A fabric joining method and system for attaching a first piece of fabric having synthetic content to a second piece of fabric having synthetic content. The method includes welding the first piece of fabric to the second piece of fabric at a seam and sewing the first piece of fabric to the second piece of fabric using a stitch that crosses the welded seam. An example method includes ultrasonically welding a first piece of fleece fabric to a second piece of fleece fabric followed by stitching along and across the welded seam completely through the fabric layers using a zig-zag stitch. The system includes a first piece of fabric, a second piece of fabric fused to the first piece of fabric at a welded seam, and a thread stitched across the welded seam.