While it may be lawful to agree on an extension orally and then confirm it in writing by email or other methods, we would highly advise local planning authorities to acquire the developer's formal assent to any extension. This can be done by including a clause in the development consent order (DCO) requiring the developer to give their written approval for any subsequent extensions.
If the developer fails to give their consent then the planning permission will no longer extend to cover any further work on the site. The same applies if the developer objects to any part of the DCO; for example, if they do not want any alterations made to the roof shape or height of the building. If this happens then the developer can apply to the local planning authority for a variation of the DCO so that they can continue with their project.
It is important to note that while the developer can object to parts of the DCO they are still required to comply with all of its conditions unless they can show that they are exempt from doing so. For example, if there is a requirement in the DCO for the developer to provide affordable housing then they cannot simply ignore this condition and refuse to provide any homes.
The best way for developers to avoid any issues with future extensions is to get agreement on any extension(s) in advance with a plan signed off by both parties.
The simple answer is no; you will need to obtain building control clearance at the absolute least, therefore you cannot build your expansion totally without authorization. However, it may be extremely simple to get and will not prevent you from getting started (see below). Planning and freeholder consent are the two major permissions to consider. Other necessary permissions include parking and traffic permits.
It is important to understand that building regulations exist to protect people's safety and property values. If the work you want to do doesn't comply with these regulations, then you should not do it. For example, if you want to build a studio apartment block, you must ensure that the foundations are strong enough to withstand the loads imposed by the additional floors that you intend to construct. You can do this by including load-bearing walls or columns. Otherwise, people could be injured or damaged properties.
In most cases, you will need permission from your local council to build anything other than an accessory dwelling unit or granny flat. Some councils may also have specific rules about how high you can build on a plot of land. Make sure you know these restrictions before you start planning your project!
If you want to build a new house, then you will usually need planning permission from your local council. There are different types of plans that you may need to submit while applying for planning permission. These include architectural drawings, structural assessments, environmental impact reports, etc.
Extensions In most cases, a house addition or extension* is considered approved development. As a result, you won't have to go through the extra effort of obtaining planning approval as long as your expansion is no more than half the amount of land around the original house (curtilage). If the addition takes up more than half the total area, then you do need to get approval from an authority called a "planning body". These can be local councils or their equivalents. The decision about whether to give you approval will be based on policies adopted by those bodies. They may decide that any increase in floor space is too great, or that other factors such as road access, parking, etc., are affected by the proposal.
If you already have planning permission for the original building, you can usually use it again to extend into a first-floor apartment. You'll just need to make sure that the extension does not affect the cillity line or exceed the percentage of freehold/leasehold property that can be developed without further planning permission. If it does, then you would need to apply for further approval.
It's important to remember that planning laws differ between countries. So if you are planning to build an extension in England then please check with your local council to see if they require formal planning permission for first-floor extensions.