I built my oven about 5 years ago. I left the entrance as plain 1/2 cement board and as you can see it starting to show signs of wear. I want to build a new entrance surround and I have some questions.

1) Materials - given the heat should I build it out of 1) limestone 2) refractory concrete 3) or a standard concrete limestone substitute.

2) Design - given expansion and contraction can I make a cast, solid "picture frame" type of surround or should I do a four piece, mitered and mortared corner type of surround?

3) Adhesion- I'm envisioning cutting out a 4" wide section of the 1/2" cement board around the opening. This will expose the face of the cast oven entry and the bottom hearth brick. What type of adhesives are available to adhere the surround in place.

Thanks in advance for your thoughts