42" Pompeii oven in Gloucester, Virginia.

[Novaslo]

Re: 42" Pompeii oven in Gloucester, Virginia.

Your doing great....you ask for advice and you take advice. Your build is going to be great.

[Novaslo]

Re: 42" Pompeii oven in Gloucester, Virginia.

I chose to use Durock boards.
I was surprise how still fragile they are. I heard crunches here and there when I first handled them so I was getting more careful with them.
I also used some cable across the frame to prevent bowing the frame.
I saw that on other pictures and I thought that was a good idea.
When I look back I think I should have left more space between the rebars and the Durock boards.

I used the same boards, what did you mean when you said you should have used more space? I haven't done my pour yet and would be interested in what you noticed.

[Yannick]

Re: 42" Pompeii oven in Gloucester, Virginia.

What I meant is that the space between the durock and the rebar is maybe 1 inch or less. When I used thicker spacer then the rebar was getting too close
To the top part of the form.
It was just a preference of mine but i ideally wanted the rebar to be centered in the slab. (Same amount or concrete above and below the rebars).
But the durock was resting on the block wall, so I lost half inch
Of space below the rebars already.
In the end I think I could have used a taller spacer between the durock and the rebar and still be ok.

[Yannick]

Re: 42" Pompeii oven in Gloucester, Virginia.

I did not get much done today. I took 10 days off to work on this project.
Today I picked up 200 firebricks, 3 bags of Heat Stop 50 and an OSB sheet.
I tried to make the invaluable tool but my first try did not work so well.
I had to cover the vcrete because of the storm today.
My truck load looks messed up after an emergency stop.
On the third picture, it's the layout that I am going to use. I found it on this site with measurement.
We will see how it goes.

[hubert_s]

Re: 42" Pompeii oven in Gloucester, Virginia.

What I meant is that the space between the durock and the rebar is maybe 1 inch or less. When I used thicker spacer then the rebar was getting too close
To the top part of the form.
It was just a preference of mine but i ideally wanted the rebar to be centered in the slab. (Same amount or concrete above and below the rebars).
But the durock was resting on the block wall, so I lost half inch
Of space below the rebars already.
In the end I think I could have used a taller spacer between the durock and the rebar and still be ok.

I think it would make sense to have the rebar closer to the bottom of the slab rather than in the center or top since the bottom is where the tensile stress will be when it is loaded in bending.

[david s]

Re: 42" Pompeii oven in Gloucester, Virginia.

Try to expose your vermicrete slab to as much sun and air movement as possible. Because around 1/3 of its volume of the mix is water, the hydration process will have left a lot of free water (more than half of it) that needs to be eliminated. Once you have covered over it that water is harder to eliminate later with fires. Check the attachment which explains this further.

[Gulf]

Re: 42" Pompeii oven in Gloucester, Virginia.

Try to expose your vermicrete slab to as much sun and air movement as possible. Because around 1/3 of its volume of the mix is water, the hydration process will have left a lot of free water (more than half of it) that needs to be eliminated. Once you have covered over it that water is harder to eliminate later with fires. Check the attachment which explains this further.

And, had you not placed the moisture barrier between the structural slab and the insulation layer: Some of that water would have soaked down into an already green supporting concrete. It would have even taken longer to drive that moisture out with later fires because it would be trying to wick (equalize) up into your vcrete .

[NCMan]

Re: 42" Pompeii oven in Gloucester, Virginia.

This thread caught my attention. I had poured my Perlcrete slab last week. I placed a vapor barrier (6 mil poly) under my hearth slab. After pouring my concrete hearth slab, I left it covered for two weeks. After uncovering, I then placed yet another layer of poly on the slab (under my Perlcrete). This, I learned from folks on here, acts as both a vapor barrier and as an uncoupling membrane. After pouring the Perlcrete, I then covered it w/poly and cardboard for a couple of days, to help the curing process of the Portland Cement in the mix. After a few days, I completely uncovered it all to let the "drying" process begin,as it needs proper time to now dry out. I will leave it alone for at least a few more days to dry out as much as possible. Having the uncoupling membrane/poly in between all the layers, I now fully understand why it should be done this way. If we get any rain in the meantime, I plan to cover it back up until it passes, as to not get it saturated again and will do my best to keep it dry during the build. I figure the less water that needs to be driven out during the drying fires, the better. I don't look at the fires as "curing" fires. Curing, to me, is a totally different process and is not what is done w/the fires at all. I call them drying fires.

