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How to Design a Porch Post

F.R.R. Mallory

Porch posts are not only decorative, they are also often functional. For a porch post to support the weight of a porch roof, and to contribute to the curb appeal of a home, several factors must be considered in the design. The size and construction materials of a roof determine the amount of load being placed on porch post support members. Typically load transfers outward (except with cantilever roof projections). For most porch applications the post is working to hold up the load of the roof. To determine load, visit your local lumber yard with the dimension and construction materials of your proposed or existing porch roof. Most lumber yards have a load calculator on their computer systems. This will tell you the minimum size of your porch post, which is where you begin your design process.

Designing Porch Posts

Inviting front porch with grand porch posts.
  1. Use your computer to browse to this Northern Arizona University website, http://jan.ucc.nau.edu/~twp/architecture/, which features 640 images of American home styles. This will allow you to correctly identify your home style, and it will give you insight into the types of posts typically used on your style of home.

  2. Note your home's architectural style and lightly sketch several posts that are similar to the type of post you would like to design for your home. Take a few minutes to study some of the images. Physical load on a post is one consideration, visual weight is another. If a post is visually too skinny it looks like the roof will crush the post. Also note if posts are typically used in groups; this trick will also spread physical load and increase visual load.

  3. Measure your porch height from the top of the porch floor to the lowest visual point of the porch roof. This is often at the bottom of the crossbeam where the porch-post will mount but occasionally a roof overhang will be lower. This will give you the visual height of your post. Most porches require the installation of railings for safety, even on older homes that may have been built with no railings. Check your local building codes to clarify this. If you add railings they will be at a specific height (by law) and these will affect your design.

  4. Using your enlargement, place tracing paper over the image and sketch in a straight post of the approximate width of your bearing post. Generally, this size of post will look too narrow. Larger posts are more expensive. Some column and post manufacturers offer composite outer columns and post designs that mount around load-bearing inner posts.

  5. Add to the width of your sketched post until it looks appropriate for the visual weight of the porch. Lightly draw railing lines if railings are required. For turned post styles the addition of railings moves the turned portion of the post above the proposed railing height. Note if the post looks squatty. Some posts are short because of the lowered height of a porch roof. This may eliminate some post styles as they will not have the right proportions to look good. A sketch will answer that question.

  6. Select your preferred post design and make your estimate of how wide the post should be to look appropriate on your porch. Adjust your design to be project specific (for custom-made turnings as an example) or use your computer to find a post of the right dimensions and price point for your project.