Ann Arbor — Ch. 105 Housing Code § 8:528

(1) Weatherization requirements. In order to help reduce the high cost and ecological harm of excess energy use, it is hereby ordained that no person shall let to another for occupancy any dwelling or dwelling units which are not equipped with weatherization in safe, good order as follows:
(a) All cracks or gaps in or between building materials which are used on exterior building surfaces or on surfaces which interface between heated and unheated spaces within the building, which allow loss of heat from the interior to exterior of the dwelling, or from heated to unheated spaces, including as well, where necessary, cracks or gaps in the interior or exterior walls, shall be sealed with weatherstripping or caulking or other insulation device or system so as to assure reasonable weatherization. Such weatherization shall include but not be limited to the following: All cracks at window frames where glass meets frame, and where frame meets wall, shall be applied with sealant material or weather resistant caulking outside the dwelling as needed. Cracks at door frames of doors providing access from unheated to heated space where any glass meets frame and where frame meets wall shall be applied with a sealant material or weather resistant caulking, both inside and outside the dwelling as needed. Cracks in windows or doors where sliding or swinging windows or doors meet their frames shall be sealed with spring steel, rubber, foam or other weatherstripping or insulation device, except where such window or door fits so tightly in its frame that such insulation is not useful to prevent heat leakage. Cracks at locations where the building structure is penetrated by utility connections, pipes, wires, dryer vents, exhaust fans or other objects, devices or systems, shall be applied with a sealant material or weather resistant caulking as needed. Accessible cracks where building foundation and structure meet, and where exterior siding material meets trim, and where exterior siding boards or pieces have separated due to warping, and at all fixed joints on the building, shall be repaired, if needed, and applied with a sealant material or weather resistant caulking.
(b) In every unheated attic or other unheated top story directly under the roof, the floor shall be fitted with insulation of such quality and grade that the insulation material alone, exclusive of the floor material, provides an R insulation value of not less than R-30.
(c) In every heated attic or other heated top story directly under the roof, the roof shall be fitted on its underside with insulation material of such quality and grade that the insulation material alone, exclusive of the roof material provides an R insulation value of not less than R-30.
(d) In the case of an unheated attic or other unheated top story, a variance may be granted in the proper circumstances for insulation under the roof rather than on or in the floor.
(e) If prior to December 1, 1985 the attic floor or roof has been insulated such that the insulation R value of the installed insulation alone, disregarding the insulating value of the structural elements is at least R-19, then the R-19 insulation shall remain sufficient and in compliance with this section.
(2) Exceptions. This section does not apply in the case of:
(a) An owner-occupant landlord;
(b) A bona-fide nonprofit cooperative;
(c) A bona-fide tenant subletting his or her residence;
(d) A homemaker on sabbatical or temporary leave or whose personal home is rented up to 2 years while it is for sale;
(e) A landlord who pays all of the utility heat bills for the dwelling and does not charge the tenant for heat or increases in utility heat bills;
(f) Where due to the unusual structural characteristics of the building or unit, the required weatherization cannot possibly be installed without extraordinary and unusual structural change, or would have no weatherization or insulating value, or is unnecessary because the respective floor or roof is so constructed as to continuously and at all places exceed without insulation the R value of the required insulation.
(g) Buildings constructed later than 1977, with the exterior envelope in compliance with Model Energy Code requirements, shall be exempt from the R-30 insulation provisions provided the exterior envelope and component materials are maintained.
(3) Effective date. The effective date for this section (8:528) shall be December 1, 1985. Required weatherization shall be kept in good order.