R302.1

Section R302.1 is catchlined 'Exterior walls' and requires that the construction of exterior walls of dwellings and accessory buildings, as well as projections (such as roof eaves), openings (such as windows and doors), and penetrations (such as pipes or ducts) comply with Table R302.1(1), where the dwelling is not protected with an automatic sprinkler system; or Table R302.1(2) where it is. Both tables list fire separation distances and corresponding construction requirements.

This model shows an x-ray of the skin of two detached single-family dwellings on separate lots. The distance of the walls to the interior lot line are cross-referenced to the table, and the corresponding construction method must be used. The translucent projection between the dwellings, represents an imaginary vertical extension of an interior lot line. The yellow and black symbol represents a generic distance measurement. The fire separation distance for all exterior walls must be checked (not shown for clarity).