Sadly the days of a basement adding value to your property are long gone
The cost of the building is far greater than the value add.
We looked last year and the cost of the full footprint extension was around £600k, which would add just £400k to the value
A half footprint was around £350k and would add around £200k
So the main advantage of doing the half footprint is that you don’t lose as much money..!
It is also worth thinking about if or when you are likely to move. The feedback we got from estate agents is there is less buyer demand for very extended terraces
So a standard BTC house with a full basement is going to have an asking price of £2.2-2.5m, but there aren’t as many buyers for those houses as there are for under £2m, so it will take longer to sell when you come to putting the house on - months rather than weeks for a smaller house