After a long winter, we moved back into our camper in March. I realized that I didn't have enough limestone to bring the foundation up to 18" above grade which is recommended for cob. I took up the limestone that I had put down in the fall and did two courses of old concrete (urbanite). I mortared these with readymix and then put down the limestone which I mortared with Type S mortar mix. This has lime premixed and is much more plastic and fun too work than basic cement mortar. We started cobbing on June 1st. Here we are finishing the first course of cob on top of the limestone.