Discriminate against any handicapped person by refusing to permit, at the expense of that person, reasonable modifications of existing premises occupied or to be occupied by such person if such modifications may be necessary to afford such person the full enjoyment of the premises. In the case of a rental, the landlord may, where it is reasonable to do so, condition his or her permission of a modification on the renter agreeing to restore the interior of the premises to the condition that existed before the modification, reasonable wear and tear excepted. However, where it is necessary to ensure with reasonable certainty that funds will be available to pay for the restorations at the end of the tenancy, the landlord may negotiate as part of such a restoration agreement a provision requiring that the tenant pay into an interest bearing escrow account, over a reasonable period, a reasonable amount of money not to exceed the cost of the restorations. The interest in any such account shall accrue to the benefit of the tenant. A landlord may condition permission for a modification on the renter providing a reasonable description of the proposed modifications as well as reasonable assurances that the work will be done in a workmanlike manner and that any required building permits will be obtained.