Refractory bricks are generally yellowish-white in color. They have excellent thermal resistance and great compressive strength. Their chemical composition drastically differs from the chemical composition of normal bricks. Refractory bricks contain around 25 to 30% alumina and 60 to 70% of silica.
It's going to get rain driven at it from every direction, and despite your best efforts in sealing the dome with our roll-on render coating and fitting the water barrier system, if the firebrick front of the oven is exposed to rain then the firebricks will absorb that rain and draw it into the oven.
