When building a roof over outside stairs, there are several areas of construction that must be addressed, such as structural concerns for the roof: will you need 4 by 4 posts, 6 by 6 posts or will you need any posts at all? Also, you will need to decide on types of materials, size of the roof, shape of the roof and aesthetics, as well. If you are planning on building a roof over outside stairs, then you should know about the materials and techniques available for a successful project completion.
Purchase large corner posts for a roof that will be freestanding and not attached to any other structure. The posts should be 4 by 4 or 6 by 6 posts that are treated cypress or cedar. Use treated, cedar or cypress framing and trim materials, as well. The hardware should be stainless or galvanized nails or screws that are at least three inches long. Use cement for securing the roof posts into the ground.
If you are attaching the roof to an existing structure, such as a porch or house, then you will need flashing to waterproof the joints between the stair roof and the existing structure.
Use metal or asphalt roofing for a more conventional roof and cedar shingles for a more custom look.
Setting the Posts
Set the corner posts for the roof 24 inches into the ground. Coat the posts 24 inches from the bottom, using tar. The tar will prevent the cement from eroding the wood. Set the posts--10 feet in height--pour wet cement around the posts and level the posts using a four-foot carpenter's level. After the posts have set up, cut the tops of the posts so that they are level. Setting the posts on uneven ground will cause the posts to stand at various heights. One note of caution before the cement dries around the post, though: Make sure that the posts are completely plumb on all four sides.
Roof Framing and Waterproofing
Attach the side beams to the tops of the posts using three-inch wood screws. Notch the tops of the posts so that the beams will recess into the posts and rest on a ledge. Construct the roof, whether flat or gabled, using 2 by 4 framing. Add 1/2-inch sheathing to the top of the roof using eight-penny nails. When attaching shingles, use 1 1/4-inch roofing nails; when attaching metal, use 1 1/4-inch screws. Add cross bracing to strengthen the structure.