How to Build Porch Beams


A covered porch can provide endless opportunities to enjoy the outdoors while under the protection of a roof. A wooden porch cover can be installed with beams, or rafters, constituting a frame built to support the weight of the structure. These covers can be custom built to suit the size you require. When designing your cover, take into account variables like the slope, if any, and the weight the cover will support, like roofing materials, heavy snow or even a top deck.

Things You'll Need

  • Measuring tape
  • Saw
  • 2 by 6 treated lumber
  • Posts
  • Post anchors
  • Deck screws
  • Nail gun
  • Construction glue
  • Determine the place for the rafter plate to be attached to the side of your house. Take into account if the roof will be sloped or if will be flat to accommodate an upper deck. Remove any siding from this area as necessary to accommodate the 2 by 6 plate so that it can be firmly attached to the house.

  • Install the 2 by 6 rafter plate to the side of the house with the lag screws. Drill any pilot holes necessary to securely anchor the rafter plate against the wall where you have removed the siding. The rafter plate must be attached to the house securely to help support the weight of the rafters or beams when they are installed.

  • Set the post column anchors over the top of the outermost deck floor joist and attach them to the deck, with screws screwed through the deck flooring and set into the joist. Set the post anchors into a concrete patio with concrete screws anchoring them in place. Place an anchor along this joist every 6 to 10 feet and on each corner. Locate them about 3 to 10 inches from the edge.

  • Set the posts into place in the anchors. Use a post level to make sure they run perfectly straight up into the air. Use the level on each side and verify the posts are plumb before attaching them to the anchors with deck screws on the bottom. Brace the posts to keep them level if needed using spare lumber set into the ground and leaning against the post.

  • Attach the header to the tops of the posts set in step 3. Lay the header with side up across the tops of these posts and toenail them into place with the nail gun shooting in the nails at angle to hit both the header and the posts. Attach a second header to the first one on top of the posts to provide double strength. These two pieces of the header can be glued and screwed together with deck screws. A header will support a great amount of the porch covers weight and metal hangars can also be attached for additional support if necessary.

  • Start from one end and place the rafters between the rafter plate and the header, toenailing them into place as you go on each end. Attach on one side of the cover and then do the other side to keep the cover frame steady and firmly lock it into place. Metal hangars can be installed on each end to secure them to the header and the rafter plate as you go. Work in from each side, and finish with the middle rafter. These rafters should be placed between 16 to 30 inches apart, depending on the load your roof will carry. In areas with high amounts of snowfall, 16 inch rafters will help support the weight better than those that are placed farther apart.

  • Measure and cut bracing from the spare 2 by 6s to fit between the rafters. Place the bracing between the rafters at appropriate intervals and secure the braces into place with nails driven through the outside of the rafter and into the ends of the braces. Attach the braces so they are staggered between the rafters for easy attachment and at enough places to brace the whole frame tightly together. The porch cover frame is now properly supported for you to lay whatever roofing material you have chosen.

Tips & Warnings

  • Carefully planning and measuring your porch cover and taking these measurements to the building supplier so they can pre-cut the boards will make the job go faster.
  • Make sure the porch cover frame is securely anchored together or the structure could fall and cause injury.

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  • Photo Credit front porch image by Steve Lovegrove from
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