Avoid locations at the bottom of a steep slope. If your only option is soil with lots of clay, install a French drain.

Repeat this process around the bunker area and average your measurements to get an estimate of the water table level. Don’t dig your bunker in an area with a shallow water table, which is 3 ft (0. 91 m) or less.

Designate locations for the bathroom, kitchen, washroom, and common area. Consider the furniture that you want to add, such as couches, chairs, and beds. Write or draw each item to get a feel for where everything will be located.

Standard shipping containers are 8 feet (2. 4 m) wide, 8. 5 feet (2. 6 m) high, and one of two lengths: 20 feet (6. 1 m) and 40 feet (12 m). Ask about purchasing used shipping containers for a cheaper alternative. Double-check with your landlord or landowner that you can build your bunker prior to having your container shipped. Shipping containers cost between $3,000 to $5,000 USD

Consider a bunker that is 240 feet (73 m) long and wide: it requires 1,152 bags for both the length and width—240 feet (73 m) divided by 2. 5 inches (6. 4 cm)—which is a total of 2,304 for 1 length and 1 width. This means that total amount of bags per layer is 2,304 x 2 (since there are 2 lengths and widths 2 per layer), or 4,608. Multiply the total number of bags needed per layer by the number of layers for the total bags for your structure. For example, if each layer requires 4,608 bags and you need 6 layers, you need 27,648 earthbags in total (6 x 4,608). Earth bag height will vary depending on how they’re filled. After determining how many bags you need per layer, fill up one bag and measure it’s height. Now, use this to determine how many layers you need. For example, if it’s 1. 5 foot (0. 46 m) tall and you want a 15 foot (4. 6 m) tall bunker, you need 7. 5 layers (15/1. 5). Soil costs between $12 to $18 USD per cubic yard.

Select bricks or cinder blocks if you live in an area with extremely cold weather during the winter. Purchase enough cinder blocks or bricks for each layer of your bunker. For example, if your bunker is 10 feet (3. 0 m) long, wide, and high and your cinder blocks are 1 foot (0. 30 m) long, wide and high, you need 40 for each layer (a total of 2 lengths and 2 widths) across 10 layers high for a total of 400 (40 x 10).

Use a reciprocating saw or the tip of your shovel to saw through large roots. Loosen rocks with a steel bar. Consider hiring or renting heavy equipment to dig your hole. Call 811 3 to 4 days prior to digging to make sure you can do so without damaging underground electrical structures or piping.

Although 5-35% clay works too, the ideal amount is 15-25%, so stick to that whenever possible. Don’t use heavy clay as it will contract when it dries and expand when wet. Ask a garden store worker for soils that are used for cob, rammed earth walls, and adobe blocks. Dump out any soil from your sandbags as needed to create corner pieces.

Double-check that you have enough cinder blocks or bricks for each layer of your bunker before starting. Your foundation should be the same length and width as your bunker structure and about 1 foot (0. 30 m) deep. Use a spirit level to check the leveling after every 4 to 5 bricks. Stagger each layer or brick with a half piece to give it stability.

If you’re on a tight budget and want to purchase wood, make sure you use pressure treated wood.

Cover the air vents on the surface with brush and rocks. Always start by installing the corner screws of the vents for stability. Set your saw to medium speed and always follow the outline slowly and carefully. Invest in an air filtration system for maximum air quality.

Weight the silo plastic down with gravel bags, tires, tire sidewalls, or other ballast material. Purchase 2 layers of silo plastic for extra protection. Swap silo plastic with a plastic tarp or cover for a cheaper alternative. However, bear in mind it won’t be as effective.

Use tire sidewalls as opposed to tires whenever possible to prevent water buildup and rodent habitat formation. Build a shed on top of your bunker’s entrance to conceal it. Place an outhouse on top of the entrance to your bunker. Add some bushes and rocks from your excavation.

Use batteries to power lights and radio communication for the highest efficiency. Choose diesel generators as opposed to propane or gasoline. Invest in a diesel generator 2kW or smaller to charge your batteries. Call a local power company and inquire about installation costs.

Skip the water heater if you don’t mind cold water, but remember that you’ll be missing out on hot water during the winter.

Some canned foods examples include yams, carrots, peas, green beans, fruits, chili, chicken, turkey, tuna, and salmon. Dry foods you can purchase include raisins, mangos, apples, apricots, rice, flour, nuts, cereal, granola, powdered milk, and pet kibble. Buy some crackers, beans, canned meat, dried chickpeas, and gelatin desserts. Don’t forget some comfort foods, such as your favorite candy, tea, or coffee.

Keep a stash of non-prescription drugs like aspirin, antacids, laxatives, eye wash, rubbing alcohol, and antiseptic.

Add some portable heaters for winter weather.

Stock your washroom area with toilet paper and cleaning supplies.

Purchase alcohol fuel from a marine or hardware store. Keep your utensils, pots, pans, and other cooking supplies in your kitchen area.

Add a small coffee table to make your bunker homier.