Get it right, as Bellway did this week, and everything's rosy, but trip up, like Gleeson has this year, and the results can be messy indeed.
Bellway reported a 23% jump in pre-tax profit to £125.3m for the year to 31 July. However, a glance at Gleeson's figures would serve as a sober reminder that it doesn't take much to go from hero to zero.
Gleeson, one of a dying breed of firms combining housing and contracting, reported a 22.9% fall in profit, mainly from cost overruns in its housing division, in which operating profit dropped by more than half to £500,000. The firm has been forced to cut production, pull out of some developments and restructure.
The management is promising a speedy return to profitability but the City will take a long time to forget. If firms can't make money with house prices rising 20% a year, how will they cope when the downturn finally hits?