Before you do anything else
Define the scope clearly before speaking to any tradesperson. Write down exactly what you want — the more specific you are, the more accurate the quotes you receive. Vague briefs lead to vague quotes, and vague quotes lead to disputes about what was included.
Budget: the real number
Set your maximum budget before you get any quotes. Add a 15–20% contingency for unforeseen issues — in older properties this should be 20–25%. Home improvement projects almost always reveal surprises (rot, hidden damp, inadequate wiring). A contingency is not pessimism — it is planning.
Permissions and regulations
Check whether planning permission is required. For work requiring Building Regulations (most structural work, extensions, loft conversions, electrical and gas work), factor in the time and cost of compliance. Building Control fees for a typical extension run £500–£1,500. Not obtaining required approval can cause serious problems when you sell.
Choosing your tradesperson
Get at least three quotes. Check reviews, qualifications, and insurance. Meet the person who will actually be doing the work — not just the estimator. Verify that they have done similar work before and can provide references.