House Extension Costs

House Extension Costs

The Cost of a House Extension

Tiny House


At some point in time, you might consider your house as being too small for your needs. Perhaps you want to prepare

your home for a new child, or maybe you’d like some extra space in your home for hobbies and storage. Whatever your needs are, getting a house extension can be a great option for space-starved households.


The other option is to move home, and for most people, that’s simply not practical or affordable. This makes the option of extending your house even more tempting, and it’s often going to be the go-to choice for most homeowners.


But how much does a house extension cost exactly? Should you do it yourself or hire a professional? What options are there for cheaper or more luxurious house extensions? In this article, we’re going to answer those questions by giving you sample quotes and estimates of how much you should expect to pay, and also detail some of the pros and cons of doing a DIY house extension and hiring a professional contractor to help you.


Let’s Start With a Basic Metric


To start, let’s use a very basic metric when it comes to how much you can expect to pay for your extension. Keep in mind that is is a very rough number and will vary depending on where you live.


£1,500 per square metre


That’s roughly how much you should expect to pay for a home extension. This is a very basic metric that most 

contractors are going to follow, and depending on the area you live in and the services being offered, you could add or remove a couple hundred. Remember, this is a very rough figure that is based purely on the size of the extension and does not take into consideration any professional fees, any planning costs, building regulation considerations and decorating. It is in our opinion hard to estimate an extension like this but can be used as a rough guide.


£1,500 per m2 is a very generous price, especially if you live in high-cost locations such as expensive parts of London. If the job involves modifying the structure of a house, such as adding a double-storey extension, then you can expect to pay around 50% more for the completed job. If it’s a simple extension in your garden or even a loft conversion, then you can expect to pay a little less because there aren’t as many considerations to the structure of your home.


Again, we can’t state enough that this is a rough figure and needs to take into consideration extra points such as adding plumbing, electricity, decorations, flooring and so on. These can add a lot of extra money to the cost of the extension, and depending on how you plan to add the finishing touches, could require a specialized contractor.


Sample Quotes for House Extensions


Below, we’ve put together sample quotes for some of the most common house extensions. This will give you a rough idea of how much you should expect to pay for just the house extension alone.


Single Storey Extension Costs


A single storey extension is arguably the most basic and straightforward extension that you could request from a contractor. It’s estimated that you could pay anywhere around £1,300 to £1,700 per m2 for a basic single storey extension. The price is going to increase in various parts of London and will decrease as you get to the outskirts.


So if you’re planning on a simple 4m x 5m extension, it will cost around £30,000. This is the price before any professional fees and also before VAT. With everything else in mind, you could be paying upwards of £40,000 for the finished product including extra fees and renovating the space as well.


Double Storey Extension Cost


As explained before very briefly, a double storey extension will cost around 50% more. This means that the price of £40,000 before will increase to £60,000, making it a very costly extension to undertake. However, it can add far more space to your home and you’ll generally get more freedom when it comes to picking the functions for your new rooms.


We can’t stress enough that these are very rough estimates, and it’s always a good idea to speak with local contractors in your area to see what they would typically charge. You should also keep in mind that the cost can increase or decrease depending on your circumstances. If you’re adding a two storey extension to your existing home, then it could be a little more expensive if the contractor needs to consider the structure of your home, get planning permission, follow specific building regulations and so on.


Kitchen Extension Costs


Kitchen extensions are a little more complicated because it’s not just about adding extra space. You need to consider things like extending electricity, plumbing and gas lines, and you’ll also need to consider decor and appliances that go with your kitchen. Depending on the location of your kitchen, the extension might need to stretch into your garden or even out the side of your home.


From a planning perspective, kitchen extensions are going to vary depending on the circumstances of your home so it’s hard to give an estimate. However, you can still follow the basic metric of £1,500 per m2. Given that an average kitchen is roughly around 3m x 2m, we can estimate that a kitchen extension will start at roughly £12,000 after including any professional fees, appliances and designs.


Bathroom Extension Costs


On the contrary, a bathroom extension is usually a little cheaper because you don’t need to modify as much of the room. However, bathrooms typically aren’t inaccessible locations where you can simply modify the room and add extra space. This ultimately means that a bathroom extension, while cheaper, in theory, can get expensive if the conditions aren’t right. Again, this is something you’ll need to contact a builder about and have them analyze the situation in your home before giving you a quote.


