What are the Requirements for a Valid Will in Washington?
In order for a Will to be valid, the state of Washington requires that you meet four requirements:  

You must be at least eighteen years old.   

You must be of “sound mind.”  This means that you must be able to understand what a will is, who your family members are, the extent of your property, and whom you are giving your property to.  

Signed by Testator
You must sign your will.   If you are unable to sign your own Will, someone else may sign it for you under your direction and in your presence.  

Signed by Witnesses
Your Will must also be signed by two or more witnesses.  These witnesses must sign the will in your presence.  It is a wise practice to make sure your witnesses are “disinterested,” or in other words, will not be receiving a gift under the will.  This is because having a will signed by an interested witness, arouses the suspicion that the witness procured the gift by undue influence.   

You do not need to have your will notarized in order for it to be valid.  However, Washington does allow testators to attach to the will a notarized “self-proving affidavit” which is signed by both the testator and witnesses.  This affidavit saves time in the probate process.