Steel Door Institute
The Steel Door Institute (SDI) was established in 1954 as a voluntary, unincorporated, non-profit business association whose mission is to promote the use of steel doors and frames in the construction industry.
Membership is open to all American based companies engaged in the production for sale of swing steel doors and/or frames on a national basis for at least two years. Members mutually agree to establish and abide by SDI manufacturing and quality standards that apply to all doors and frames they produce.
Representatives of SDI member companies create and publish manufacturing, quality and performance standards promulgated by the association and distribute them to licensed architects and construction specifiers at no charge