However, based on the average size of bathrooms and the metric of £1,500 per m2, we can safely assume that a bathroom extension will start in the vicinity of £10,000. This includes the extension, extra appliances, plumbing, finishes and so on.


Bungalow Extension Costs


Bungalow extensions are much easier to manage since your entire property is on the same level, meaning that unless you want to convert it away from a bungalow by adding a double storey extension, you can simply look at the single storey extension prices and expect it to be very similar.


Bungalow extensions are simple to perform and can add a lot of extra space to an otherwise small home. They’ll often extend into your garden, so do keep this in mind if you want to preserve backyard space for other things such as gardening or patio space.


Garage Extension Costs


Garage extensions are typically a little cheaper because the materials used are different and there often aren’t any complex building restrictions and considerations to keep in mind. As a result, you can expect a slightly lower price than the average metric of £1,500. You can expect a simple garage extension to start at around £10,000 for an average extension.


However, things get a little more complicated when the garage is underneath the second storey of your home or is directly attached to your property. In situations like this, you may need to pay a little extra because the structure will interfere with your home, making it a little more complicated to deal with. This could cause the prices to shoot up to around £15,000, depending on the circumstances.


However, for a very average standard garage extension using simple materials, you might be able to cut the price down to around £5,000 if you are only extending the garage a small amount. On the contrary, if you plan to increase the height of your garage, then you may need to add a little extra due to the structural considerations and materials used.


Loft Conversions


Unlike regular house extensions, a loft conversion isn’t so much an extension as it is hollowing out your attic and making it easier to inhabit. As a result, you might expect a loft conversion to cost less than the base price of £1,500 per m2. However, due to the building constraints and other considerations, the price can be relatively high if the conditions aren’t right and a lot of cleaning and renovation needs to be performed before you can convert the loft.


You can expect a basic loft conversion to start around £20,000 with all the professional fees and renovation included. However, converting a large loft into two different rooms and adding a bunch of extra appliances and furniture could bump the cost of a loft conversion to £30,000 or more. As with the other extensions, the circumstances of your home and the area you live in will drastically change this price, but it serves as a good base of what you can expect to pay.


Picking the Right Extension


So to summarize this section, we can see that the cheapest home extensions are ones that don’t involve interfering with the existing structure or layout of your home. Single storey extensions that protrude into the garden are cheapest because they don’t require as much planning. Similarly, garage extensions are also inexpensive.


However, once you factor in the structure of the home, such as extending a kitchen, bathroom or a double storey extension, you need to start paying more depending on the circumstances that you’re facing. Keep in mind that any extension you perform is going to increase the value of your home as well, making it a worthwhile investment even if you plan to sell your home in the future and move into a different one.

DIY Disaster



DIY or Professional Contractor?


Doing your own DIY work is popular nowadays, but a DIY home extension might be a larger project than you might be willing to handle.


The Problems With a DIY Home Extension


With these sample quotes in mind, it makes sense that people would want to consider the DIY option. However, unless you are an experienced extension builder with a lot of resources and money, it’s not a very good idea to try and perform your own DIY renovation. This is because, in addition to costing a lot of money and requiring a lot of manual labour, you also need to consider factors like soil conditions, building permissions and weather concerns.


In some cases, you’ll also need to hire a designer or architect to help you plan the entire build. This is going to add even more money to an already expensive and time-consuming project. House extensions also typically require several people to make the process smoother, and the last thing you want is to injure yourself or leave your extension half-finished for a long period of time.


If you do throw in the towel in the future, then remember that contractors will likely need to clean up the job you’ve started, especially if it’s not done correctly. This adds even more time and money to the project, and ultimately makes your initial investment a complete waste. Overall, we’d definitely recommend that you steer away from DIY house extensions and leave it up the professionals. Sheffield House Extensions can take over the whole build and make the journey pain free.


The Things You Can DIY


Instead of trying to do the entire extension yourself, you can still have some control over the project by adding the finishing touches yourself. Whether it’s furnishing the room, painting the walls or tiling the floors, you can always tell your contractor that you only want the extension build and tested so that you can design and decorate it yourself.


This is a great option especially considering you’ll be left with a blank slate on which you can work on at your own pace.


Final Words


Hopefully, this article has given you an idea of how much a house extension actually costs, how you could potentially lower the prices, and why a complete DIY solution could be more work than you’re able to handle. House extensions are excellent ways to boost your home value and add more functionality, but it’s a job that’s best left for the professionals to handle.

Please get in touch for a free quote.