[Dutchoven]

Hi mmmhumous,


For info: I'm using red bick (engineering grade B) for everything except the hearth...I am concerned here because your bricks are not solid bricks and I am not sure how they will hold up for you...
I'm using an arched roof rather than a dome and plan to have a tiled roof for the external wall...your planned design should work well
and up to now have been using blue cirle mortar (1:1:6 cement:lime:sand)....you should probably include 1 part fireclay into the mortar mix
Questions

1)wrt to the hearth: I plan to lay the 1st coarse of the extermal wall and use this in place of a form, for a 1-2 inch/ 50mm thick layer of 1:5 cement/vermiculite. Once set I was going to lay the firebricks on builder's/sharp sand on top of this insulation layer. will this be sufficient?...more insulation would be more efficient...most builders here on the forum to the best of my recollection used 2 inches if it was the calcium silicate sheet and at least 4 inches if it was the vermicrete
2) I'd like to just use the blue circle mortar for the main part of the oven as well. As it's got some lime in there will it be good enough (given my choice of brick)?...as I said above you should think about adding some fireclay

3) For the insulation on/around the oven, is loose vermiculite good enough or do I need the cement/vermiculite layer ass well?...loose vermiculite is good as an insulator but might want to coat the oven with a 1 inch thick layer of refractory cement to give the oven a bit more strength...the barrel vaulted oven like you are planning thrusts on the side walls...

Hope this helps!
Dutch