House Extension in city

The holy grail of home extensions is basically the need for additional space for living as well as leisure. However, before commencing your home extension project, you’d probably want to know just how big your new building can be. In this article, you’ll find the answer to this question which is also frequently asked by many other home or property owners in the UK.

Besides your budget, there are two other major influencing factors that can determine just how much extra room that can be added. These factors include whether you wish to carry out the extension project under Permitted Development rights which is usually for a smaller project or you’d prefer to opt for a larger project which is covered by Planning Permission.

Apart from the limitations in the size of an extension under Permitted Development, the extensions are also a lot more affordable and consumes less time when compared to the extensions under planning permission. So what exactly is the size limit for an extension under Permitted Development and the ones under Planning Permission?

For a single storey extension, the maximum size that can be constructed without having to submit an application for Planning Permission includes:

• An extension should have a maximum length of 6m, if you reside in a terraced home or a semi-detached property.

• Extensions for detached properties can have a maximum length of 8m.

• The extension built must not go beyond half your garden’s area.

• The extension should have a maximum height of 4 metres, but in the event whereby the extension is situated within 2 metres of the boundary of your property, it should not exceed a height of 3 metres.

• The extension should not be higher than the highest part of the existing house’s roof.

If you’re considering adding a two storey house extension, then setting a budget for this project would be a great way to get started. Similar to a rear extension, a two storey extension usually leaves the rest of the building needing some work and, due to its size, this may imply the re-development of the entire house - which is why they can be very costly. Some of the other influencing factors that can have big impact on a two storey house extension cost includes: your location, the size of the build, complexity of the design ( anything beyond the standard build will normally require more expertise and time), the glazing to be incorporated ( the more the glass used in the project, the more the material cost), as well as the team used.

Generally, when it comes to extensions, the major part of the expenses will be made on the build of the project. This is because it doesn’t only cover the material cost but also the contractor’s overhead as well as the daily rates. At this stage, the extension prices can be determined by the standard of the work that’s being done.

For a fairly average room size of about 18 square metre, the two storey extension should cost within the range of £2,500 to £3,000 per square metre - with the range being determined by the finishes incorporated. Therefore, a two storey extension of about 18 square metre should cost within the range of £45,000 to £55,000. However, this is with the assumption that there are standard window sizes, bathroom suits are modest, and without any need for any purpose joinery or glazing. If you wish to include all these extra features you’ll also have to pay more to make the total cost between £70,000 to £80,000.

If you’re planning on adding a house extension to your property, you’d probably be worried about whether or not your proposed extension would require a planing permission. Well, it may be relieving to know that not every house extension project would require a formal consent, and in fact, several extensions are covered by the permitted development rights. Not only can this save you a considerable amount of time especially at the project’s planning phase, but it’ll also save you money on the application fee. In the UK, single storey extensions to the house’s rear can be 3 metres deep for both semi detached houses and terraces or 8 metres deep for detached homes.

So how do you know when you’d require a planning permission for your home extension? Well, if your extension plan fits these criteria explained below, then your project is most likely going to be allowable as a permitted development.

• Extensions, which includes previous additions, must not go beyond half of the original house’s total surrounding land area.

• The main elevation, or side elevation where it fronts the highway, must not be extended forward.

• For single storeys, the rear additions must not extend more than the original house’s rear by more than 3 metres in both semi attached homes and terraces (4 metres for detached houses).

• Extensions to the side must be a single storey with a height not exceeding 4 metres and not going beyond 50% of the original house’s width.

• Extensions hat within 2 metres of a boundary should have a eaves height not more than 3 metres.

• Multi storey addition must not extend beyond the original house’s rear wall by a maximum of 3 metres or 7 metres of the boundary opposite the rear wall.

• Permitted development rights do not apply in listed buildings or designated areas.

There are many different types of extension. For example, you could install an orangery, flat or pitched roof extension, over-structure extension, single or double storey extension or a glass box extension. Which one of these is most suitable will depend on your existing property.