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 about to start your house extension project and wondering how long it’ll take to complete, you’re not alone! This is one of the most common questions that’s asked by homeowners in the UK and across the globe. However, there’s no single precise answer for this as there are multiple factors that’ll affect the length of time it’ll take to complete your home extension. These factors include the size of the construction work as well as whether you’re planning to live in the house after completion or otherwise.

For a single extension, the length of time it’ll take to complete the home extension is normally up to 3 months. So let’s break this down:

As you would have expected, the first step to be taken is the preparation of the site. You start by digging out the footing and preparing the foundation which should take about 2 weeks. This is then followed by the damp course installation as well as the fitting of any drains needed around the extension which will also take a further 2 weeks.

The 5th week will be for the construction of the external walls as well as putting the blockwork in place for the provision of the cavity wall insulation. A further 2 weeks after this, will be dedicated to the installation of the roof structure and the internal walls.

It’s at this junction that you’ll call on your weather proof installer to fit in your uPVC windows and doors. Once done, the gas fitters and electricians will have to be on site to connect power to your new extension building. Subsequently, this will be followed by internal wall plastering as well as breaking through your main house. Once the plaster is dried, decorations completed and all the required furniture and units installed, the extension is ready for use.

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.

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.