(1) The provisions of ss. 738.701-738.705, so far as applicable and excepting those dealing with costs of, or assessments for, improvements to property, shall govern the apportionment of expenses between tenants and remaindermen when no trust has been created, subject to any agreement of the parties or specific direction of the taxing or other statutes, but when either tenant or remainderman has incurred an expense for the benefit of his or her own estate without consent or agreement of the other, he or she shall pay such expense in full.
(2) Subject to the exceptions stated in subsection (1), the cost of, or special taxes or assessments for, an improvement representing an addition of value to property forming part of the principal shall be paid by the tenant when the improvement is not reasonably expected to outlast the estate of the tenant. In all other cases a part only shall be paid by the tenant, while the remainder shall be paid by the remainderman. The part payable by the tenant shall be ascertainable by taking that percentage of the total that is found by dividing the present value of the tenant’s estate by the present value of an estate of the same form as that of the tenant except that it is limited for a period corresponding to the reasonably expected duration of the improvement. The computation of present values of the estates shall be made on the expectancy basis set forth in the official mortality tables, and no other evidence of duration or expectancy shall be considered.