How to Support a Freestanding Porch

Mark the corners of the porch with stakes. Square the outline by measuring from corner to corner with a tape measure. Adjust the stakes until the diagonal distances are the same.

Rake the area to clear it of debris and get it level. Lay plastic or similar membrane over the enclosure to block moisture and weeds and then secure the membrane with a few inches of gravel.

Dig holes with a posthole digger at the corners to set precast concrete piers with the beam supports attached. Dig the holes below the frost line, the depth at which the ground freezes, or at least 2 feet deep.

Set the piers in the holes with the beam holders aligned in the direction of the long side of the porch. Use a tape measure to get the proper distance and a level to ensure they are plumb and the tops are level.

Install 2-by-6-inch band beams on the long sides of the porch. Fasten beams to the holders with galvanized screws and a screw gun. Use one screw in each hole in the holder, taking care to have the ends even with each other. Fasten 2-by-6 end beams across both ends of the band beams with galvanized screws to complete an outline frame.

Fasten metal joist hangers for 2-by-4-inch joists between the two side bands. Screw the holders to the bands at 24 inches apart with galvanized screws. Set the 2-by-4s in the holders on edge with the 2-inch length face up.

Screw them in place through the holes in the sides of the hangers. Lay a long board with a level on it across the outline. Adjust the joists as needed until the floor area is level.