I just signed a 1 year lease on a nice but older 3 bedroom home. This clause does not take effect until month 6 of the lease. Just wondering if this is a common practice. This is in Texas

It depends. Is this a private owner? If so yes its legal. Its to protect themselves. Thats why it doesnt take effect unitl the 6th month. In 6 months regular issues would be resolved. After six months normally issues are caused by the tenant. Honestly $100 is not a large amount to ask. Do you pay a security deposit as well?