Covid is causing three problems for construction companies. The first is the cash-straining shutdown itself. The second is a giant negotiation over social distancing on crowded sites. The third is the prospect of much less investment in the coming years. As I’ve written before, profit margins are tight in the construction industry. The eight biggest Irish general contractors made an average net margin of 1.8 per cent in 2018. Specialist subcontractors like mechanical engineers made 4.4 per cent. There’s not a lot of fat to cut.  Narrow margins mean every job is precariously balanced, and could easily turn into a money-loser.…