CONCORD, New Hampshire  — A bill moving forward at the State House aims to address a decades-old discrepancy in how wood strength is rated. New Hampshire lawmakers approved Senate Bill 529, which gives preference to US-harvest lumber. The bill requires state-funded building projects to include design specifications for US-sourced spruce-pine-fir. …In the early 1990s, the U.S. and Canada developed separate systems to rate the strength of framing lumber. Canadian lumber is labeled SPF, while American lumber is labeled SPFs. SPFs ended up with a lower design strength value, even though the wood used on both sides of the border is nearly identical. …Over time, the difference in design specifications has given Canadian lumber a competitive advantage, putting Hampshire lumber at a disadvantage. While lawmakers can’t change international industry standards, they can influence how the state purchases lumber for its own construction projects.