What should I check before signing a subcontract?

Read for five things before anything else. First, the payment machinery: the Due Date, the Final Date For Payment and the notice deadlines, checked against the Construction Act minimums, because amended payment terms are where cash flow problems are built. Second, time bars: clauses making notice within so many days a condition of being paid for changes and delays, the single most expensive kind of term to discover late. Third, the contract documents themselves: the order, the numbered documents, the schedule of amendments and whatever the enquiry letters say is incorporated, because the deal is the whole stack, not the order form on top. Fourth, responsibility you may not mean to take: design liability dressed as coordination, or a fitness for purpose obligation, the duty that the finished work will do a job rather than that you took reasonable care doing it. Fifth, the deductions machinery: contra charge rights, retention percentages and release triggers, and how liquidated damages flow down. None of this takes a law degree; it takes an hour with a highlighter before the signature instead of after the first dispute.

Say a roofing subcontractor gets a 30 page order for a £180,000 package the day before starting on site, with a covering email saying work must begin immediately. An hour's read finds a 7 day time bar on variation notices, payment terms stretching the final date to 45 days, and a schedule of amendments passing the main contract's liquidated damages down in full. None of those terms is illegal, and all of them are negotiable the day before signature; none of them is negotiable a year later at final account. The roofer sends back three short amendments, gets two accepted, and prices the third into its risk. The lesson is that the cheapest contract review you will ever get is the one that happens before you sign.