Planning permission
In many cases you will be able to plan a house extension without applying for planning permission but for more significant extensions you will probably need to submit a planning application to obtain the consent.
It is recommended to seek advice from your architect if you are not sure about which category you fall into.
For instance, a single-storey rear extension is allowed to be up to 3m deep for a terraced house, or up to 4m deep for a detached house subject to a neighbour consultation scheme.
In the UK, these regulatory limits have been extended to 6 or 8 meters.
In this case your project falls within Permitted Development rights so you won’t need local authority planning consent.
When you submit a Permitted development application, the Council will consult the owners of adjacent properties (neighbour consultation scheme) and would then carry out an assessment of the impact of the proposed property extension only in the case that your neighbours object to your proposed development.
If you are required to apply for planning approval for your extension, it is important to bear in mind that the way in which planners approach planning permission can be very different depending on which council is carrying out the work.
In general, some of the main concerns for planners are related to overshadowing and overlooking neighbouring properties.
They will have to decide whether these factors have a significant and detrimental effect to the neighbouring.
Making this assessment can be quite subjective.
Conservation areas and listed buildings
If you are planning a house extension in a Conservation Area you will probably need planning permission.
Each local authority has its own policy so it is best to contact your local conservation officer first.
Also, any alterations to a listed building, including internal ones, need approval. To prevent the loss of character of the listed building, any new house extension needs to respect the appearance, materials etc. of the original house.
Build near or over a Public Sewer
Often sewers run within private land and they can usually be found at the front, rear or side of the property. If you are planning a house extension it is important to assess the drainage situation in your property and if you find a public sewer in your garden you will need to ask permission before starting the building work.
For more information please follow this link.
Structural engineer
Whether or not you will need a structural engineer depends on the nature of the project. If you are planning a house extension, loft conversion, removing a chimney breast, removing internal walls and many other cases you will definitely need a structural engineer to do all the structural calculations.
Party wall agreement
If you are planning to build a house extension or carry out any building work near or on your shared property boundary you will need to notify your neighbours of your intentions by serving a notice under the Party Wall Act.
If you can’t come to an agreement with your neighbours you need to appoint a party wall surveyor that will prepare all the legal documents for you.
For more information please follow this link.
Construction, Design and Management (CDM)
Homeowners are now responsible for the safety on their building projects. Complying with CDM 2015 will help ensure that no-one is harmed during the work, and that your building is safe to use and maintain while giving you good value.
Effective planning will also help ensure that your work is well managed with fewer
unexpected costs and problems.
For more information please follow this link.
Building Regulations
Once you have received the planning permission approval for your house extension, the next step is making sure you comply with Building Regulations.
Your architect will provide you with a set of construction drawings that will be used to gain Building Regulations approval.
These drawings are considerably more detailed than the design drawings and will contain detailed section drawings, construction materials, electrical and drainage layouts, etc.
The drawing package will allow contractors to provide accurate tenders to complete the project and be used on site when building work begins.
