Sorry for the brickwood post. But as others. I have invested an enormous amount of time building this thing and have trouble reaching or keeping high temp. So.... In researching I wanted opinions on this mod before I mortor this in. I am trying to achieve about a 60% cut off right before the chimney. Will this help? The floor is setting on a slightly larger than standard firebrick base with 1.5" of sand and 2.5" of vermiculite and Portland. Thanks for looking