Here is the issue: whether this considered a latent or patent defect. Yes, you are correct in that your landlord must provide you habitable living conditions and must repair any defects. Since this is not simply a broken oven or dishwasher but the stuff that actually makes the house a house, you might review your lease, pinpoint the exact provision relating to potential breaches by the landlord and habitability and inform the landlord in writing that his breach has caused you to move. You inform him you expect the return of your full deposit and you expect that he will help you move to a new location or provide moving expenses since he did not ensure his place was habitable prior to your move-in. Contact your state's attorney general and find out if there are complaints on this landlord and explain the issue of the Chinese drywall. If your landlord refuses to give you your money back, contact the attorney general and HUD to file complaints against him.