A treated cellulosic material comprising: a cellulosic material having a porous structure defining a plurality of pores, the cellulosic material comprising wood including wood or wood composite materials, at least a portion of the pores containing a treating agent comprising: a polymer comprising a water soluble polyol; and a modifying agent comprising a hydrophobic polyalkylene polyol. A method for preparing a treated cellulosic material comprising: providing a cellulosic material; a first treatment protocol comprising impregnating the cellulosic material with a polymer, the polymer comprising a water-soluble polyol; and a second treatment protocol comprising impregnating the cellulosic material with a modifying agent, the modifying agent comprising a hydrophobic polyalkylene polyol.