Part II – How to Build a Screen Porch – From Foundation & Deck, to Walls and Support
Nothing bothers me more than deck posts that are not centered on piers. Builders and homeowners go to great lengths to try to figure out where to dig piers. They can spend hours! Then you go to build the deck and find out that you were off by 6 inches. That is why we just built the deck outline FIRST. Now that the corners of the porch have already been established you can easily drop a plumb bob and find the center of your piers. Since you haven't placed any other floor joists, it will be easy to dig the holes with a post hole digger standing both inside and outside the box.
I prefer to dig to the frost level in my area and pour an 8 inch thick layer of concrete in the bottom of the hole. Then the next day, I insert the treated lumber post which is attached or notched to accept the joists. I fill around the post with rounded gravel to within 6 inches of grade level. The final 6 inches are filled with another layer or doughnut of concrete. By doing it this way, it is easy to replace the post should it become necessary.
Construct the deck or floor of the porch after you install the remainder of the floor joists. Use treated lumber for all of this. Do not put any spacing between your decking boards. They will shrink slightly over time creating a slight gap. Before you start nailing, you may want to consider pre-finishing the deck boards with a sealer, especially the underside and the edges that will not be exposed after you nail them down. Also, how about getting your electrical feed wires installed and possibly a gas line for your grill. You better think about how these things are going to get from the house to the porch!
The walls of the screened porch are simply screened panels that fit between posts that support the roof structure. The types of panels are up to you. To minimize posts, you will need to create large panels. The width of the panels is a function of the width of screening material that is available. Do not build your panels and then try to find screening! Plus, building the right size will minimize waste of screening. Local lumber companies will be able to hook you up with someone who makes screen panels. If you want to make your own, or use prefab panels, go for it. You can always buy extra wide and tall screen doors and just use those. By the way, you don't put these panels up until the last day!
All of the wood that is below roof level must be treated lumber or a naturally decay resistant lumber such as cedar or redwood. I have had great success using redwood for my screened porch projects. Many people do not realize that there are various grades of redwood available. The lower grades often have very acceptable tight knots. It is very economical. I would give this serious consideration. Do not use treated lumber corner posts that you wrap with redwood. Invariably the treated posts will twist as they dry out. This will cause problems. Your design and plans should call for corner and intermediate support posts that beams rest upon. The beams span over the posts and are connected with special post and beam galvanized hardware. The Simpson Strong-Tie Company makes a full line of galvanized steel framing connectors.
Part III of "How to Build a Screen Porch " awaits! The final stages of your construction project will soon have you enjoying your splendid outdoor room!