Fire sprinklers shall be required as follows:

Chapter 3, Section R313, of the International Residential Code as adopted by this chapter is amended to read as follows:

R313.1 Townhouse automatic fire sprinkler systems. An automatic residential fire sprinkler system shall be installed in townhouses.

R313.1.1 Design and installation. Automatic residential fire sprinkler systems for townhouses shall be designed and installed in accordance with Appendix V.

R313.2 One- and two-family dwellings automatic fire systems. An automatic residential fire sprinkler system shall be installed in one-family dwellings over 2,500 square feet, including the area of attached garages, and in two-family dwellings of any size.

R313.2.1 Design and installation. Automatic residential fire sprinkler systems shall be designed and installed in accordance with Appendix V.

R313.3 Alterations, repairs and additions. Where alterations, repairs or additions requiring a permit occur in existing dwellings, an automatic residential fire sprinkler system shall be installed in accordance with Appendix V under the following conditions:

1. When an addition is made and the size of the addition exceeds 1,000 square feet;

2. When an addition is made and the size of the addition plus the existing building exceeds 2,500 square feet;

3. When the value of a structural alteration or repair of an existing building exceeds 25% of the assessed valuation of the existing building or exceeds 25% of the recognized replacement cost of the structure, without consideration of depreciation, as determined under the Marshall Valuation Service Cost Handbook.

In cases falling under 1, 2 or 3 above, sprinklers shall be installed on the entire floor to which an addition, alteration or repair is made, and to each floor or basement below the addition, alteration or repair.