When building the shed, you should make sure the plans are detailed and come with step by step instructions, as well as with a complete list of the materials. it is essential to invest in high quality materials, that are also water-resistant, such as pressure-treated lumber. how to build a small shed roof.. Shed roof is one of the simple roof types, it is a mono pitch roof with one way sloping surface, suitable for small houses plans or covered porches.. 6