Wood from impregnated pine for underconstruction is available in A / B / C quality.
In case of decking wood made of pressure-impregnated pine, whitish spots occur on the surface, especially in the area of knots. It is resin that pops out during pressure impregnation which mixed with the impregnating substance. These whitish salt spots will weather over time. The wooden underconstruction made of timber joists must be well measured, so that it can withstand deformation and does not lift when swelling and shrinking during the year.