"The normal expense of supporting a house will be £6,000-£21,000, however, this will shift contingent upon the Underpinning strategy, size of the property, and its present status.
Underpinning a single wall in a 2-bed terrace (4m) 3 weeks £6,000 £10,400 £4,800 Underpinning a single wall in a 3-bed semi (5m x 4m) 4 weeks £13,500 £23,400 £10,800 Underpinning a single wall in a 4 bed
detached house (8m x 6m) 6 weeks £21,000 £36,400 £16,800"
https://discusswisely.com/t/how-much-does-it-cost-to-underpin-a-house/234