Previously, we examined tractable parametric shape grammars (Yue and Krishnamurti, 2013), and developed a general paradigm for implementing classes of such grammars (Yue and Krishnamurti, 2014). A tractable shape grammar has polynomial computing complexity, and is specified in a way that is readily transformable to a computer program.By contrast, traditionally, shape grammars have been typically developed without a computer implementation in mind, either requiring ambiguity to be clarified, or it is hardly possible for the grammar to be implemented by a polynomial algorithm. Each tractable shape grammar is tied to a particular framework, which is backed by a data structure and supports a meta-language. In this paper, we illustrate the development of tractable shape grammars by transforming a shape grammar developed, essentially, in traditional fashion for the Baltimore Rowhouse (Hayward 1981;Hayward and Belfoure, 2005). The development is for a specific application context, namely, to determine the interior layout of a building given its external features; and the process serves as a general strategy for developing tractable shape grammars.