Thanks again for all of the input and advice, as well as the words of caution not to rile him up too much.
I do have plans in place for moving out. I will be graduating from college this June and plan to move back in with my parents until I can get all of my ducks in a row. The lease officially ends at the end of August, but the landlord would actually be doing me a favor if he terminated the lease early or did something which violates our lease and thus allows me to leave without penalty. It would essentially save me two months of rent, which is advantageous. So... I actually sort of want him to give me the boot -- but only as long as it is done in a way that means he has no right to keep my security deposit, and hopefully peacefully enough that he doesn't try to trash my name to future landlords.
I actually managed to get some legal advice today through a program for low income individuals which allows you to speak with a lawyer and get input. The present plan of action is to expressly inform him via certified mail that he does not
have my consent to begin construction on the garage while I am still living in the duplex. If he disregards my letter and begins construction anyway, I will likely be able to invoke constructive eviction. I have included the definition of this below, and underlined the sections which are especially applicable to me.
"Occurs when a landlord does not physically or legally evict a tenant, but takes actions that interfere with the tenant's use and enjoyment of the premises significantly
. Constructive eviction can occur as a result of the landlord's breach of the implied covenant of quiet enjoyment if (1) the landlord substantially interferes with the tenant's use and enjoyment of the premises by his actions
or failure to act to resolve a problem; (2) the tenant gives the landlord notice of the problem and the landlord fails to respond and resolve the problem; and (3) the tenant vacates the premises in a reasonable amount of time after the landlord fails to resolve the problem." Constructive eviction | LII / Legal Information Institute