A shed style is the least expensive renovation because it is less complicated and less labor intensive which means that it will be lower in cost. This type can be as large as the entire length of the house, or partial depending on additional living space needed and budget. But a smaller shed dormer can have false economics. The larger the renovation is normally less per square foot than larger. A gable rear dormer looks much better than a shed style but economically costs much more because of the complexity. Also unless the builder raises the gable walls a gable dormer actual usable space is less because of the taper of the roof. The attic renovation offering the most living space would be to remove the entire roof and add a second floor that encompasses the entire footprint of the residence. This type doubles that living space by adding a full 2nd level. The styles are unlimited and relative to budget.