john's choices as the unit owner are the modification cannot be refused; the tenant can pay and should restore to original condition upon move out. As he is giving rent for that house and for his special case this can't refused. but a condition can be added like while returning the house should be provided at the original condition. This type of renovation can be done by the tenant or done by owner and charged to tenant. As it is for the tenant convenience only permission can be given by the owner and cost incurred should be beared by the tenant.