Things to Consider When Planning A House Extension

If you desire more space and you feel that moving is not an option, the easiest way to acquire this additional area is to extend your existing property. There are only two real ways of doing this which is going up into the loft space or extending the current dwelling footprint. We will only talk about the latter as the loft conversion is discussed in another article.

An existing property can be heavy modified internally to help incorporate the new extension and extra living space that you require and if feasible rooms can be completely altered to suite, an example of this the kitchen could be relocated to incorporate an island and create an open plan feel.

When assessing whether the property is suitable for your extension these are just an example of a few things that you must consider: –

  • The garden space that you have and is it sufficient in size, as this is the space your house extension will occupy.
  • Effects on neighbouring properties i.e. will it be very close to their house, if it is then how will it impact on their light and privacy? If you must build right up against a neighbouring structure you may need a party wall act agreement!
  • How the proposed home extension will influence your existing structure i.e. will it block out windows etc.
  • What is the lay of the land that you will build on, if the land is particularly sloped you may have a lot of masonry to get it level with the existing house which will increase build costs.
  • Are there any services i.e. drainage, main sewer runs that will need relocating before the extension is built?
  • How will the new home extension be used; will you have to sacrifice another room to gain access to it. If you intend to have an additional bathroom is it feasible due to drainage falls and location of sewer.
  • Are there any trees in close proximity; as these may have major effects on the foundation design.
  • Is the area a conservation area or does it have any restrictions on what you can build.

Preparing The Groundworks for a House Extension

Any major building work may feel daunting if you are not used to the process, however in most cases it is quite simple and it should not be something that you should be off putting, the most important part is having the right team in place who will guide you through the process.

Generally, the biggest risk for any house extension is the groundworks as this element is an unknown entity and cannot be truly uncovered until excavations commence however, with proper due diligence you can minimise the risk.

Your contractor should always excavate a trial pit to locate the house footing as this will determine the depth you will have to go to for your extension foundation. It is also essential to assess the drainage before any works are to be undertaken. These two simple steps will help ensure that you have as much information available as possible before the work commences.


My personal experience is that you would be very unlucky to have any major problems during groundworks, yes we have had occasions where there has been issues unearthed that has had to change the design of the foundations, however that is a very small percentage!

Once everything is out of the ground then the process is far more straight forward, this is one of the most exciting parts of the build. When you see the walls starting to be built it gives you a feel for the size of you new rooms and this stage (on an average size extension) can be a rapid process, in a short period of time the structure can be a water tight shell.

The aim would always to do any internal alterations once the extension is built this will minimise the disruption to the client, unfortunately this is not always possible, however it is usually the case. How big the internal renovations are to the existing house will also determine if you will need to move out. If every room is to be affected by the build then it would be advisable, equally if there are only a few rooms going to be affected then it may be possible to stay.


It is very important to choose your design team wisely as this is such a crucial component that should never be over looked. The designer you choose can have massive consequences on how successful the build is, after all they will be the ones who translate your ideas into a workable design, guide you through all the planning applications, and ensure that all the current regulations are adhered to.

The more information that you have personally as a client should help you to feel more at ease in the decisions that you have made for the project, and furthermore it gives the building contractors a solid base to submit an accurate tender. Once you have allocated the successful contractor to perform the works, they will also have the benefits of well thought out construction drawings, which should in turn make the whole process run a lot more efficiently and hopefully reduce the risk of any additional charges caused by unforeseen items.