A support surface, such as an underpad, for preventing pressure sores in a patient is a multi-layer textile assembly having a skin contact layer formed from a fabric of synthetic filament yarns woven to provide air permeability and moisture vapor permeability and having a thickness of less than 1 mm. An absorbent middle layer is formed from a breathable microfiber fabric woven to provide for moisture transition from an upper surface of the middle layer to a bottom surface of the middle layer. The skin contact layer and the middle layer are stitched together using a stitching pattern optimized to produce an open pattern with minimal puckering. A bottom layer is formed from a breathable, waterproof fabric woven from synthetic yarn to produce a moisture vapor transfer rate within the range of 5,000 to 20,000 grams per meter squared per 24 hours. The three layers are attached together around their outer edges.