A lally column is a steel pipe filled with concrete that is installed as a support for floor beams. The standard lally column is 8 feet long and 4 inches in diameter, but it can be purchased in other lengths and diameters. The column, typically installed in a basement, rests on a steel plate on a concrete floor footing. Another steel plate at the column's top supports the beam.
Things You'll Need
Tubular concrete form
Heavy hand hammer
Rotary power hammer
¼-inch steel plates
10-ton hydraulic jack
4-by-4 inch post
2-inch lag screws
Lead screw anchors
Installing a Lally Column
Determine where you need the support of a lally column. Mark the beam at that spot. Center the string of your plumb bob on the beam and lower the bob to the floor. Mark the spot where the bob touches. Draw a circle on the floor 12 inches in diameter, centered on that spot. If the floor is concrete, rent a rotary power hammer and use it to break up the concrete in that circle. Undermine the concrete at the edges of the hole using your shovel, and break off any jagged edges using the heavy hand hammer. If your floor is dirt, just start digging.
Dig the floor hole 2 feet deep using the shovel. Cut the 12-inch tubular form so that its top is just below the bottom of the concrete floor. Place it in the hole. Make sure the form is centered right below the support location and is level. Mix enough concrete in the wheelbarrow to fill the tubular form. Pour or shovel the mix into the form until it is full to the top. Allow the concrete to cure for at least a week. Backfill with dirt around the concrete form, leaving the top clear.
Set up the hydraulic jack and post right next to where the column will go and lift the beam slightly, not more than 1/4 inch. Measure the distance from the bottom of the beam to the top of the filled tubular form. Subtract ½ inch from the vertical measurement to allow for the ¼-inch square steel plates at each end of the column. Obtain a lally column of the correct length, with the steel plates welded to each end of the column and 3/8-inch holes predrilled at the plates' corners.
Set the column in place on the footing. Make sure it is set square and plumb from two sides. Mark the location of the steel plates' holes on the beam and on the floor. Pre-drill pilot holes in the beam 2 inches deep. Drill holes 2 inches deep in the footing and insert lead screw anchors. Set the column in place and lower the beam onto the column's top. Secure the top to the beam and the bottom to the floor with the lag screws. Fill the depression around the column foot with concrete up to the floor level.