How to Brace the Roof to Replace Porch Joists

Walk under the very edge of the porch roof eaves and hit the soil repeatedly with a hand taper tool to tightly compact it. Compacting the soil is required to prevent the soil from settling after you install the support braces.

Lay a 2-by-8-inch board on the ground directly under the eaves of the roof over the compacted soil.

Measure the distance between the top of the board and the bottom edge of the rafter that runs along the front of the roof. Most boards come in a maximum of 8 feet, so if the height is greater than 8 feet, an additional hydraulic jack is required.

Place a hydraulic jack on top of the ground board at the left edge. Place additional jacks under the location of each porch rafter.

Raise a 4-by-4-inch wooden post into the vertical position and lift it up until the base rests on top of the jack.

Hold the post in place while another person pushes the jack’s lever up and down to raise the jack. Stop raising the jack when it is snug against the roof. Repeat the process to install additional posts on top of each remaining hydraulic jack.

Wait 15 to 20 minutes and examine the posts to ensure that the top still maintains snug contact with the porch roof. If the soil settles under the braces, raise the jack up further until the posts are snug.