We constructed a pizza oven with refractory brick and cement. After heating it up, some of the cement joints have cracked and leak. We didn't study the placement of the chimney or vent, so we have one in the back left, as seen pictured in many examples on the internet, but the oven smokes alot while building the fire. The oven does get hot - up to 800 degrees or more, but it is a hot smoky business using it. Also the leaks are there. Should we cover our beautiful brick with cement? Should we try to add another vent? How can we make this oven work better? We also have trouble with the pizza dough sticking to the bottom of the oven. Even though the oven registers at 700 degrees or more, after several pizzas the dough starts to stick. Thanks for any comments.