How to Design & Build a Porch Roof

Updated February 21, 2017

Constructing a porch roof to blend well with a home requires careful thought. Any porch design can easily devalue the look of a home. Since roof lines determine a lot about the architectural style of a house, the roof of a porch should match the house's roof lines. Drive through neighbourhoods and review home design books to gather ideas. Select a roof design that will look appropriate for many years to come. In addition, build a roof sturdy enough to accommodate a room built beneath it, in case the porch ever becomes enclosed.

Measure space allowable for the porch area. Sketch the existing house in detail on graph paper. Draw several options to see which porch design fits the house best. Review home design books to gather additional ideas. Use coloured pencils to draw the final house and porch. Include railings, steps and porch posts in the drawings.

Obtain a building permit and list of local building codes. Plan to construct a porch of concrete at least 18 inches in depth if a concrete slab will be used. Use concrete support under a wooden porch as well. Consult with an architect if there is any doubt about the foundational strength of the porch base. Make a list of all materials for construction of the porch roof and devise a budget by consulting carpenters or experts at home improvement stores.

Build support posts or columns for the porch roof from no smaller than 8-by-8-inch lumber. Buy finished post material, since the posts will be highly visible. Construct all framework for the roof and side areas of a porch using 2-by-8-inch pressure-treated lumber. Bolt all framing to the house framing versus using screws, since a porch roof is extremely heavy. Install rafters 18 inches apart and cover with 1/2-inch plywood sheets.

Install metal flashing along the seam where the porch roof meets the house wall. Cover the porch with metal sheets or asphalt shingles. Use plywood sheets under the porch as well for a finished look. Caulk and paint all exposed wood areas of the roof, so that guttering can be installed to match the home's guttering system.

Add railing and trim to the porch sitting area, so that downspouts can be secured in place. Install electrical light fixtures that match the home's design. Include porch electric fans, if this is appropriate for the architecture.


Use large sheets of plastic to protect a bare concrete floor during painting or staining. There is no easy way to remove these products from concrete. Don't install tile or carpet on the porch flooring until all aspects of construction have been completed.


Pitch any porch roof at least 30 degrees. Avoid building a flat roof, since a flat roof typically will leak over time. Construct the roof in every respect to look as if it's always been in place, not added on.

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About the Author

Judi Light Hopson is a national columnist for McClatchy Newspapers. She is founder of Hopson Global Education and Training and co-author of the college textbook, Burnout to Balance: EMS Stress. She holds a degree in psychology from East Tennessee State University, and has been a professional writer for 25 years.