Raising the hearth hight up to the oven floor ?

[pnassar]

I am in the process of building a 100 Primo 2G. I am ready to poor the hearth with a bowed front ledge as in the FB installation guide. I am not quite sure how to accomplish two steps and seek the members expert advice !

First, after assembling the modular unit on the fire board do I trim the fire board flush with the outside edge of the cast modular unit and then drop the insulation down and adjacent. Or, do I let the fire board extend out and then bring the insulation and stucco down on top of the fire board surface? I think I have seen picture of both. The installation diagram looks like my first description.

Second issue. I would like to finish the top of the ledge and surface surround the oven with a grant top that ends up flush with the cooking surface of the oven. That will require material to raise the surface from the hearth top about 4 3/4 inches. The fireboard (3") plus the cooking floor fire brick (3") less the thickness of the granite (1 1/4"). What material do you recommend for this 4 3/4" lift ? Though about doing a second pour with lightweight concrete but there is probably an easier way...

Thanks greatly for all responses !

Pete

[david s]

The answer to your first issue is that it can be done either way it won't matter, so long as the oven is totally surrounded with insulation.
For your second issue I'd be using 5:1 vermicrete with maybe a little sand and clay added to make it more workable so you can trowel it off nice and flat to accommodate your granite.

[pnassar]

Sounds like a plan. Appreciate your input.

Let me throw another question out to you. For the vent/flue i prefer to use some type of masonry unit since the oven will be stucco. Is there a particular CMU or clay block that is ideal for this unit ?

Pete

[UtahBeehiver]

CMUs are not suitable by themselves for a vent, the temperatures are just too hot. Some people have use fireplace clay liners as vent. SS double wall pipe inside CMUs is possible but then the OD gets really big, Cement board around double SS will work then you can stucco the cement board. It is possible to brick a vent but I am not sure how much weight the Primo G kit can handle.