For further stability, you could dig into the ground and start the bricklaying there.

You begin by laying your bricks on wet sand, and filling in with cement grout.

Then, you will continue building this stove up, and laying rebar on your 2nd or 3rd layer.

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Image By: Garden Design Via YouTube

This stove is an excellent step for my familys emergency preparedness plans.

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How To Build A Brick Stove - Disaster Preparedness - Outdoor Rocket Stove