Why not curved lentil as oven opening?

[KISS4me]

Clarification appreciated. Now have hearth layers clear and will incorporate 2-3 weep holes in concrete using 1/2" pvc pipe. I take it you dont leave pvc pipe in, hence the use of rebar to knock out when concrete is fully cured.

[UtahBeehiver]

You leave the pvc sleeves in just knock out the thin 1/2" top portion of the concrete with rebar or a metal rod. You plug with pvc with some newspaper or such

[KISS4me]

Thanks for double explaining - I get it fully now

[KISS4me]

Progress has been very slow, but back into it now. have started doing limestone rock inlay in base and am assembling materials and ideas for hearth pour. Update photos are available at https://www.flickr.com/photos/129613...57715344888848

[MarkJerling]

At least you're out of the ground! Progress. COVID lockdown delayed my start but, other than the door, I'm done!

[KISS4me]

Have put in a few hard days on oven build. Progress has been slow, but have stand walls completed and well into hearth form work. Took me a full day to get base in place and outside box frame. Can't remember it taking this long last time! Next step is getting the reo (and two weep holes) in place ready for pour. Planning 3.5" concrete and 4" perlite/vermiculture mix. Mixing and shovelling concrete into mold is feeling like hard work.
Photostory here: https://www.flickr.com/gp/12961365@N00/5f03PG

[MarkJerling]

Sounds like hard work! I found a Readymix truck made life much easier. LOL

[KISS4me]

Thought about getting concrete in, but have a mixer and need to toughen up! Have spent half a day preparing the reo and filling gaps (mainly due to using rock in walls. Seem to be using a fair bit of newspaper and cardboard.
Check photos and any observations/feedback pre pour greatly appreciated. I would be on shattered bloke if this leaked everywhere or worse still collapsed. Still need to set up weep holes and planning to use a bit more duct tape to seal various small gaps.

Link to photos: https://www.flickr.com/gp/12961365@N00/9at0L4

[Neil.B]

Great job so far, well done.
Is your hearth big enough, it only looks about 48" wide.

[KISS4me]

1500cm or 60" wide. Should be enough.

[MarkJerling]

Thought about getting concrete in, but have a mixer and need to toughen up! Have spent half a day preparing the reo and filling gaps (mainly due to using rock in walls. Seem to be using a fair bit of newspaper and cardboard.
Check photos and any observations/feedback pre pour greatly appreciated. I would be on shattered bloke if this leaked everywhere or worse still collapsed. Still need to set up weep holes and planning to use a bit more duct tape to seal various small gaps.

Link to photos: https://www.flickr.com/gp/12961365@N00/9at0L4

Looking good!

[KISS4me]

Poured hearth concrete yesterday and keen to remove supporting boards from underneath to punch out weep holes and then do layer of perm/verm mix.
My question is about the timing of board removal - Is 40 hours adequate? A collapse or slump would be devastating.

[MarkJerling]

Poured hearth concrete yesterday and keen to remove supporting boards from underneath to punch out weep holes and then do layer of perm/verm mix.
My question is about the timing of board removal - Is 40 hours adequate? A collapse or slump would be devastating.

No, much too quick! Leave for a minimum of 7 days. I left mine for 28 days which is excessive, but concrete gains most of it's strength between 7 and 90 days. At 40 hours (less than 2 days) you still have a very, very weak "green" slab.

[KISS4me]

Well timed advice Mark as I was about to remove form tomorrow. Much appreciated. Will wait.

[MarkJerling]

Well timed advice Mark as I was about to remove form tomorrow. Much appreciated. Will wait.

Better safe than sorry!