How to Attach Posts to Cement Porches

Porch posts provide support to the roof's overhang. A number of methods are used to install wooden posts to cement porch decks. One method is to attach the posts to the porch deck using an aluminum plinth. The aluminum plinth is a bracket that attaches to the wooden post and dowels installed on the porch deck prevent the plinth and post from moving or shifting laterally out of place, causing loss of support to the porch roof.

  1. Drop a plumb line from the center of the soffit or overhead beam in the desired location of the post. Use the pencil and mark where the plumb bob meets the porch. This mark is the center of the post.

  2. Measure the opening between the soffit and porch deck to determine the length of the post. Use the pencil to transfer this measurement to the post. Cut the post to size using a circular saw.

  3. Place the aluminum plinth on one end of the post. Use a pencil to mark the plinth's mounting holes on the bottom of the post. Use a drill to pre-drill the mounting holes with an appropriate-sized drill bit to prevent splitting during installation of the plinth. Screw the aluminum plinth to the bottom of the porch post using a screw gun and non-corrosive wood screws.

  4. Set the post in place so that it centers on the mark made previously on the porch deck. Use a level to plumb the post. Draw an outline around the plinth and remove the post.

  5. Install non-corrosive dowels in the porch deck. Measure the bottom of the plinth to determine the location of dowel spaces and transfer the measurement to plinth outline on the porch deck. It is imperative that at least two dowels are installed on the porch deck located at opposite corners of the plinth outline to prevent the post from shifting laterally.

  6. Using a drill and an appropriate-sized masonry bit, drill the two mounting holes for the dowels in the porch deck. Sink the dowels deep enough so that they do not protrude higher than the bottom of the plinth cavity, which would prevent the post from setting flush on the porch deck.

  7. Set the post in place starting with the bottom and making sure the plinth fits snuggly on top of the dowels. Tap the top into place with a hammer and check the post for level. It might be necessary to use a brace to raise the porch soffit slightly to allow the top of the post to slide in.

  8. Attach the top of the post by pre-drilling holes on an angle through the post and toe nailing it to the soffit or support beam.