Understanding extension pricing
When you are thinking about adding an extension to your house, the first thing you’ll be wondering is how much it’s likely to cost. You need an idea of what sort of extension you can add to your house before you commit to having plans drawn up and applying for planning permission.
You are likely to have seen the cost estimated as a per-square-foot or per-square-metre price and be expecting builders’ quotes to reflect that. However, while an amount per square foot or square metre can give you an idea of a base price to work from, builders do not generally price house extensions this way.
So, if you’ve had a quote and can’t understand why it differs wildly from your expectations, there should be a good reason. And if your builder has quoted a price per square metre, be aware that the final price may be very different from the quote. This is particularly likely if you change the size or scope of your project: not every square metre ‘costs’ the same.
What do builders consider when they quote for home extensions?
When builders price house extensions, they will look at all the elements involved. Every building project is different, and the price should reflect all the unique elements. Adding on or taking off space will impact the price – but how it impacts the per-square-metre price will depend on what is being added or removed.
These are some of the main things that will influence the final price:
1. The type and design of an extension
A single-storey extension will require less in the way of foundations and structural work and would therefore be less expensive by area than a multi-storey extension. Simpler shapes and finishes are also likely to require less work.
Spaces that are essentially ‘empty’ from builder’s point of view, like a sitting room or dining room, should cost less per square metre than a kitchen or bathroom, for example. And installing floor-to-ceiling bifold doors across the full width of your property will not cost the same as a brick wall with a couple of windows and a door.
2. The type and quality of materials used
Not only is there a range of materials to choose from, within each material choice there is a range too. For a roof, for example, you could use tile, slate, thatch, clay, asphalt – the list goes on. Each of these materials will have a different cost for the same size roof. And for each of those individual roof types, you will find cheaper and more expensive alternatives.
For your build, there may be restrictions on what materials can and cannot be used. This could be due to structural reasons: for example, a certain type of ground might have implications for the foundations. The choice of materials could also be due to planning restrictions or even just your personal preferences.
When a builder quotes for an extension, they will either take a view and use an average price for each of these elements or they will be guided by more detailed information they have to hand or that you have given them. Remember, they may have to make extra allowances for costs to ensure compliance with buildings regulations too.
We learnt during COVID that we can’t always rely on things staying the same price throughout a project. Shortages in building materials due to restrictions during the pandemic meant the cost of basic supplies varied wildly. This had far-reaching consequences – some we’re still feeling.
3. The cost of labour
How labour intensive your project will be will depend on what you are doing. And the cost of labour will vary according to many things, including the tasks and the level of skill required. You may also need to factor in other considerations. This will include the location, for example whether you are in a city or out in the countryside, how difficult your site is to access, how long your project is going to take, and maybe things like the season of the year.
For specialist projects you also may need to include travel expenses or other additional costs in bringing equipment or workers to site. It’s also worth remembering that labour costs can vary depending on where in the UK you are located.
4. How much preparation is required for your extension
You might be building out onto solid, cleared, level ground – maybe it’s currently a patio area or level bit of garden, for example. Alternatively, you might need to clear land of vegetation, demolish or remove buildings, or level ground to get it ready – and that will cost more. If the ground needs extra work to prepare it, or foundations need to be built deeper or to a higher specification because of it, this will be reflected in the price.
Building sites also need to be safe for contractors and their staff. Depending on your project, keeping everyone safe may work out as more expensive than average. Again, if your site is difficult to access or work needs to be done to make it more accessible, this will also need to be taken into consideration.
5. How much refurbishment is being done at the same time
It’s not just about the new space that’s being added. The price for an extension should include how much interior design work needs to be done in and on the existing and new space too. Adding a room like a living room will cost less than adding a room and relocating a kitchen or bathroom to it – and don‘t forget you’ll need to refurbish the area the original kitchen or bathroom was in too.
6. Contingency costs
It’s common for unexpected issues to crop up during building projects that can lead to greater-than-anticipated expense or even change the scope. Builders tend to add an amount, usually around 20%, to cover this. If it’s not needed it won’t be used, but it ensures their clients know they will have some room to manoeuvre should the unexpected happen. Without it, people building home extensions run the risk of running out of money and their project grinding to a halt before it’s completed.
The price of materials and labour can fluctuate, things might take longer than anticipated, the condition of the ground might not be as expected and require extra measures, and so on.
7. Contract and payment terms – and VAT
The terms of a builder’s quote might have an impact on the cost. Whether or not it’s a fixed price, the structure of payments, and the time scale a builder is allowing for can all make a difference. Not all elements of a building project will be subject to VAT, so the proportion that does will also impact the final quoted price.
The more information you can give a builder before they prepare a quote – and the more attention they pay to the details – the greater the chances are the final price will resemble the quoted price, allowing for changes in scope. When you are comparing quotes and looking at them against your expectations of price per square metre, remember to take all these things into consideration.
At White Lime Interiors we have extensive experience working with builders on home extensions and are always available to help you make sense of any quotes. Why not get in touch to see how we can help with your home extension project?
