I recently did a remodeling project that involved replacing a three-season sunroom with fully conditioned living space. Since the budget was tight, we kept the original sunroom's footprint and built on the existing brick pony wall, which was uninsulated.
The owner had lived in the house for 30 years and assured us that the sunroom had been built on a proper foundation. In our part of southeastern Pennsylvania, the code requires a minimum footing depth of 36 inches. Prudence and the building inspector required that we dig down to the footing and confirm it was where it was supposed to be.
to read the full article.