[Yannick]

Re: 42" Pompeii oven in Gloucester, Virginia.

Here is an update on my project:
I cut the floor and placed it on the stand.
After dry testing the fit of first layer I finally affixed it.
I did not get to do more because of the weather.
Now I have more questions.
What is better to have the 21" tall dome or the shorter dome?
The 21" seems easier since there is no adjustment needed on the IT.
What do you suggest?

[ATK406]

Re: 42" Pompeii oven in Gloucester, Virginia.

Since you are starting your dome on a full soldier course - 6 1/2" above the hearth floor, it looks like you will have to adjust your IT anyway or taper the bricks on your second course (maybe your 3rd and 4th courses too) to avoid a large mortar joint between your soldier and second course - assuming you want to maintain your 21" interior height (which I would recommend).

To put it another way the sum of the angles created between each course must add up to 90 degrees when you reach the top of the dome. At this point, the angle formed between your hearth floor and your IT at the top of your first course (soldier) is approximately 17 degrees. That equates to a mortar joint of about 1 3/8" between the top of your soldier brick and second course (assuming the face of your 2nd course is layed perpendicular to your IT). That's a pretty big gap.

There are a multitude of solutions - tapering the bricks on your next few courses is one option adjusting your IT as you go is another.

Sorry, I'm mot trying to come off as a "Smart Alec" (or worse) just want to make sure you have a strategy to achieve the dome shape/height that you desire.

Regards,
AT

[Yannick]

Re: 42" Pompeii oven in Gloucester, Virginia.

I really wish the manual had some actual measurements about the dome, the floor and everything else besides the oven stand.
I didn't realized that using the full brick would change the shape of the roof.
On the picture attached, the green line is 21" from center. (where the dome should be if I did not use the full brick.
So this is what I came up with. Let me know if that's alright.
The first 3 bricks will be tapered.
First brick 15 degres (1 1/4" tall inside oven)
second brick about 10 degres (1 3/4" tall inside oven)
third brick 15 degres (1 1/4" tall inside oven)
After that the gap on the outside for the rest of the bricks is about 3/8" (5 degres between bricks)
So is that a good way to build the dome?

[ATK406]

Re: 42" Pompeii oven in Gloucester, Virginia.

That will work as long as you leave a gap for your mortar between the 1st, 2nd, 3rd and fourth courses. In other words you don't need to taper those bricks quite so much. That's still a lot of brick cutting. Get used to it...there's a lot more to come. One other option...as much as it hurts, you could start over again and bevel the top of your soldiers...or skip them altogether. It shouldn't be too hard to salvage them and you haven't gotten that far anyway.

If you are relying on the FB plans, have you thought about how you will manage the dome to inner arch transition? That is one of the sketchier sections of the plan.- but hey, the had to leave some things to discover for yourself.

[ATK406]

Re: 42" Pompeii oven in Gloucester, Virginia.

If you haven't gotten that far in your head, spend some more time reading about some of the builds on this forum and you can learn from other's mistakes and successes. Something I wish I had done. I didn't join the forum until I was already closing in.

[UtahBeehiver]

Re: 42" Pompeii oven in Gloucester, Virginia.

Run a strip of duct tape along the gap between the soldier and the floor during your dome build. This will keep any surplus mortar from dropping down in the gap. This will keep the gap free and the floor expansion from potentially cracking the dome.

[Yannick]

Re: 42" Pompeii oven in Gloucester, Virginia.

I will try to continue the way it is by tapering the bricks.