You are both right. L is allowed to make cosmetic repairs in anticipation of putting the house on the market. However, the house & the land it sits on are yours & you have a right to notice before they enter the land. Check your lease to see if it specifies 24 hour notice. You should also check your state's residential landlord tenant act to see if the state requires you receive 12, 24, or 48 hours notice before L enters. Once you know how much notice is required, send L a letter (certified, return receipt) telling L to give you x hours notice before entering, & warning L that you'll sue him for abuse of access if he doesn't give proper notice. Once you receive notice, you can deny L permission to enter at that time. However, you can't withhold permission unreasonably. For example, you can't require L to pay an electrician overtime rates just so you can be home from work before the electrician starts.
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This is not legal advice and you are not my client. Double check everything with your own attorney and your state's laws.