Homebuilder sentiment is at an all-time high, as city-dwellers seek out suburban homes during the coronavirus pandemic. But experts warn that an overcorrection in the lumber market could spell trouble for homebuilders and homebuyers alike.  U.S. lumber prices rose 170% from April to an all-time high in August and moderated only slightly in September, driving the cost of the average new home up $16,148 since April 17, according to the National Association of Home Builders, a Washington, D.C.-based trade organization.  “The dark cloud on the horizon of the single ...