Good Afternoon, everyone. I am a trainee from FL. The pictures and a diagram is for a fireplace at my home built by Majestic Huntington, In. The model number is MBU36. As I inspect this fireplace to complete one of the pre-licensing courses, I noticed a 1/8th gap between the back brick and left side brick wall. When I shin the flashlight, the metal cabinet behind the gap shows no sign of deterioration. Is this a defect even if the metal cabinet seems to be ok? If it is how should I write on a report? Thank you very much.
Chimney Safety Institute of America recommends replacing (not repairing) the refractory panels if the cracks are large than 1/16" or if you can insert a nickel into the crack. The panels are meant to protect the metal cabinet, so they should always be maintained in top shape. CSIA Level II inspection is always recommended after homeownership change.
Yep, this is beginning to be a habit 
, I agree with Simon. 
Nothing wrong with having healthy habits 
I’ll hold you to that…I need it. 
Thank you.