A knitted fabric comprising two confronting webs, each web being formed by a series of continuous lengths of yarn extending generally parallel to one another and having loops arranged in walewise and coursewise rows. One web overlies the other and, the two webs being united at intervals by a tuck stitch of yarn of one web engaging the other web. The tuck stitches are spaced apart walewise by a plurality of courses to create channels between the stitches. The channels extend walewise of the webs. At least one yarn is inserted under tension between the two fronting webs and held in parallel relation to the parallel lengths of yarn. When relaxed, the yarn inserted under tension causes the confronting webs to be spaced apart within each of the channels.