Your vinyl porch railings will withstand weather better if they are supported at the bottom by post trim skirts. Make yours out of hardwood and paint them with waterproof paint, as used for swimming pool interiors. Follow the steps below to make post trim skirts for your deck railing.
Step 1 - Determine Quantity of Materials Required
Each full-height vinyl support post will need a post trim skirt. Count the number of support posts and work out how many 4x4-inch squares and 2x2-inch squares you will need to cut. Be sure to purchase sufficient lumber planks to complete the task. One gallon of waterproof paint will be ample to paint all the post trim skirts for an average-sized deck.
Step 2 - Cut the Post Trim Skirt Pieces
With the table saw, measure and cut the hardwood lumber planks into the number of 4-inch and 2-inch squares you need for all the post trim skirts. Cut a few extra pieces in case there are warps or large knots in the planks.
Step 3 - Assemble the Post Trim Skirts
Measure and draw a 2-inch centered square on top of each 4-inch square you have cut, to ensure correct placement of the skirt tops. Place the 2-inch wood square on top of the 4-inch square and nail it into place in three locations: through the middle of the 2-inch square, and on two corners opposed diagonally. This will prevent the top square from shifting or spinning when you push the hollow post rail down onto it.
Be sure to drive the nails vertically through the top square into the bottom piece of each post trim skirt, to prevent the nails from poking through the vinyl support post rails.
Step 4 - Install the Railings
Apply a thin layer of all-purpose glue to the edges of the top section of the first post trim skirt. Align the first vinyl support post rail on the edge of your deck, and slip the post trim skirt under it. Check that the post trim skirt is firmly attached to the support post rail. When the rail and skirt are correctly aligned, nail the post trim skirt to the deck surface.
Continue to install the railing frames, placing the post trim skirts under each support post rail around the perimeter of the deck, and securing them to the deck. At frequent intervals, check the vertical and horizontal alignment of the support post rails and rail bars. Slip the balusters into the rail bars to complete the deck railing.
Step 5 - Paint the Post Trim Skirts
After the deck railing is fully assembled, paint the post trim skirts with waterproof paint. Tape around the bottom of each skirt to avoid getting the paint on your deck surface. Remove the painter's tape carefully from the post trim skirts after 24 hours to confirm that the paint has fully dried.