Cast Stone Window Sills: Planning for Effective Drainage Lug sills carry integral projections that embed in the masonry and anchor the stone mechanically. Slip sills rest on a mortar bed alone. For brick and brownstone restoration in the Bronx and elsewhere in the city, lug sills are the usual choice. https://www.ganjingworld.com/article/1ive3rj4qna2itqpHnaIRb0dI1tv1c