Will an oven fit....looks like yes! PA build

[mk e]

Ahhh.....I posted all the pics at once so timing is not clear. That silly round base I though was a good idea took me 3 weeks to build and now another week to build up to match the dome diameter. The vermiculite slab went in July 2 and is covered by a 2 5" concrete slab, leaving just the sides open to the elements to pick up new water. Then a broken truck and his daughter's wedding kept my bother away until september so it's been sitting a long time and should be pretty dry.

I did add some vermiculite to the stucco covering the insulation...it's about 50/50 motar/vermiculite by volume and about an inch thick, except near the chimney where its thicker to form the radius that blends it into the dome. No doubt that still has some water but is was at least a full day in the hot sun between 1/2" thick layers...but it looked and felt pretty dry each layer.

Still, probably good advice to heat it slowly.

It is a 40" oven btw, I didn't mention that.

[david s]

It isn’t our intention to worry you but caution and patience are advised. Vermicrete takes up an enormous amount of water in the mix and less than half is used up in the hydration process This leaves a lot of free water to eliminate. Not sure how big your oven is but a 4” x 1 m vermicrete slab is around 79 litres (20 gallons) 1/3 of which is water. When you build straight over it without allowing it time to dry some, it makes the job of drying it that much more difficult. Some drain holes in the supporting slab help to eliminate moisture more easily. The same applies for the mortar in the inner dome and the vermicrete in the insulation space. So just take your time with gentle fires. Remember, one litre of water makes over 1650 litres of steam.

[mk e]

Looks fantastic, really interesting build.
Moisture is a real bugbear, it is truly amazing just how much water you can lock in the dome and base...

Thanks.

You guys are starting to get me nervous.....I'm pretty sure that even if the mortar holding the bricks cracked I'd never know because once they are set there's no place for them to go. I'm also not sure about the dome cover....with wire on the inside and fibermesh near the outside I'm not sure if it can go anywhere either and with 4.5" of brick then 2" insulation under it it's going to see WAY less heat than inside the oven so I'm not really sure how much moisture trapped in there matters structurally......but now I'm thinking I may just run the hot air gun in the oven for a bit (like a few days) before I light any fires. That would get the inside up to 100-150F pretty easily I think and water won't stay long at those temps. Maybe the 1st week of Oct once everything is pretty much cured.

[fox]

Looks fantastic, really interesting build.
Moisture is a real bugbear, it is truly amazing just how much water you can lock in the dome and base,
I use a 4” vent in the very top of the dome that has a close fitting cover but it is amazing how much steam the vent can let out on a new oven.

[mk e]

The base is about done. ...its not out more than 1/4"at this point I don't think. If there is ever a next time I'll make sure the base is not smaller than the finished dome....this was awful.

I had a little mud left so I also brown-coated the woodbox.

[mk e]

Tonight I got another coat on the base. I got the level out, marked the low spots and trymied to get them filled

[mk e]

Thanks and yes it will be sitting a bit while I work on finishing up the exterior, retaining walls and island. I'm thinking first fire while be about Oct 6 so it will have a full month to dry. It's been so wet I figured better to get the thinset layer on to keep new water out rather than worrying about keeping old water in. Either way, it will have had a month to dry.

[david s]

Nice work. As you have gone straight onto the outside shell before doing any drying fires first, you will have locked a substantial amount of water in the insulating layer because 1/3 of the volume of the vermicrete is water. Sudden expansion can cause cracking of the outer shell. Also because the outer shell has been made with a cement render it does not achieve full strength for some time. 75% after one week is about normal. You can enhance its strength by covering it for a week to retain the moisture. In your case, particularly as you’ve built it so quickly, you have a lot of moisture to remove, therefore a vent somewhere in the outer dome shell would help. Rather like a saucepan with a hole in the lid, it will allow the release of moisture vapour and a release from pressure build up. Right now you will be itching to get some fires into the thing and get cooking, but it is precisely now that it is prudent to give it some time. When you do start the drying fires take them slow, if you see visible steam you are going at it too hard, back off. Good luck.

[mk e]

There was a slight miscalculation on how big the outside of the dome would endup... so it once hung the base by 1.5-2" per side.......lots of mortar on the base...and not always getting it covered fast enough as the rain begins.

You're all caught up now. Last night was coat 3 on the base and its pretty close to right....one more coat I guess, hopefully tonight.

[mk e]

Next came a layer of fiberglass mesh held on with thinset and I'm thinking it's starting to look pretty good.

[mk e]

I did a 3rd coat to straighten it...not bad

[mk e]

With that my brother left and headed back to Texas leaving the rest to me. Here's coat 2, looking better

[mk e]

Another pic

[mk e]

Day 3 was a quick coat of mortar followed by 2" of insulation, chicken wire and a first with a mortar/ vermiculite mix.

[mk e]

Day2 also brought a chimney. It turns out we really hadn't talked much about the option here and Sunday on a holiday weekend after discussing everything that can be done it became clear the only thing that could be done today was makes something fron the extra fire bricks we had so that's what we did.