The present disclosure describes a treated cellulosic material comprising a cellulosic material having a porous structure defining a plurality of pores, at least a portion of the pores containing a treating agent comprising a polymer, the polymer comprising a polyurethane polymer. The present disclosure further describes a method for preparing a treated cellulosic material comprising providing a cellulosic material; and a first treatment protocol comprising impregnating the cellulosic material with an aqueous dispersion comprising a polymer, the polymer comprising a polyurethane polymer; and a second treatment protocol comprising impregnating the cellulosic material with a modifying agent, the modifying agent comprising a hydrophobic amine.