The use of pyrolysis-based wood conservation is a good alternative for the use of fossil-based creosotes. In this life cycle assessment (LCA) the environmental impact of a biorefinery approach of pyrolysis oil from forestry residues or maize digestate and its application as wood modification treatment is determined. The damage to ecosystems, damage to human health and the increased resource scarcity is studied using an attributional LCA and a sensitivity and uncertainty analysis. Based on data from an existing pyrolysis plant, it is shown that pyrolysis oil from maize digestate has a significantly higher environmental impact than pyrolysis oil from forestry residues. This is due to a lower energetic yield and a higher ash content in the feedstock. The biorefinery approach of using pyrolytic sugars as wood modification treatment shows significantly lower environmental impacts than the fossil-based creosotes, regardless of the selected end of life scenario, due to a lower toxicity and by a reduction of 82% of greenhouse gases. This shows that in addition to energy production, pyrolysis oil can be applied as biobased chemicals and materials, developing a sustainable platform based on pyrolysis oil.