Washington, DC’s Construction Code of 2008 includes cool roof provisions for low-sloped residential roofs.
Roof coverings for roof slopes less than or equal to two units vertical in 12 units horizontal (17-percent slope or less) for buildings and covered parking shall conform to the this section. A minimum of 75% of the entire roof surface not used for roof penetrations, renewable energy power systems (e.g. photovoltaics or solar thermal collectors), harvesting systems for rainwater to be used on-site, or green roofing systems shall be covered with products that comply with one or more of the following:
(a) have a minimum initial SRI of 78.
(b) comply with the criteria for the USEPA’s Energy Star Program Requirements for Roof Products – Eligibility Criteria.
Source: Washington DC
Publication Date: January 2008