Short answers, pulled from the story.
In the United States and Canada, lumber refers to milled boards while timber describes standing or felled trees that have not yet been processed. In Britain and many Commonwealth nations, the word timber is used for both meanings, and the word lumber is rarely applied to wood at all.
Historically, the 2x4 name referred to the green, rough-sawn size before drying and planing reduced the dimensions. Standards were reduced in 1928, again in 1956, and finalized in 1961 by the Committee on Grade Simplification and Standardization. A 1964 Popular Mechanics test found that today's standard size has only 73.6 percent of the compressive strength of a true full-size 2x4.
Cornelis Corneliszoon, a Dutch windmill owner from Uitgeest, invented the first wind-powered sawmill in 1593. His machine converted logs into planks thirty times faster than the manually operated sawmills that preceded it.
Manufacturing a tonne of concrete emits half a tonne of CO2, and manufacturing a tonne of steel emits two tonnes of CO2. One cubic metre of lumber, by contrast, sequesters roughly one tonne of CO2. Cement and concrete production is responsible for around 8 percent of global greenhouse gas emissions, while iron and steel accounts for another 5 percent.
Wood kept below 25 percent moisture content on a dry-weight basis can remain free of decay for centuries. Building experts recommend 19 percent as the maximum safe moisture content for untreated wood in service, providing a safety margin below the 22-24 percent threshold at which established decay fungi can continue to spread.
Under the Method of Construction issued by the Song dynasty government in the early 12th century, timbers were standardized into eight classes, all maintaining a fixed width-to-height ratio of 1:1.5, measured in Song dynasty inches of 31.2 millimetres each. The width of any standard timber was defined as one "timber" unit, and all other structural dimensions in a building were expressed as multiples of that unit.