Rights under Life Estate Deed

"Does someone who has deeded their property to their heirs, but retained a life estate interest have the ability to sell mineral rights or timber off of the property? Also, can they alter or tear down existing structures on the property?

Interesting question. It would seem that the first thing to do is have a real estate lawyer review the deed that created the life estate to see what the language specifically provides. Next you need your attorney to review local (state) law governing life estates. It is likely that since a life estate gives the life-tenant only the right to use the property during life, that removing or selling mineral or timber rights, or tearing down an existing structure would be viewed as "waste" and not permissible.