Since the beginning of the pandemic, North American lumber prices have been more volatile than at almost any other time in history, leading to some major headaches for homebuilders and buyers.  In fact, the volatile swings in lumber over the past year alone have pushed the average price of a new single-family home up more than $18,600, according to the National Association of Homebuilders.  Over the past three months, however, with interest rates rising and the housing market cooling, demand for lumber is falling—and so are prices.  Lumber futures are down ...