Before you start calling builders and the architects, you need to calculate roughly how much an extension will cost. Here’s a guide to the most important costs involved, so that you can start planning the costs of your dream conversion or extension.

Do extensions increase property value?

One of the reasons you might want an extension is to increase your home’s value. If this is the main reason, always find out in advance whether this really is the case. Estate agents are a great source of information on things like this.

Typically, extensions will increase the value of a property, but ask a local estate agent first to double check. Often it depends on your property type, location, typical buyer and other factors.

If your neighbours have had some work done that is along the same lines as what you are looking for, they should be your first port of call. Ask them about the costs involved, including any extra costs that they found and did not budget for.

Typical costs for extensions

A good starting point is to consider the different types of extensions and the typical costs per square metre. This should provide you with a good general overview when starting to plan your extension.

Here are some basic costs to keep in mind are:

  • General Extension can start from £2,000 per square metre
  • Refurbishments begin at £1,000+ per square metre
  • Loft Conversion often come in at £2,000+ per square metre
  • Basement Conversion are frequently £3,500+ per square metre

Calculating cost by property type

The type of property you own will have a big impact on prices. Generally speaking, if you want to build an extension onto an older property, it will usually cost you more. This is because older properties often present challenges that you might not face with new builds.

The plumbing and electrics might be out of date on older properties, unsafe materials like asbestos may be present, and finding the right materials can also pose a challenge.

If you are converting a semi-detached property, the issue of party walls comes into play. You will need a party wall agreement in place, and that will mean an additional cost that could be in the region of £1,000.

loft conversion twickenham

Specifications of work

Small extras can quickly add up. For example, you might see a tile you really like that only costs an extra 25p per tile. When you buy large quantities of tiles however, the impact on the overall price can be dramatic.

The types of doors (bifold, French doors, etc), flooring (hardwood, stone, etc), hardware (brass, stainless steel), and many other details will all affect the overall price.

Larger decisions will also have a big impact. The type of roof you want (flat, pitched, etc) can change a price considerably.

You might even need to hire an architect at the start of the project, and if so this will add on a significant cost to the project.

Land issues

Where your property is located will also have an impact on the price because there may be issues that affect building work.

These could include conservation issues that restrict what you can do. The soil type could cause a problem by causing difficulties with the foundation. These are all important factors you will need to plan for.

There could also be logistical difficulties depending on your location. If there are transport issues to consider, your contractor will probably add on an extra cost for these.

loft extension twickenham

Do your maths before you start work

Renovating your home is exciting, and you may already have an idea of your dream renovation. But don’t jump in before you have a clear idea of the costs involved. Plan carefully, get a clear idea of your budget and know exactly how much you can expect to spend before you get started.

And remember: always budget for a bit extra once you have done your sums. Things often crop up and can add on extra unplanned expenses, so it’s always wise to expect the unexpected.

Ready to get started?

As you can see, a property renovation is a big project. We can help you every step of the way, from ideas and planning through to execution. So let us know if you’re thinking of renovating your property, and we’ll make sure you make it a success.

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