Are these local bricks ok?

[nathanw9]

I have found 2 locations that sell firebrick in the Spokane, Wa area. Both have fire ratings that seem fine. There is one that is only 18% alumina and one that is 21%. Is that enough? Anyone have experience with such bricks? Thanks

[UtahBeehiver]

There is a good explanation in the Forno Bravo Plans appendix 2. If you do not have them yet, download them from Forno Bravo, they are only a 2-3 bucks and a good baseline for your design and the forum will give you more recent and up to date building and design practices.

[nathanw9]

Thank you for the reply, I have read those plans a lot over the last two years. It still only mentions low duty as 30%. The jump from 38% recommended to what it mentions as low duty (30%) isn’t as steep as the jump all the way to 18-21% that I have found so far.