Budgeting for Your Extension: What It Really Costs

Running out of money mid-build is the most common disaster in self-managed extensions. Not structural failure. Not planning refusal. Not a rogue builder. Just the slow, grinding realisation that the numbers don't add up, and you're only halfway through.

It happens because builders quote for building work. Not for the architect. Not for the planning fees. Not for steelwork, glazing, electrics, plumbing, screed, tiling, garden reinstatement, or the dozen other cost lines that appear between day one and completion. The builder's price is one line item in a much larger budget, and if you treat it as "the cost," you will run short.