422. Charges for permanent improvements.

In general, the tenant should be liable to bear all expenses which are of a regularly recurring nature and which relate to the occupation of the premises; the landlord should be liable for expenses which are incurred for the permanent improvement of the premises, except that in tenancies exceeding three years a share depending on the length of the tenancy should be borne by the tenant; and the covenant will not be construed so as to throw expenses of permanent improvements on the tenant unless there are words clearly requiring such a result. In each case, however, the construction