What kind of wood is timberline?

Timberline as wood type is not a specific species of wood, but rather a brand name and term used in several contexts for engineered wood, roofing, and construction products. In construction, Timberline is not a species like pine or oak, but is used as brand name for several wood products. GAF Timberline shingles are not wood at all, they are fiberglass asphalt shingles made to look like wood shake, but not wood. Timberline as wood product often refers to Timberline engineered wood siding, trim, or lumber that is made from composite wood, oriented strand board, or treated wood for exterior use. Some companies sell Timberline wood as pressure-treated pine or cedar used for decking and fencing that is marketed as Timberline series. In flooring, Timberline wood might refer to laminate or engineered hardwood flooring with wood-look finish in rustic style. The term timberline itself refers to tree line elevation where trees stop growing, not wood species, so timberline wood could mean wood harvested near timberline, which would be species like Engelmann spruce, subalpine fir, whitebark pine, or lodgepole pine that grow at high elevations near tree line in Rocky Mountains. At timberline, trees are stunted krummholz. So if you are buying Timberline wood product, it is likely engineered wood, composite, or treated pine marketed under Timberline brand, not specific species, but wood from timberline areas is typically high-elevation conifers like spruce and fir.