How Many Posts To Support A Roof

Measure the distance between the bottom of the porch roof and the top of the ledger beams of the porch.

How many posts to support a roof.

Load bearing posts must have a solid footing on undisturbed soil and all parts of the post must be fastened together. In all probability for this size deck you need to be talking 3 rows of support beams with 3 4 posts each one beam near house one near outside edge one down the middle to be able to get to economical and realistic joist spacing 16 or 24 and realistic post size 4x4 or 6x6 and beams 4x12 or smaller. For deck roof posts dig holes for the roof posts and pour cement to keep them secure. Our main support posts are 8 on center with a 2 x 10 on the inside and outside of the post at the top and a double 2 x6 top plate.

While many like to use the smaller 4 x 4 posts they can tend to warp after they have been standing under the weight for several seasons. We just completed a beer garden addition with a single sloped roof. Solid lumber such as 4 by 4s 6 by 6s and 8 by 8s. Most builders use 4 by 4 inch lumber.

The span on your porch posts is determined by the weight load of the roof. Using the 2005 nds i calculated that the same post can support 231 square feet so it would seem there s no problem using 4x4s to support say an average sized intermediate stair landing. Step 2 post height. The second factor will be the depth these posts are planted in the ground.

Here we look at the most common. It was 16 wide x 40 long. Large 8 x 8 posts are necessary for the use of supporting a porch roof. Porch decks also require larger footings than deck footings.

Posts and footings support the weight of your house so you have to size them right. According to the old af pa table a 4 foot douglas fir 4x4 post can support 256 square feet of deck. Sometimes they e built up from more than one size of lumber. If the deck doubles as a porch it needs to be able to support no more than 80 psf.

For post material choose one such as pressure treated pine that will resist rotting and insect damage when it is planted in the ground. Consult with a structural engineer local building officials and contractors who specialize in this work. Posts and columns may be made from several types of materials. In other words the maximum distance it can cover without support from posts.

The length of your posts will help determine the height of your carport roof. The international residential code requires railings on any deck that is more than 30 inches off the ground. However if the spacing is too wide the patio cover s beams will bow under the weight of the joists and roof covering materials. The determining factor of post spacing is the allowable span of your beams.

Most deck roofs require separate footings from the deck to support the weight of the roof throughout the seasons.