North American lumber futures fell as much as 8.4% to $870 per 1,000 board feet in Chicago on Monday, hovering near four-month lows and extending a slump to 30% since early March.  Soaring inflation is curbing the appeal of do-it-yourself renovators to take on costly new home improvement projects. The DIY sector is the largest lumber market segment, accounting for ~40% of consumption. Inventory is piling up because of transportation snarls that have left many of North America's top producers with stockpiles at sawmills, and with a lack of railcars and ...