The hardwoods that we use are generally more stable and weather resistant than joinery quality softwoods. All of our softwood windows are manufactured with hardwood cills as it is this component of a window that is subjected to most of the effects of weathering. We would prefer to manufacture exterior doors in hardwood as the door stiles will be more stable and less inclined to warping and movement once fitted. All of our bi-folding door sets are manufactured in hardwood.