Double-wide trailer footings are essential to consider when planning for setup. They provide a great base for construction material when you are planning on laying block or brick for underpinning. They can be time-consuming to dig and pour, but with a little preparation, the job can be completed in a day or two.
Measure the length and the width of the double-wide before it is delivered on site. You will need to know this when planning the footer.
Locate the first corner of the footer and drive a 2-by-4 stake into the ground. This can be anywhere you choose, as long as there is enough room for the other corners in reference to the first one.
Measure across from the first point the width of the double-wide. Add an additional 12 inches for extra footing and drive another 2-by-4 in the ground. This is done to allow tolerance for the placement of the double-wide when it is delivered.
Stretch and tie off the nylon twine from point one to point two without cutting the twine. Just tie it off and allow it to lie beside the second point for now. Measure from the second point the length of the double-wide and add 12 inches for the tolerance factor.
Square these three points using the 3, 4, 5 triangle method. Begin at the second point and measure back to the first 3 feet. Make a mark on the twine at 3 feet. Back at the second point, measure down the length 4 feet and make a mark on the twine. With a helper on the third point, holding the 2-by-4 stake at the desired length with the twine wrapped around the stake, and a helper at the 3-foot mark holding the tape measure, pull the tape measure at an angle and out to 5 feet. The corresponding 4-foot mark should line up with the 5-foot mark on the tape measure. If it doesn't, have your helper at the third point adjust his end so that they align. You now have one-half of the layout squared. Repeat these steps until you have made it all the way around the footer.
Dig the footer in line with the twine that you set up in the previous step. The footer should be 8 to 12 inches deep, 24 inches wide from the twine inward, and should be checked with the builder's level every 4 feet to ensure that the footer remains level.
Drive the 1/2 inch re-bar into the ground at 4-foot intervals inside the footer. The re-bar will come in 2-foot pieces and you should drive them half-way in at first. When the re-bar has been set, go back and begin at one corner driving the first piece of re-bar down until 6 to 8 inches remain above ground. At every piece of re-bar, drive the piece down until you get within a few inches above the last one. Use the builder's level to check all the re-bar in reference to the original one.
Spray the tops of the re-bar with the orange paint. This will help you locate them when pouring the concrete.
Figure the concrete.Take the two lengths and the two widths and add them together. Multiply that number by 2 (footer width in feet) and that number by .75 (footer depth in inches). Because we must stay within the same units of measurement, .75 corresponds to an 8-inch footer. Divide that number by 27 and you will have the cubic yards necessary for pouring the footer. If you are not comfortable with figuring the concrete, have the concrete provider figure the concrete.