What to do with Insulating Fire Brick

[jeemann99]

I was given a bunch of Insulating firebrick, but do not know where to use it.

Can I use it to line the inside of my outdoor fireplace I want to build? or do I need to use the same firebrick I used for my oven to line inside of fireplace?

thanks in advance

[Gulf]

You will need to use firebrick to build the firebox. The "insulating" fire brick can be used as a "filler" or "backer" brick between the firebrick and supporting face brick. That is to the sides and back of the firebox.

[david s]

Insulating firebricks are ok to use in contact with direct flame. In terms of their resistance to thermal shock,they are just as good if not better than dense firebricks. They are however, not as strong as dense bricks and can be easily damaged by metals tools or large chunks of wood. They are also unsuitable for the floor or dome as they don't have high thermal mass.You could use them over the top of the dome or under the floor although it is an expensive way to do it unless you got them really cheap or free. As insulation behind your fireplace they would be an excellent solution.

[Neil2]

Save a few for use as a "thermal break" for the entryway.

[david s]

Originally Posted by Neil2

Save a few for use as a "thermal break" for the entryway.

Yes they will work as a thermal break, but they won't work as an expansion joint to relieve expansion stress. I think something like vermicrete is better for this purpose.