Fireclay/Sand mix under floor

[ShannonCorum]

I've seen various posts on what to put between the floor insulation and firebrick hearth. It looks like a mix of fireclay and sand with a little added water to make a slurry is the suggestion. Is this 1:1?

I have some crushed firebricks that I got when taking out the old floor. Can I use this with the sand or does it need to be fireclay?

I have a hard time getting my hands on fireclay. I think I can get a 10lb bag for about $40 from a local brick supply store, but they close before I get off work every day and are not open on weekends. There are a few other places over in Louisville, KY. But I have the same issue of not being able to get there before they close. My last bag came from a guy who had a job close to where I work and he agreed to meet me at lunch time. I doubt I'll get so lucky again. He sold me 50lbs for $50. I don't know why this stuff is so hard to find.

Lastly, is this just a thin layer of fireclay/sand, mainly for leveling purposes? It is going over about 3 inches of 5:1 perlcrete and portland cement mix.

Thanks,

Shannon

[azatty]

Re: Fireclay/Sand mix under floor

I've seen various posts on what to put between the floor insulation and firebrick hearth. It looks like a mix of fireclay and sand with a little added water to make a slurry is the suggestion. Is this 1:1?

It can be, although you don't necessarily need to add water. The sand/fireclay is simply to level your hearth, so it can be dry. I added water to mine and it turned into a weak mortar that stuck the bricks pretty well. It made leveling the hearth more difficult because of the "squishing" of the mortar into the joints.

I have some crushed firebricks that I got when taking out the old floor. Can I use this with the sand or does it need to be fireclay?

There's a thread from 2007 on this board that discusses this very question. Firebrick dust from cutting is frequently recycled into mortars.

I have a hard time getting my hands on fireclay. I think I can get a 10lb bag for about $40 from a local brick supply store, but they close before I get off work every day and are not open on weekends.

Are you sure that's a 10lb bag and not a 100lb bag? $40 per ten pounder is extremely expensive. I think I might have paid $15 per 80 pound bag.

There are a few other places over in Louisville, KY. But I have the same issue of not being able to get there before they close.

Do they deliver? Got a friend who works closer?

Lastly, is this just a thin layer of fireclay/sand, mainly for leveling purposes? It is going over about 3 inches of 5:1 perlcrete and portland cement mix.

Yes. All you're doing is making a level bed for the hearth. If you were building over ceramic board, you might not even need the sand/fireclay mix.

[boylanta]

Re: Fireclay/Sand mix under floor

I used the sand/fireclay without adding water.
I opted w/ this method to keep the ceramic fiber board dry.
It worked well for me.
See my method:

http://www.fornobravo.com/forum/21/m...t-18900-3.html