Do I need to Parge the dome?

[EricU]

I finished the dome portion over the weeked and have a few questions.

I remember seeing some of the domes that were parged on the outside, I plan to cover the dome with an enclosure that will have a roof and will be filling the void with pearlite for insulation:

1. Do I need to parge the outside of the dome?

If I do need to parge the dome, with what material:

1. Mortar mix?
2. Pearlcrete?

[EricU]

Re: Do I need to Parge the dome?

And if it is going to rain this weekend, do I need to tarp the dome?

[Tscarborough]

Re: Do I need to Parge the dome?

You should certainly tarp it. As for parging, that is up to you, but insulation is not optional. It looks extremely nice, BTW.

[EricU]

Re: Do I need to Parge the dome?

Do I need to parge it?

Is there a reason to parge the outside of a dome?

Usually parging is for strengthening the back of a wall or some other structure.

[SCChris]

Re: Do I need to Parge the dome?

I don't know that parging really adds significant strength to the dome so then it's about asthectics and additional mass. What you need at this point is to insulate and then to weather proof things as best you can. I put a house around my dome for 2 reasons, to maximize insulation and to create a weather tight cover for the oven and its insulation. Are you finishing with a dome or house? Oops I see that you'll be finishing with a house. I'd advise using the ceramic blankets to wrap your dome before filling things up with perlite. They seem to cost a bunch, but they will pay you back in no time.

Have you started your curing yet? I ran a quartz shoplight in the oven with a loose brick door with just enough opening to allow some air movement. I did this for several days to saturate the oven to the mid 100s before starting my very long low slow burns. Even these low mid 100 temps will start to push the water out and days of this easy no brain curing will make a big difference in the end. Definately cover the oven to keep any rain off, a shade structure would be ideal to still allow air movement around the oven. Don't wrap the oven in a tarp, unless you need to keep the rain off, you need this air movement to dry the structure.



Chris

PS Eric very nice workmanship!!!

PSS Concrete's strenght is in compression. The thin skin of parging doesn't utilize this attribute.

[EricU]

Re: Do I need to Parge the dome?

...I'd advise using the ceramic blankets to wrap your dome before filling things up with perlite. They seem to cost a bunch, but they will pay you back in no time.

Oh yes, I will be building an enclosure around the dome, brick, cobble, 6x6 redwood posts, 3x6 redwood roof joists with lighting & speakers.

• Why the blankets? And how many at $75 a pop?

Have you started your curing yet? I ran a quartz shop light in the oven...

I just installed the keystone last Saturday and was going to let it dry in the sun for a week. Well we haven't had a lot of sun here in Napa this week and we have a chance of rain which means we probably will get sprinkled on.

I wouldn't say that I have started the curing process

• Is there a link to a thread that explains the process?

But I did throw some paper in there last night and light it! Not much, just a little. I will throw a shop light in there tonight and try that.

[SCChris]

Re: Do I need to Parge the dome?

Here is a link for the curing area. http://www.fornobravo.com/forum/f16/...uring-767.html

As for the blanket, I know the $75 is a bunch. I think the R-Value of the blanket is higher than you'll get with just Perlite. I went with Stonewool bats at about half to a third of the cost of the blankets but the blankets seem to be much easier to form around the dome structure. These bats are available at places like Supply line or industrial insulation houses and are used for fireplace backing and sound deadening insulating wall bats.

I know that Stonewool blankets are available in some places, back east?, Canada?, but I didn't find it in my area. The R-Value of the Stonewool is about the same as the ceramic blankets and the working temp range of Stonewool is fine for a WFO. The down side is that the bats, boards is what they're defined as, is not nearly as good as the blankets for wrapping the dome.

Outside of the Stonewool I used Fiberglass bats for the structure corners and finally filled the house with Vermiculite. I'm happy with the insulating results I'm having, by using 2 inches of rigid CaSi board insulation under the oven floor and the same material as a door I loose about 100F per day after the the first 24 hours. The first 24 hour temp drops are higher and I believe these seem to be about continued charging, continued heat storage and evening out of the heat, in the oven structure.

You're going to see that the substructure will dry over the first 15 to 20 fireings and less heat will be transfered out of the concrete support hearth, the R-Value of the concrete will rise as it drys out. Your oven will react quicker to heat as it breaks in.

Related to this, as you cure, and the oven drys out, you're going to find that it's easy to excede the goal temperatures for your curing schedual. Be attentive and don't let the heat run away from the temps that you want. Slow and steady is your mantra for curing!

Chris

[EricU]

Re: Do I need to Parge the dome?

Here is a link for the curing area. http://www.fornobravo.com/forum/f16/...uring-767.html
...as you cure, and the oven drys out, you're going to find that it's easy to excede the goal temperatures for your curing schedual. Be attentive and don't let the heat run away from the temps that you want. Slow and steady is your mantra for curing!

This may sound like a dumb question but;

• Where do I take the temp readings from?
• Inside at the back of the dome?
• Inside at the top of the dome?
• Outside while the dome is still exposed?

[SCChris]

Re: Do I need to Parge the dome?

I ran the temps from both the inside soldier and inside top of dome and the top of the inner arch areas. I think what you'd like to see is some consistency of temps. This said your readings from the inside top of the dome is going to be higher than the soldiers by a pretty good margin, sorry I don't really remember if its 50 or what this difference was for me. I also ran outside temps to try to get a feel for how saturated the dome was.


I also didn't insulate until I had the interior temps up over 200F. My reasoning was that I wanted air movement around the exterior of the dome to clear the water vapor and felt that insulation might just contain this vapor more than I wanted.

These burns were 14 to 20 hours long and were ment to get the water moving and keep it moving.


Chris