Housing Starts and Building Permits * Raw Data Available At: http://www.census.gov/ftp/pub/indicator/www/housing.html. Housing Starts are a measure of the number of residential units on which construction is begun each month. A start in construction is defined as the beginning of excavation of the foundation for the building and is comprised primarily of residential housing. Building permits are permits taken out in order to allow excavation. An increase in building permits and starts usually occurs a few months after a reduction in mortgage rates. Permits lead starts, but permits are not required in all regions of the country, and the level of permits therefore tends to be less than the level of starts over time. The monthly national report is broken down by region: Northeast, Midwest, South, and West. Briefing recommends analyzing the regional data because they are subject to a high degree of volatility. The high volatility can be attributed to weather changes and/or natural disasters. For example, an unexpectedly high level of rain in South could delay housing starts for the region.