It won't sag if it is hung from a full-width rod (metal drapery rod or closet pole size wood rod w/b best for that size quilt) in a full-width sleeve. Much larger quilts are hung frequently and they do not sag or distort as long as the weight is evenly distributed across the hanging mechinism...meaning don't use clips or hooks or any kind of spaced hanging system. A regular cotton backing fabric is fine.