Boron in the form of boric acid is well known for its efficacy against wood destroying organisms, as well as for its high leachability from treated wood when in outside exposure. Moreover, due to the European directive 2008/58/EC, boric acid is only authorized at low levels. In order to keep considering boric acid as an interesting active ingredient for wood protection, the issue is now to fix it into the wood through networks that would leave boron enough freedom to stay active, would greatly reduce its depletion from treated wood, would remain eco-toxicologically acceptable. The associations of boric acid and tannin-hexamine (hexamethylenetetramine) resin were studied for their abilities to treat wood samples. These treatments were evaluated for their efficiency after leaching against Pycnoporus sanguineus (tropical bown rot), the exposure been done in tropical conditions. The fungal protection was maintained even after leaching, and these systems were also shown interesting for wood fireproofing.