If you have an active infestation of termites, powder-post beetles or wood borers deep inside the wood then Timbor would not make it through the wood to kill these insects, up to 4 inches with one application or 8 with 2 appliations. BoraCare is a liquid borate but has an additive, a glycol solution, which allows the product to penetrate through the entire piece of wood, therefore it should be used any time you have an active infestation because you are guaranteed it will kill anything in the wood no matter how deep it is. Also, BoraCare will last forever in the wood so you will never have to worry about any infestations in the wood that you treat ever again.
Timbor is more typically used on wood that will not be exposed to weathering and the outside. You would need to re-apply the Timbor each time you re-sealed the wood with the Behr product. The same company that makes Timbor makes a product called Bora-Care. It is more expensive, but it is a liquid solution instead of a powder. The Bora-Care will penetrate deeper in the wood, and protect the wood indefinitely so you would not have to re apply the product ever again. Also, Bora-Care dries clear and is easier to paint or stain over whereas the Timbor leaves a white powder on the surface and is more difficult to paint or stain.
Timbor can be applied to raw wood for the interior walls. Please refer to the product label for complete application instructions. If the wood will remain exposed as decorative structural wood, then you may want to use Boracare instead of Timbor; Timbor sometimes will dry with a visibly white texture that may not be as appealing in living spaces. It is also much easier to apply stain, paint, or sealant after applying Boracare.