North American lumber companies plan to ramp up production by expanding existing mills as strong home construction fuels the need for more wood.  West Fraser Timber Co., the world’s biggest lumber producer, plans to expand capacity at five of its lumber mills in the U.S. South. Interfor Corp. is rebuilding a sawmill in Georgia that is on track for completion by the end of 2021. Both companies expect home-building and renovation demand to continue supporting strong prices for wood products in the near future.  Interfor shares soared to a new high Friday after ...