As a general rule, a landlord has no duty to a tenant or to one claiming through a tenant’s title for injuries caused by a dangerous condition which existed at the time the tenant took possession, Reckert v. Roco Petroleum Cory., 411 S.W.2d 199, 204-205 (Mo.1966), unless the condition is known to the landlord and not to the tenant and not discoverable by the tenant in the exercise of ordinary care. Milne v. Pevely Dairy Co., 641 S.W.2d 158, 160 (Mo.App.1982). On the record before the trial court knowledge of defect was denied by affidavit and deposition of the owner. Further, the tenants acknowledged by deposition that they were aware of defects in the condition of the porch. They also testified that they had alerted and warned plaintiff of the defects before the casualty.