Apologies for the delayed reply. I don’t believe eTool is able to specify the difference between sustainably managed forests vs old-growth/un-managed. The LCI data for materials is based on industry averages which will contain a mix. In saying that, we absolutely do NOT condone the harvesting of timber from old-growth forests.
The best option for you would be to find an EPD for your timber and model that in your design. Please refer to this support post on how to create an EPD in eToolLCD: https://support.etoollcd.com/index.php/knowledgebase/using-epd-in-etoollcd/