Quck answer
Building underground shelters with cinder block construction is a practical and effective way to protect yourself and your loved ones in times of emergencies. Cinder blocks are affordable, readily available, and provide excellent structural integrity.
To build an underground shelter with cinder blocks, start by selecting a suitable location and excavating the area. Create a strong foundation using gravel and concrete. Lay the cinder blocks in a staggered pattern, ensuring a tight fit and using mortar to secure them together. Install reinforced steel rods for added strength.
Add ventilation, waterproofing, and insulation to the shelter to ensure comfort and safety. Finally, cover the shelter with a layer of soil or other materials for added protection.
Remember to consult local building codes and regulations, and consider seeking professional assistance for complex projects. With proper planning and construction, you can create a durable and secure underground shelter using cinder blocks.
Underground shelters are created to prepare for nuclear attacks, tornadoes, civil unrest, and for storing food when not in use. Regardless of the original purpose, it is important to build a strong and durable shelter. Cinder block constructions are known for their durability. These shelters are able to withstand high winds, flying projectiles, and to some extent, radiation. However, they are vulnerable to flooding and leaks if they are located near the water table.
Planning for the Underground Shelter
Step 1: Research Licensing and Permits
Find out about the necessary licenses and permits required for building the shelter. The need for a permit depends on the laws specific to your area. Some people prefer to keep the construction a secret, while others obtain permits to simplify the process.
Step 2: Develop a Shelter Plan
Determine the location and size of the shelter. It should be situated far enough away from trees and buildings that could collapse on the entrance, trapping people inside even after the danger has passed. The shelter should also be easily accessible to everyone in the family. The Federal Emergency Management Agency (FEMA) suggests a 10-foot by 10-foot shelter as an appropriate size for temporary use by up to six people. Adjust the size of the shelter based on the number of potential occupants.
Step 3: Decide on the Construction Method
Select the method of building the underground shelter. The most direct approach involves excavating the dirt to create a hole slightly larger than the desired structure. However, this method may pose challenges in terms of material delivery to the bottom of the hole. Another option is to build the structure above ground in a natural valley on the property and then cover it with dirt upon completion. This method allows for easy access to each wall and facilitates material movement within the shelter.
Commence Construction
Step 1: Excavate the Hole Using a Back Hoe
The hole should be 3 feet wider and longer than the actual shelter dimensions. It should also be at least 2 feet deeper than the height of the shelter to accommodate a solid roof made of concrete and soil.
Step 2: Frame the Shelter Foundation
The foundation should be 8 inches wider and longer than the shelter dimensions. Place an 8-mm moisture barrier at the bottom of the hole and construct the foundation frame on top of it.
Step 3: Install the Posts
Install 2-inch square posts every 18 inches along the length and width of the foundation. Use 3/4-inch plywood boards and secure them to each post with three 2-inch self-tapping screws.
Step 4: Add Reinforcement Steel to the Foundation
Arrange rebar in a checkerboard pattern within the foundation frame. Use a hammer to drive rebar stakes into the ground and secure the rebar in place.
Step 5: Adding Cement to the Foundation
Contact a professional cement mixer to pour the cement into the foundation. Before pouring the cement, it is important to have a concrete professional inspect the frame for strength, as this will be the most expensive part of the shelter. Allow the cement to dry for a week, allowing for natural expansion and contraction, before laying the cinder block.
Constructing the Walls
Step 1: Installing the Door Frame
Secure the door frame by using concrete bolts driven into the foundation. The cinder blocks will be stacked around the door frame.
Step 2: Placing the Cement Blocks
Using a mason’s trowel, spread mortar along the edges of the foundation. Press each block into place in each row, with each row of blocks known as a course. Before placing each block next to another in each course, spread mortar along the sides of the block. Staggering the pattern of blocks is optional, as the spaces in the blocks will be filled with cement to strengthen the walls. Repeat the process of laying blocks until the desired height is reached. Allow the mortar to dry for three days.
Step 3: Applying a Moisture Barrier Spray
Apply a generous layer of moisture barrier spray to the exterior of the walls. Allow it to dry, and then apply two more coats of spray.
Step 4: Reinforcing the Walls
Fill the empty spaces in the cinder blocks with poured concrete to enhance the strength of the walls.
Step 5: Installing a Ventilation System
Using plumbing brackets and concrete screws, secure a 2-inch PVC pipe in each corner of the building. These pipes should extend 3 feet beyond the roof of the shelter and at least 3 feet into the shelter. They will serve as the shelter’s ventilation system.
Constructing the Roof
Step 1: Installing and Anchoring Plywood
Attach 1-inch plywood to the top of the cinder block walls using 3-inch concrete screws. The plywood should cover the entire shelter.
Step 2: Installing Sturdy Support Beams
Secure four 4-by-4-inch support beams on the inside walls of the shelter, next to each corner pipe. Use “L” brackets to attach each beam to the ceiling, drilling screws through the brackets at each hole. These support beams should extend from the floor to the plywood ceiling inside the shelter. Additionally, place three more 4-by-4-inch support beams in the center of the shelter: one against the left wall, one against the right wall, and one in the exact center.
Step 3: Leveling the Beams
Ensure that each beam is level and keep them in place using “L” brackets. Once a beam is properly positioned between the floor and ceiling, attach an “L” bracket to the top of the beam and secure it to the ceiling with self-tapping screws. The center beam can be removed once the concrete roof is dry, or it can be left in place if desired.
Step 4: Strengthening the Roof with a Moisture-Resistant Barrier
Similar to the foundation, lay down a moisture barrier and pour a 1 1/2-inch thick layer of concrete for the roof. It is recommended to consult the concrete professional used for the foundation. Allow the concrete to dry for three days. Your shelter is now ready for use.
