You may have big plans to undertake a house extension, but how far will your available budget stretch? Before making plans, you need to get an idea of what can be done with the money you have available.
Here we explain what types of project can be done with a budget of £30,000–50,000. This will comfortably allow you to create a substantial house extensions including loft conversions, garage or cellar conversions, large single-storey extensions and even a modest two-storey extension. We also show great examples of homes extended within this budget.
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1. Orangery-style house extensions
A traditional-style house extension option, designed to be in keeping with a period house and measuring 30m², would cost between £1,250 and £1,450 per m² depending on location. A room measuring 4x7m would be ideal for a dining or sitting room and, in many instances, would fall within permitted development rights and so not require planning permission.
2. Extend your house with a garage conversion
An attached double garage measuring 28m² could be turned into extra living space at a basic cost of £850 to £1,050 per m². To then integrate this space into the existing house by removing the partition wall – replacing it with an RSJ – add around £5,000 to the cost.
- Read more: A beginners guide to garage conversions
If the space were to become a new kitchen, the cost of new units must also be added at around £5,000 upwards, depending on the kitchen supplier chosen. Your permitted development rights mean a garage conversion will not usually require planning permission, but it must comply with building regulations as the project would constitute a ‘material change of use’.
3. Extend downwards with a cellar conversion
An existing cellar measuring around 35m² could be converted into an additional living room or home office at a cost of around £850-1,050 per m², including dampproofing (a tanking membrane) and insulation.
Adding a new lightwell and window would cost an additional £4,000-5,000. Cellar conversions come under permitted development rights but, as above, this is a ‘material change of use’. For details of specialist cellar-conversion firms, try basements.org.uk
4. Single-storey house extensions
This level of outlay could be sufficient to create a substantial house extension, 30-40m² — budget for £1,050 to £1,450 per m². This might be enough to extend by around 4m right across the back of a typical semi or detached house, with either a flat or low-pitched sloping roof — ideal for creating a large open-plan kitchen-diner.
A contemporary design with folding-sliding doors, glazed roof lanterns and large floor-to-ceiling glazing units would cost £1,800 to £2,200 per m², so on the same budget the scale of the space may need to be reduced to around 23m². Many single-storey side and rear extensions will fall within your permitted development rights, but always check. And Building Regs will apply.
5. Two-storey house extensions
More cost-effective than a single storey house extension because they double-up on the use of the foundations and roof – two of the most expensive parts of a build – a two-storey extension on this budget could measure up to 30-40m² (both floors). At the rear of a property, this would typically extend the kitchen with a new bedroom above.
Many such extensions projecting no more than 4m from the rear of the original house are covered by permitted development rights, but a two-storey side extension will require planning consent – and don’t forget Building Regs.
Those with a smaller budget might wish to see what you can do for between £20,000 and £30,000. Or if you have a little more to spend, take a look at extensions between £50,000 and £90,000