Groundworks on our 3 storey 60sqm extension started last week. We assumed we’d have no problem with planning permission, but our first plans were rejected. Second were accepted though, without too much loss of internal space.
I had a fair bit of cash to finance it, and remortgaged to cover the rest.
With interest rates being so low at the mo, I’d remortgage and overpay as much as you can each month to pay it off in a reasonable amount of time.
We are making 8 staged payments (16 week projected completion time) in arrears, so in the meantime the cash is sat gaining (a pitiful amount of) interest.