How to plan your house extension project.
The vision and layout.
When it comes to house extension projects, there are a few essential steps you will have to follow. The first step is your vision of your extension, and either it is a single or double-storey extension, rear or side extension; first, you have to determine what would be your ideal layout of the new house. The most common design is to combine kitchen extension with an existing part of the house to create an open-plan space and dining area. The significant role in the design is usually glazing elements such as bifold door or skylights, so it is essential to look at your extension from natural light perspective.
House extension planning process.
Depending on the size of your extension, location and design, you may or may not need to apply for planning approval, however, in both cases you will have to process the application through the planning department in your local authority. In the specific circumstance, you may be able to get your extension approved under permitted development rights, but only if your design will meet particular criteria. To apply to your local authority, you need to provide a set of planning drawings which represent existing and proposed floor plan and elevation drawings. The planning process takes eight weeks in the best case scenario if there are no objections from your neighbours. In conservation areas, this process can be more complicated because you may have to comply with the existing style or character of the surrounding area. Once you get planning approval, then you can build your extension, but first, there are a few more things you have to take care of first.
Party wall agreement with your neighbours.
Party wall agreement is a critical aspect of the process and must be obtained before the commencement of the works. There are two ways of getting a party wall agreement, and if you are friendly with neighbours, you can do this by yourself just asking them to sign a party wall letter. Taking photos of a party wall is also necessary in case you have to determine the condition of a party wall before the beginning of the works. Having reliable documentation can resolve potential conflicts in the future during or after your house extension process. Another and more expensive way is to employ a party wall surveyor. By law, your neighbours have rights to retest party wall surveyor at your expense for theirs and your side, which could be very costly.
Thames water agreement.
Sewer position is another essential information that you would need to confirm before the commencement of the works. You need to check for public sewer and notify Thames water to determine if you need to obtain build over agreement or not. Any other drain pipes which are not shared with any of your neighbours are considered as private drains, and in this case, Thames water has nothing to do with it. If the situation with the drainage is unclear, you can call a local specialist to get drains CCTV survey.
Building regulation and structural drawings.
When it comes to the specification of your building, it is essential to get the right design in the technical aspect of the construction. Building regulation drawings are the instruction and drawings in line with current regulations standards. For example, external walls and roof structure must be insulated with the suitable materials that are meeting the construction norms otherwise if your building fails to comply with building regulation your extension will not be signed off by building control. Structural drawings and calculations are different from building regulations and must be explicitly designed by a structural engineer. When it comes to openings, removal of load-bearing walls and building structural elements is critical to get consulted with the engineer before the commencement of the work.
On-site building control.
The final thing to do before you start the extension project is to notify building control, and this needs to be done at least three days before commencement. There are two choices, private and council building control services and generally private services could be more expensive but also more helpful. However, there is no rule about this, and dealing with private inspectors could be challenging at times. At the end of the day, if you comply with building regulation, there is no problem but is a good practice to notify them in advance about every site visit they need to attend.
Building work and contractor.
Now when it comes to do the work and build your extension, it’s time to appoint the right person for the job. Best advise, check the company's history and reference of previous clients. Get at least three contact details and visit them if possible. Very important is to express your expectation clearly and agree to specification to avoid potential disagreements. For example, to make sure the contractor included floor finishes or tiles in his estimate. Fixed-price contracts are the best with the milestone method of payment to make sure you always pay for the work that was delivered. If there are any additional cost to the original estimate, make sure you obtain the quotation first and not after the job is done because surprises like this could lead to unpleasant conflicts.
Useful links and information.
Planning portal and decision-making process:
Party walls and building work
Building over or near a sewer
Building regulations approval