How to roughly price an Extension
It’s wise to establish a realistic budget as early as possible. This allows you to have a meaningful conversation with your architect, ensuring plans are achievable. But to answer ‘How Much Does An Extension Cost?’ can be daunting if you don’t know where to start.
Estimating using cost metrics
Although building costs can vary greatly (depending on size, finish and complexity of the interior fit out) – estimating a ballpark figure is fairly straightforward. You can gauge a rough cost of a single-storey home extension using cost-per-square-meter rates.
There are three principal stages to consider in your estimate: construction, interior fitout and optional upgrades. Each has an associated rate, shown below.
Example: 24M2 flat roof extension
A 6M x 4M (24M2 area) extension like the one pictured is a popular choice, since structures less than 30M2 do not require planning permission.
We have broken down the typical costs for each stage below.
Option 1: Structure only
Opting for the basic structure only is the most economical choice and allows for a staggered approach, with fitout arranged by you.
24M2 = £36,000 – £42,000
Option 2: Interior fitout
Fitting out the structure to a high living standard allows you to enjoy the new space straight away. Added to construction cost.
24M2 = £12,000 – £18,000
Option 3: Include upgrades
Thinking ahead and adding luxury items during the build will maximise your living experience – and is far cheaper than retro-fitting.
24M2 = £6,000 – £12,000
Total Extension Cost
Clearly, there is a lot to consider when planning your build, but using this approach is extremely useful to quickly get a feel for the costs involved.
Total = £36,000 – £72,000
Final thought – Contingency
There is always the possibility of unforeseen problems. For example, obstacles can sometimes arise when digging foundations, and economic changes, such as the Covid pandemic, can lead to sudden material shortages that impact costs. Such instances are addressed and adjustments calculated promptly upon identification – but will result in an addition to the budget.
For this reason, it is wise to add a contingency of 10% of your overall budget.
See our page on Extension Builders for more information and how to get in touch for a quotation.
