Pouring hearth

[Marc Olson]

Next week I'm starting the base and hearth installation for my Casa 110. In looking at the designs provided here on the site I have a question about how to pour the hearth once the masonry base is in place. How do you keep the concrete from flowing down into the openings in the bricks? The plywood forms seem to create the hearth base at the level of the top of the bricks, but since not all bricks are filled with concrete/rebar, won't concrete flow into the remaining openings?

[RTflorida]

you have several options

stuff the voids with the empty cement bags (not an option unless your mixing and pouring the concrete youself) or any other scraps laying around.

I chose the expensive route - went to Home Depot and bought 'tin caps' that are made for this specific purpose. The cost was 11 cents each, so for less than a buck you can cap them the right way.

RT

[DrakeRemoray]

I think the old version of the plans specified using a roll of aluminum flashing to prevent this.

[Unofornaio]

Newspaper, broken pieces of block, mortar slobbers, concrete slobbers, tar paper, paper grocery bags, also work just fine..
If you are using redi mix the slump shouldn't be that high anyway as to "flow" through any of these. If you are mixing by hand use the bags and with the first batch you mix top off the webs so it sets up a bit while you are mixing the rest of the slab.
Keep in mind the wetter you make concrete the weaker it gets and the more shrinkage/cracks you get.

[JoeT62]

My family made a "time capsule" and put that down one of the holes. Of course, it might not be discovered for a loooong time!

[Unofornaio]

We did the same thing..My daughter at the time was 7 and this was great fun for her. I think it should be s.o.p. for building an oven kinda like an offering for the Pizza Gods shhhh..dont tell my mom I said "Pizza Gods" I'll have to listen to an hour long lecture something about no other gods before you (Roman Catholic ya got to love it.) anyway lets face it these things are gonna be here long after we are gone..

[CanuckJim]

Uno,

Here in Ontario at least, it was traditional for 19th century masons to bury a bottle somewhere after their work was done. I have a hand blown whiskey bottle I found in the front of the house because of this tradition. I've put all kinds of things into the walls of my house and parts of the oven: coins, newspapers, bottles, notes. Why not? Should be fun for the people who might find them one day.

Jim

[james]

If you are thinking for the long-run, you could do what the Italians do, and place a Madona. Karma insurance? :-)

The idea behind the flashing was in case the concrete ever got hot enough for a slip plane (Jim H was being very thorough), but that would never happen. I always use the concrete bags.
James

[Dutchoven]

I think I'll go all the way with this stuff on my next oven...one of each of these items and cover all bases. I couldn't say pizza god in front of my mother either, RC too...she be saying the rosary for me forever. The Greeks, Vikings and other european seafarers used to put coins into the keels of their ships as an offering to their god of the sea, Poseidon etc.. Interesting traditions.
Best
Dutch

[Marc Olson]

You can see the stand and hearth pour photos (and some limited documentation) here: supercub : photos : Building a Wood Oven - powered by SmugMug