completed, they can be submitted to the local councils planning department for approval. Please refer to our factsheet on Planning Permission for Extensions for more information on whether or not planning permission will be required for your project.

Planning Permission Required

If planning permission is required then it is normal practice for your designer to deal with the application for you, acting as your agent. Once an application is made, it goes on the planning register and is available for public inspection. If you are submitting the plans yourself, the council application forms can be downloaded from their website together with advice on how to complete them and the councils fees. It is normally in the region of £150 for an extension planning application.

Details of materials for walls, roofs, windows and doors will need to be provided, together with a Certificate of ownership stating that you own the property (or have notified the owner if you don't!)

For further details on timescales for obtaining planning permission, refer to our Project Timing section.

Once a planning approval has been granted, be aware that it will contain conditions, one of them being a time limit on how long you have to build your proposal. This is usually 3 years from the approval date.

Planning Permission Not Required

Where planning permission is not required, we would recommend that you obtain written confirmation of this from your local planning office as it may avoid any problems when you come to sell the property. This can be done by writing to the planners or a more formal 'Certificate of Lawfulness' can be applied for which will require a fee of approx £75.00. Your designer should deal with this for you. – for more details see our factsheet on Permitted Development.

Building Regulations

Once planning permission has been granted (or it is not required), your designer will then prepare building regulation drawings and submit these for approval to the council or to an approved inspector. Be aware that there are two methods by which you may seek Building Regulations Approval - either through Full Plans or Building Notice. See our factsheet on Making a Building Regulations Application for more information on this.

Some companies/designers will submit the building regulations application whilst planning is being considered to speed up the process but you run the risk that if planning is refused you will have to redesign or scrap the building regulations drawings which would normally cost you an additional fee.

The drawings that are completed for building regulations approval are commonly known as the working drawings and these will contain all the information needed to ensure your proposal meets with the current regulations. They also need to be clear and have sufficient detail for your builder to be able to use to accurately build your extension.

Poor quality drawings will lead to problems and uncertainty when pricing the work and when building. A good set of working drawings should include the following:

• Adequate scale - whilst the council will accept various scales for the drawings, we would recommend that the plans and elevations are drawn at 1:50 scale and the sections at 1:20. This will ensure that the layouts and details are clear.
• Levels - the drawings should show ground levels correctly and any change in floor levels
• Dimensions - the drawings should be properly dimensioned so that the builder knows not just the overall size but also positions of doors and windows, internal walls, heights. It is poor practice to have to scale from the plans.
• Structural Works - the drawings should include any structural beam sizes or information supplied by the structural engineer.
• Drain inverts - the depth and route of existing and proposed drains should be clearly shown.
  

Other Approvals

You may need to obtain other approvals for your proposal and your designer will usually help you deal with these. You may need to involve your solicitor to check if there are any restrictive covenants and a party wall surveyor if your neighbour requires one.

Specification for Works

Once the working drawings are complete, we would also recommend that a written specification is also prepared for your project as this will minimize misunderstanding between you and your chosen builder.

There are many aspects of your project that will not be shown on your drawings (e.g. type of sanitaryware, ironmongery, wall tiles, etc) but these need to be defined so that a builder can properly quote for the works. The specification will also usually form part of your agreement with the builder when works commence.

Once you have received Building Regulations approval and any other approvals you may require, you can then commence building works with your chosen builder. The next section of our site provides details on the building process of a home extension.