I used Timbor on the inside of my wall cavities and sills when I gutted my 100yr old house. It claims to deter insects and mold. I paid $75 for a 5 gal bucket of powder (to be mixed with water and sprayed on) 4 years ago. The house never had insulation in the walls and I didn't replace the original cedar siding. If any moisture got into in the past, it would have dried pretty quickly. I figured the Timbor would help if a little bit of moisture got into the wall after it was full of insulation. It can't be used on exposed wood work though.
