Adding more space has the potential to transform your home and how you live in it. But when it comes toย building an extension, it’s important to weigh up the pros and cons of a single versus two-storey extension.
Whatever yourย extension idea, the addition will give you extra square footage to help ease space pressures on your home. If you work with a skilled architect or professional designer, a carefully conceived extension could also enhance your propertyโs aesthetic wow-factor, as well as increasing its resale value. But while aย double-storey extensionย can be more cost effective than aย single-storey extension, is bigger always better?
An extension project is a major undertaking, so itโs important to weigh up whether a second floor is essential to achieve your project goals before diving in. We spoke to the experts to find out what you should consider when it comes to the size of your extension, whether a two-storey addition is always a good idea, and ultimately how you choose the right size space for your home.
What should you consider when choosing between a single and two storey extension?
Though a two-storey extension is generally more cost-effective than a single-storey extension, itโs still a bigger commitment in terms of the overall construction budget and how long it takes to build. So, before dreaming up your ideal two-storey design, work out whether that additional level of accommodation is essential to achieve your goals.
Ascertaining what your current property is failing to deliver is a useful first step, as itโll allow you to work out how a new extension could address the situation. Next, calculate what your budget is and find out if there are any restrictions on your property that could limit what youโre able to build.
How much additional space you need?
Using your lifestyle aspirations as a starting point, think about the rooms youโd like to create and the relationships those rooms should have to the rest of the house and garden.
Price
The amount youโre able to spend on your extension plays a crucial role in determining the scope of the project. The overallย cost of an extensionย depends on a variety of factors, including how much floor space youโre looking to add, the complexity of the design and whether youโre adding a kitchen or bathroom, not to mention the level of finish youโd like.
Planning/Permitted Development rules
You need to think about what size extension you can build without planning permission, and this may influence your choice. It is possible to create a two-storey extension under Permitted Development rights without the need to apply for formal planning permission providing certain conditions are met. However, if youโre looking to make a design statement, you might find the required design parameters for PD limiting. Plus, if you live in a designated zone, such as a conservation area, your build could be subject to additional stipulations.
Design considerations
While a two-storey extension has the potential to create extra space, donโt forget that putting an additional floor on top of a single-storey structure will limit the possibility to introduce rooflights an important consideration if a light-filled kitchen-diner on the ground floor is at the top of your wish list. Possible solutions include a staggered design, with a smaller structure on the upper level, which leaves space for overhead glazing above the ground floor. You could also fit larger windows and glazed doors at ground level to invite plenty of sunshine in.
When planning your project, make sure you consider theย extension design features that are worth the money. This can be really useful when you’re trying to establish the budget for your project too.
Time
A single-storey extension tends to be the quickest option for a straightforward design, expect construction to take between two and four months. A two-storey extension will take longer set aside four to six months as a minimum.
Projects that include a kitchen or bathroom have an added layer of complexity, so will take longer. Any extension that involves significant remodelling work or detailed, bespoke elements will take longer, too.
Construction logistics
If youโre doing a single-storey extension, you may be able to seal off the construction area on the ground floor to continue living in the property as the work is happening. This becomes more challenging if youโre creating a double-storey structure, as youโre dealing with disruption in more parts of the house.
If you do need to move out at least for the most disruptive parts of the build rental costs should be factored into your overall project budget.
Value added
Theย value an extension addsย to your home is determined by supply and demand in the local property market. If you live in a rural location or have more space, it may be better to extend outwards rather than upwards.
However, in dense, urban areas where space is limited, the addition of an extra bedroom or bathroom via a double-storey extension could enhance your propertyโs value significantly providing the footprint of the extension doesnโt gobble up too much precious outdoor space. Speak to a local estate agent to get up to date advice.
Why are two storey extensions more cost-effective?
The answer to this question comes down to which parts of an extension are most expensive to build typically, the cost of the groundworks (excavation, foundations, floor slab etc), plus the structural and external envelope.
So, even if building a double-storey extension results in a lower per m2 construction cost across the whole project, an extension that provides significantly more floor space will still cost more in total. Additional items to consider for two-storey extensions include the cost of scaffolding. Plus, access can become more difficult the higher you go.
If your ultimate goal is to build a two-storey extension, but you donโt have the funds to tackle the whole project in one go, consider splitting the build into two phases and building one storey at a time. Weโd advise you to make sure the foundations and structure of your single storey extension are designed to take a second storey at a later date, should you ever need.
So, should you always opt for a two-storey extension?
Not necessarily it all depends on the must-have vs desirable features laid out in your original design brief. For instance, if the upper levels of your house already provide enough living space for your family and your main aim is to create a sun-soaked kitchen-diner, upgrading from a single to a double-storey extension may not be worth the additional expense.
How to choose the right size extension for your home
If youโre not sure how to determine which type of extension will deliver the best results, the advice of a skilled and experienced professional will help you sift through the unique details of your project and come to a well-informed decision.
Remember, the second floor of the extension can always have a smaller footprint than the ground floor. Larger is not always better, Stepping the extension in at the second floor can be beneficial for the budget and planning process.
