Newbie insulation question

[Nino_F]

Hi all - I have 3 year old half barrel WFO which I’d like to add more external insulation to. Currently have a single
layer of CF blanket over the barrel and render/stucco finish over that.

I’m noticing the barrel external temp gets up to 80-90 degrees Celsius when the internal temp is 400 degrees C. The oven has usually returned back to ambient temp by the morning (8-12 hours). My intention is to add additional insulation to prolong cooking time and also keep temps higher for longer when cooking pizza.

I have about 9-10cm of room/width left to support additional insulation materials on the existing oven. My question is:

1. Should I cover with 3-4 inches of vermiculite cement, or;
2. Try to add another layer of CF blanket and finish with a thinner layer of render or vermiculite cement?

I don’t wish to do a loose sand/perlite/vermiculite fill and enclose the barrel.

TIA!

[AndreasP]

Nino,
Do you have any insulation below the oven floor?
IF not, you may be loosing quite a bit of hear there as well.

I used 2 inches of ceramic fiber blanket and 2 inches of a 10:1 vermiculite :Portland cement over my 2 inch thick dome. When my oven is at 900F inside i measure only about 80F outside.

From what I recall the insulation properties if a 10:1 Vermiculite mix are similar to the CF blanket.

Hope that helps.

[Nino_F]

Hi Andreas - thanks for the reply. Yes, there is CF board beneath the fire brick hearth.

I’m not sure the thickness of the CF blanket but fairly certain it was a single layer only.

Yours stays much cooler on the outside than mine!!!

[Kvanbael]

So, you would remove and redo the stucco, right? Then I would add another inch of blanket and use whatever room is left for vermicrete+finish.

[Nino_F]

So, you would remove and redo the stucco, right? Then I would add another inch of blanket and use whatever room is left for vermicrete+finish.

Yes that would be option 2 - guess I am looking for any thoughts or opinions on which would be best.

[w650gb500]

If you have sufficient insulation under your cooking surface and just worried about insulating over/around your dome, have you considered building and enclosure/doghouse? That’s how I built my oven and it retains heat overnight for baking the following day with no issues.

[Pizzarotic]

Yes that would be option 2 - guess I am looking for any thoughts or opinions on which would be best.

Removing the stucco and adding 2 additional layers of blanket then redo the stucco would be the best.
Next best would be 1 additional layer of blanket and a Vermiculite/Perlite 10:1 layer then redo stucco.
Third would be, additional blanket layer over existing stucco and another stucco outside. (Least effort)
The difference between all 3 options would be minimum.