It never hurts to try and resolve problems with your adversary by simply talking to them about it. Most problems can probably be solved out of court and without the need for lawyers. Just tell your landlord that you'd prefer notice before he climbs on your roof. This may solve the problem without having to resort to legal threats.
Also, the rule is 48 hours, not 24. Twenty-four hours applies if the landlord needs to show your unit to a prospective tenant. RCW 59.18.150(6).
The statutory reference is RCW 59 18 150. Your tenancy extends to the property boundaries, not just the inside of your house. But seeing if you can straighten this out informally is a very good idea. Elizabeth Powell
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As usual, the two people having answered this question are continuing to perform an excellent job in explaining the law and discussing the "human element" that surrounds everything. I do a heck of a lot of landlord representation and I can tell you that from what I am reading from you it sounds like you are a good tenant that this landlord will want to keep. I suggest that if this bothers you (and it would bother me as well) that when you approach him/her that you do it with tact and explain how you know it is good intentioned behavior but that it is disturbing to you. In addition, you may want to start a diary and record the fact that you had this conversation with your landlord in case his/her reaction and/or subsequent behavior continues to be unsatisfactory.