The North America Free Trade Agreement is intact, for now, following threats by President Donald Trump to withdraw from it. But the back-and-forth between the US and its neighbors is already shaking up a key component of the housing market, with more disruptions possible. …Concerns that the US would withdraw from the North American Free Trade Agreement have contributed to a jump in lumber prices since early this year. …”Given that lumber accounts for a relatively small share of overall construction costs, on its own that development will have a minimal impact on homebuilding activity,” said Matthew Pointon, a property economist at Capital Economics, in a note on Tuesday. “But, combined with labor and land shortages, it will only add to the pressure on builders to protect margins by focussing on the higher end of the housing market.”