We use slow grown spruce for the walls of all our Garden Buildings as it is better all round than pine! Spruce is less porous than Pine and so less likely to shrink, warp or split. We only select slowly grown timber from colder climates which also helps keep the timber more stable as the rings are densely packed. It is also a less resinous timber than Pine, which makes the possibility of sap ruining your clothes or furnishings much less likely.