Portland cement is a central material in construction and infrastructure with the U.S. alone producing over 80 tons of it yearly. Recent developments in earthen architectural biomaterial systems offer alternatives that reduce emissions and decrease lifecycle energy. However, despite their ecologically benign nature, many earthen biocomposites underperform in strength and durability. In TERRENE a sand-based composite is stabilized with a shellfish-derived polysaccharide binder and reinforced with flax. The blend leverages solar-interactive surface inks and natural cross-linking agents and systematically evaluates their impact through droplet penetration, water absorption, contact angle, compressive strength, and accelerated weathering tests. These modifications extend water penetration resistance eightfold and yield higher strength. The system is now ready to be implemented outdoors into large span thin earthen shells with robust weathering capacity and still maintaining bio-integrated decay at end-of-life.