"Sand and gravel" hearth construction

[spangler]

The Hearth-Wiki says that "sand and gravel" = R-.59 in a hearth construction...
Any more specific description of this?
ANY type of gravel...??
What's the ratio of sand/gravel...??

Thanks!

 

[jtp10181]

I think that's the old school way, making a footing and filling it with sand and gravel. Then not sure what they did on top of that? More cement, then tile?

Don't know why you would want to do that now, just get a piece of micore.

 

[spangler]

Thanks, but yeah, just trying to BE old school.

I happen to have sand and gravel laying around in the yard, just wondered about the mix-ratio...

 

[Martin Strand III]

The Hearth-Wiki says that "sand and gravel" = R-.59 in a hearth construction...
Any more specific description of this?
ANY type of gravel...??
What's the ratio of sand/gravel...??

Thanks!

Why not use brick or some natural stone?
What are you trying to accomplish?
Do you want high heat retention (insulation) or high heat transfer (like metal)?

Aye,
Marty
Grandma used to say, "The devil is in the details."

 

[spangler]

I am trying to keep a low hearth-extension profile.

According to Hearth-Wiki: 1" of sand-and-gravel has an R-value of .59 -- 3x as much as the .2 for an inch of brick, and 6x the .1 for an inch of slate.

Just wondered if anyone out there knew the suggested composition of the sand/gravel mix...? Could it be pure sand? -- or pure gravel? -- and what grade of gravel? -- or what ratio of sand-to-gravel?

Figuring I could lay a slate slab on top of the stuff.

Not rocket-science I guess, just trying to keep it simple.

Though, now I do have another question: As things stand now, the center of my Hearthstone Homestead -- w/6" legs and a heat-shield -- will be on 4" bricks above 6" of concrete (the original fireplace hearth) -- which rests on the three 2x6 floor-joists in the basement below... I'm figuring that's only about a 1.5 r-rating between stove and joists (the Homestead asks for R-2.5... Is there any kind of heat-deflection system I can set up in the immediate space beneath the stove?? (A solid form of sand/gravel, maybe...?)

Was kind of hoping I wouldn't have to raise the entire hearth (I only have about an inch of play to get the stove-pipe back to the 'T' in the fireplace)...

I know micore is what everybody uses, just trying to think of other ways.

Thanks again for any thoughts.
spangler

 

[Backwoods Savage]

The ones I've seen were all sand or about a 60/40 mix of sand and gravel. Not sure if this is the right percentage but sand would work. If that is doubted, then build a fire on sand; after several hours when some of the coals are still there, then dig down into the sand about 3" and see what you find. I'm betting it will be cool; not cold but not warm either.

 

[Backwoods Savage]

btw, I should have added that all I've seen done that way, they then laid a layer of brick on top of the sand/gravel.