How my cob and stone hearth performs

We're about halfway through winter in the Ozarks and I've been living in our "Cobin" full time since October.  One of the big experiments was a cob and stone hearth for the little tent stove we have in there.  I wasn't sure how it would hold up to the thermal shock.  It's done really well, no cracks and it holds enough heat that the room stays warm for several hours after the fire goes out.

The real test will be this next week, close to 0 degrees at night.

Very nice looking, Sherry!
That looks like a good spot to build a 4 or5" mini batchbox masonry heater!

thomas rubino wrote:Very nice looking, Sherry!
That looks like a good spot to build a 4 or5" mini batchbox masonry heater!

The only thing about doing that would be the weight...it's just sitting on the kitchen counter.  We figured that we could take the stove out in summer for more counter space.  😊

Looks good, Sherry!

Question for you about your cob composition... How much straw would you say is mixed into your cob, compared to sand and clay?

Stephen B. Thomas wrote:Looks good, Sherry!

Question for you about your cob composition... How much straw would you say is mixed into your cob, compared to sand and clay?

Thank you! I use our subsoil as it. I simply screen it through 1/4" hardware cloth first. I did try it without screening during one rainy spell and the decomposed granite sliced my toes like a razor blade while I was mixing it.

For straw, I use the chopped straw for grass planting from Lowe's.  I would say I only have 15% straw by volume. I add three big handfuls to 2 5 gallon buckets of earth.  That's all I can handle at a time.

This does crack a bit if it is applied less than 3" thick or very wet. You can see that from the rough plaster on the wall. For the finish plaster, I'll use 1:1 earth and sand mix and then add that 4 parts to 1 part cow manure.  

Hope this helps!

Sherry,

Great idea on the little stove. How many sqft are you able to heat with it?

We have one we use for hot tent camping and I use it to heat a portion of the barn.

Josh Hoffman wrote:Sherry,

Great idea on the little stove. How many sqft are you able to heat with it?

We have one we use for hot tent camping and I use it to heat a portion of the barn.

So our little Hovel is only 6'x9'.  It's fairly well insulated and the cob covered walls provide a goodly amount of thermal mass.  We almost always have to have the window open when the stove is going, so I'm sure it would heat a space larger than this one very well.  For the $80 I paid for it, it's surprisingly heavy and well constructed.  We did purchase the damper pipe separately since we wanted a little more control of the flame than just the front vent slide would give us.  The window is okay, but soots up fairly quickly.  Still that's okay because by the end of the day, I want it dark in there anyway.