How to Form a Foundation for a Quonset Building

Form a simple foundation and slab and fill your forms with concrete. You’ll have the ideal base for your new storage shed.

1. Measure the dimensions of your Quonset hut using the tape measure.

2. Mark out the measurements of your Quonset hut on the ground where you’ll be placing the shed. For instance, if your Quonset hut measures 5 feet by 7 feet, you’ll pound a metal or wooden stake into the ground where one corner of the shed will be, measure 5 feet over and pound another stake into the ground; measure 7 feet from the second stake and pound another stake into the ground; measure 5 feet from the third stake and pound the final stake into the ground so that you have formed a rectangle the exact size of your Quonset hut.

3. Measure inside the rectangle from one corner to the diagonally opposite corner and make note of the measurement. Do this again from the opposite corner to its diagonal opposite, so that you’ve measured over an invisible “X”. Both measurements should be the same. If they are the same you know that your rectangle is perfectly square and you can continue forming your foundation. If the two measurements don’t match, you’ll need to adjust the wooden stakes until you get the same measurements when measuring the inside of your rectangle diagonally.

4. Attach the string to one of the stakes, a few inches above the ground, and run it to the next stake, wrapping it around the second stake to secure it. Continue running the string to each stake and wrapping it once or twice around the stakes, finishing up at the stake you started with. Tie the string off and cut it. This creates a visible form for your rectangle.

5. Paint a line on the ground with the marking paint, using the string as guidelines. Spray the paint directly over the string, pointing down at the ground, so that your paint line is exactly where your string line is.

6. Remove the string from the stakes, but leave the stakes in place as guidelines as you dig the footing.

7. Dig a trench 7 inches wide and 12 inches deep around the inside of your painted guidelines.

8. Remove the stakes from the four corners of your foundation.

9. Pour 4 inches of gravel into the part of the foundation that will be the slab. You won’t need any gravel in the trench around the perimeter. Spread the gravel out evenly.

10. Set the stakes, three to each side of the foundation, pounding them into the ground just outside the painted guideline.

11. Attach the 2" by 6" forms to the stakes with nails so that the forms are suspended 4 inches above the ground. Use the level to make sure that you are keeping the forms level as you go. The forms can (and most likely will) run longer than the sides of your foundation. You just need to attach the forms at the corners, butting the end of one form up against the side of the previous one you set and pounding a nail into them to hold them together.

12. Use the four remaining stakes to reinforce the corners of the foundation by pounding them into the ground on the outside of the foundation line at the corners and then nailing them to the forms.

13. Pack the dirt that you have left from digging the trench underneath the forms. Pack it tightly so that it will keep the concrete from running out when it is poured.

14. Pour 1 foot of concrete into the trench before placing the rebar strands into the footing. Place the rebar end to end, cutting it if necessary to make sure you have a continuous length of rebar running through your footing.