f most firs is considered unsuitable for general timber use, and is often used as pulp or for the manufacture of plywood and rough timber. Because this genus has no insect or decay resistance qualities after logging, it is generally recommended for construction purposes as indoor use only (e.g. indoor drywall on framing). This wood left outside cannot be expected to last more than 12 to 18 months, depending on the type of climate it is exposed to. It is commonly referred to by several different names, including North American timber, SPF (spruce, pine, fir) and whitewood.