Building an Extension on a House: What you need to know

Home extensions in London come in all shapes and sizes. The size, scale and type of extension that is right for you will depend on various factors. Some of these include the style of the existing property, the planning policy that is interpreted by your local council and your budget. Your reasons for wanting to extend are also important. 

Building an extension on a house is a complex job. There are multiple different trades that need to be involved at different times. For this reason, it’s important you have a home renovation specialist by your side, who can support you throughout the project and ensure everything runs smoothly. Here at Home Tales, we offer a comprehensive package that prepares you to build. This includes architectural design, obtaining the relevant planning permissions and structural calculations. If you would like for us to stay on and project manage the build through to completion, we can do so. 

We thought we would run you through some of the key stages of the process when it comes to building an extension on a house. These are fairly generic items, and they aren’t necessarily relevant to all projects. If you would like to discuss your project in more detail, book a consultation with our team and we can go into specifics and confirm what will be and won’t be needed. 

Step 1 – Architectural Design 

You need to have the architectural design completed for many reasons. Prior to your build, your planning officer will need a clear design to make a decision on your planning application and your structural engineer will need the design to produce the structural calculations. On commencement of your build, your building control officer will need to sign off on the drawing set, to confirm building regs have been considered and met in the scheme. Your builder will also need a copy of the drawings to show them what to do. It’s also important that you see floorplans, so you can visualise how the space will look when its complete. Here at Home Tales, we offer unlimited amendments on the architectural design. We also show lots of detail on our floorplans, as we feel it’s very important that you are able to visualise how the space will work. We show kitchen outline, as well as where your appliances will be. This can be handy if you are opting for an off-the-shelf kitchen from Ikea or Howdens. We show living areas, dining tables, desks, chairs – you name it, and we will show it. We recently showed where the dog seating area would be on one of our ground floor extension designs. 

Step 2 – Planning Permission 

If you are extending your property or modifying the exterior in a significant way, you will need to obtain approval from your local council. We will identify how best to obtain this approval and advise you on whether is best achieved via full planning permission or via permitted development. Here is a great example of a loft conversion in Wandsworth we recently gained approval for under permitted development. We will then prepare the planning pack, which is a set of drawings that includes a site and location plan, elevations, sectional details and roof plans of the proposal. If you are in a conservation area or an area that is considered high risk to flooding, we will prepare additional documents, such as a design & access statement or a flood risk assessment. This will accompany the application and further support our application for development. We will then submit the relevant application on your behalf and follow up with the council at various stages to encourage a successful outcome. 

Step 3 – Building Reg Pack 

Once approval has been confirmed from your local council, we will move onto your building regulations pack. These are your detailed drawings. This pack will be requested by your builder, as it shows them what steel specification to use. It will also be requested by your building control officer, as they will want to ensure that the scheme complies with current building regulations.  

Step 4 – Finding a Builder 

Within our design package, we also include a detailed schedule of works. This is a detailed list of the scope of works that you are looking to undertake. It enables you to tender the scheme to builders and receive like-for-like quotations. Without this schedule, you would send your drawings to builders and they would return their own schedule of works. This can be confusing and makes it very hard to compare like for like costs, as everyone’s scope is different. The schedule of works puts the power in your hands – and enables you to compare costs in a clear and concise way. We have a fantastic builder who we can recommend, who you can include in your tender if you wish. 

Step 5 – Building Control 

You will need to appoint building control to oversee your build and issue a certificate at the end of the project to confirm building regs have been met. This can be done via your local council or via an independent body. Your assigned officer will want to review the drawings we have completed (mentioned in point 3), and they will visit your building site 4-5 times to check building regs are being met. 

Step 6 – Thames Water

If you are building a ground floor extension, you might need to notify Thames Water of your intention to build near their pipes. When you assign building control, this usually triggers Thames Water to send you a letter, explaining more about what they require from you. Generally, they require an application to be submitted to them, showing some details of the pipework that sits beneath your garden. 

We hope the details above give you a good idea of the home extension process – and what you need to know and do before you commence works on-site and also during the build phase. If you would like to discuss your project in more detail, we would be delighted to assist. You can book a telephone consultation online via our live diary. Alternatively, call us on 0207 043 2378 or email us at   

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