I’m planning on adding standard brick to front of oven.
I would like to partially close front-about 1” or so overlap
I have noticed some posts say to use fire brick and high heat mortar
Some say standard brick 
and standard mortar would be ok .
What would be best ?
Don’t want to make a mistake .
Hi Erminio!
As always, glad you asked first. In this case, everyone’s right…but could be “right-er.” 
The front of the oven is mostly outside the fire envelope. It gets hot, but not like the barrel or the area right around the chimney.
- Standard mortar and standard bricks would be okay in that area.
BUT
- Standard mortar will eventually break down. (We’re talking a couple of decades from now.) The bricks will be okay.
So I’d go with high-temp mortar, for the same reasons that you can choose to use it with the hearth frame bricks. The areas that will be exposed to fire, especially across the top of the closure, will be fire-cured rock hard. The other areas will still cure, and though the mortar won’t reach the strength that it would in direct flame and high heat areas, it will be strong enough to support your structure.
If you’ve been using the home-made mix, this is a good area for it because it will be about the same cost as a bag or two of standard Type S.
Good luck, and looking forward to seeing photos of that closed-off front!
use fire brick it will maintain more heat