I have made my fireplace recess bigger by taking several bricks off in order to be able to accomodate a woodburner. I have noticed that some bricks are laid upside down without mortar inside the bricks or not much mortar around those bricks. I am more concerned around the top horizontal area of the recess where the flue starts where I am thinking of putting mortar between the bricks to make it stronger (the flue itself is ok). I will then need to put a lintel at the front. Is there a particular reason why it was built that way?
Thank you.
Thank you.