What are the first steps to building an extension

Your Extension - Starting Out

So, you are planning to do a home extension on your property. But where do you start? This blog post will guide you through those initial stages of getting to a builder on site digging your foundations.

The first thing you need to do is think about your space priorities. Is it just a new kitchen you need? Or do you need a Kitchen Diner with an New Open Plan Living room, utility and maybe a downstairs bathroom?

If it is the latter, then you will likely need to extend more generously and over 3m. The more space planning you do, the easier it is to understand which type of planning process you need.

Check out our Case Studies for some design inspiration.

The second thing you should do is consider the cost of a rear extension and budget how much you can put towards the construction. A good estimate for your extension cost is to multiply the square meter area of the proposed extension by £2500. Therefore, if you have an extension which is 5x4m - 20 square meters your extension would roughly cost £50,000. You should also factor in any potential VAT which would add a further 20% to the costs. This estimate doesn't include the internal works, for example, if you were fitting a new kitchen. Depending on your specification, it could be £3000 per square meter if you are having a high-quality specification and finish. On average you should have roughly £50-70,000 for a typical 3m single storey rear extension with the full internal fit out.

How long will my rear extension take?

A typical timeframe from engaging your architectural designer to completion for your rear extension is 9 months - 1 year.

• Architectural Planning & Design Drawings (2-4 weeks)

• Planning Submission & Permission (8-14 weeks)

• Architectural Building Regulation Drawings (2-4 weeks)

• Builder Invite to Tender/Cost (2-4 weeks)

• Construction (3-6 months)

What are my permitted development rights for a rear extension?

Your permitted development rights for your rear extension will depend on your property.

For Terrace & Semi Detached properties you can extend up to 3m and for Detached properties you can extend up to 4m. Anything above this would not fall under permitted development and would require full planning permission.

For all of these types of property, the extension must take up less than 50% of the size of the land around the original house. It must also be less than 4m in height, or 3m if the extension is within 2m of a property boundary. The eaves and ridge of the extension must be no taller than than the existing house and matching building materials to the existing house must also be used.

In summary:

• Extension must take up less than 50% of the size of the land around the original house

• Must be less than 4m in total height (or 3m if the extension is within 2m of property boundary)

• Eaves and ridge must be no taller than the existing house

• Must use similar building materials to the existing house.

Do I need to submit drawings to the council for permitted development?

We would advise that you submit the drawings to the council under a Certificate of Lawfulness Proposed Use. This will cost £106 for the submission. The council should then grant you a certificate of lawfulness within 6-8 Weeks.

It is advised to get a certificate of lawful development, should you come to sell your property you can hand this document to your solicitor to state you have completed the extension under permitted development.

However, you do not have to submit drawings for your rear extension as long as you comply with the permitted development guidelines.

What is the difference between Prior Approval and Permitted Development.

In essence, Prior Approval is an addition of your permitted development right that is subject to neighbour consultation and comments.

For example, if your property is a semi-detached or terrace you can extend 3m under permitted development. But under Prior Approval you can extend up to 6m at the rear. If your property is detached you can extend up to 4m at the rear under permitted development, but up to 8m with prior approval.

Prior approval allows the local planning authorities to consider the likely impact of the proposal, regarding factors such as transport and highways.

Work must not commence on the development until the local planning authority has issued its decision. This usually takes around 8 weeks from when the application is received, however, this can be extended depending on the type of proposal. you could be required to submit more information on a variety of aspects from the proposal such as:

• The design and external appearance

• The transport impacts of the development

• Flooding information.

Common Misconceptions With Permitted Development & Prior Approval for Extensions.

Prior Approval is often put under the same rubric as permitted development. But they are assessed differently by the council. Prior Approval Applications allow you to extend at the rear by double the amount you are permitted under usual permitted development rights. If you extend further than your permitted development rights (over 3/4m) you will require a application to be submitted so that the neighbours can comment. This is Prior Approval.

You cant combine permitted development rights with a prior approval application. For example, you might want to do a side extension under permitted development and a 6m rear extension. In this instance, you should submit for a permitted development certificate of lawfulness for your side extension in a separate application. This is because Prior Approval Extensions will be assessed under their own merits.

The Prior Approval Process

• You will need to complete a "Notification form for a proposed larger home extension"

• Your immediate neighbours will then be contacted and given at least 21 days to decide if they wish to object.

• If there are no objections, as long as the extension falls within the rules, Prior Approval will be granted.

• If there are objections, the impact of the extension will be considered and it will be decided if it is acceptable and Prior Approval will be granted, or if the impact is considered unacceptable, Prior Approval will be refused.

• The refusal of Prior Approval can be appealed and a decision has to be made within 6 weeks or it will be automatically granted.