How to build a survival home from cob yes, cob the ancient bricks made from mud, straw, and grass that the Romans used.
Step 1: The first element in the cob equation is mud. High quality mud is essential if you want to make the good stuff, and the best mud has a high concentration of clay. How to determine the good mud from the bad and the ugly you ask? Well, that’s relatively easy: if you make a ball from the potential dirt which retains its initial shape, that’s the droid you’re looking for (yes, I am a big Star Wars fan). You’ve struck gold, and you can go fill a bucket (or more if you’re planning something big) with this mud.
Step 2: You must harvest/gather a respectable armload of straw or dry grasses and cut them into lengths of six to twelve inches.
Step 3: Next, you must add water to your clay in order to hydrate it enough to a point/density where it will squish relatively easily through your fingers. Don’t hydrate it too much though; the ideal consistency is if you can mold it and it still hold its shape.
The stuff must not be so watery that it will run through your fingers. You just have to homogenize it pretty well. If you want to use the survival cement as a mortar for a stone-made construction, you should strive for a wetter mix; if you’re looking for building bricks or a solid structure made of cob, go for a firmer mixture.
Step 4: You should spread something like a tarp on the ground and put the bucket of homogenized mud and the cut grass/straw at the edges.
Step 5: In the next phase, you must dump the mud from the bucket in the middle of the tarp and put about half of the straw/grass on the top (step five, but who’s counting anyway?).
Step 6: In the next step you must fold a corner of the tarp over the top and stomp it pretty well if you’re barefoot or begin to directly stomp the straws into the mud if you don’t have a problem with getting dirty.
Step 7: Next, after you’ve danced around a bit and the mixture isflattened and spread out, step off the tarp then fold it in half, thus turning the mixture back onto itself. You should repeat the procedure at least 2-3 times until you form something in the shape of a ball. Then, you must add the remaining strawor grass progressively and start stomping again, until the remaining grass homogenizes with the mud thoroughly. As a general rule of thumb, the optimum grass/mud ratio is somewhere between forty and sixty percent grass, depending on the type of the structure you want to build.
Step 8: The last step is to start your survival cement project as soon as possible. Don’t let the cob sit to dry out because the mud will harden and it’s going to be very difficult to get it into your desired shape or form. Basically, you can start building bricks with the cob/survival cement and you can repeat the aforementioned procedure until you have enough (bricks or whatever you’re doing).
If you have to add water to help with the re-hydration of the mud, keep in mind to add a little at a time, to avoid making the cob soupy and thus unusable. It’s way simpler to make the cob a little wetter than to regain its original consistency by adding mud/straw.
If you want to build tougher cob, remember to place the grasses or straw parallel to each other for creating a re-bar like effect, making for a stronger building material.
Since a picture is worth a thousand words, below’s a video-tutorial in high-definition about how to make survival cement/cob using natural building materials, step by step. The most important thing in the process is to learn how to disseminate good mud/clay from bad, since mud is the main building block in the recipe of high quality survival cement. If you got that part figured out, the rest is easy as pie.