42" Pompeii construction in Adelaide

[P3 Stoaker]

G'day All,
I've had a think about the way forward, and to be honest whilst I remained concerned about moving forward on the advice of 1 person, the endless experience on this Forum is something I've found super helpful to the point that I've decided to go ahead with a more traditional build. Thanks Russell, as you say if I mix it up things could get complicated, I'm not a gambler and thanks JRPizza, if it's not broken why try and fix it and there is less risk going traditional.
So I'll probably stay with the 42.5 Inch. I've read many posts and a few have recommended for the 42, a 12" tall by 19" wide opening, however this around 55%. Lots of posts say around 62-63% or a little either side. Would appreciate thoughts as to whether 55% is within reason ??
Regards

[GreenViews]

Greg, Seems like a good question to me. The FB guild v 2.0 gives the following guidance which calculates to 60% for high vault and 71% for low vault 42". That is within a few percentage of the 63-68% widely recommended. Mine is a 36" low build so their recommended door is 69%. Personally, I was tweaking my build to go 9.75" door and 15" dome for a 65% ratio, which is closer to the 63%. I'd love to hear others weigh in as I have no real world results yet. p.s. just posted video of my second course going in!

[P3 Stoaker]

G'day All,
Greenviews, sounds like you are progressing well. The 9.75 inch opening is lower than I was initially thinking, by around 1". And your dome is almost 5" lower. Certainly makes the IT tool design interesting but by the sounds of it you have that sorted. Out of interest why are you going low dome?
I've decided to stay safe and keep to more traditional dimentions, although I am considering a slighly lower entry, at around 55%. I'll be more comfortable moving forward with those dimentions if I can lure the thoughts from a few of the wise and experienced members, hence my question in the previous post. I hope to get some feedback regarding that.
My oven is going just outside a pergola which is also under construction and includes an open fire. The framing was completed today and the heater is in place awaiting some panelling and render. So has kept me busy awaiting info regarding the pizza oven design. I'll post a few pics tomorrow.
Regards

[GreenViews]

Yeah, FB guide recommends 12.5" opening height and 21" high dome for your 42" round high vault style. I also hope others can verify that is good in their experience. My reason for low dome: I simply read somewhere that it made better Pizza. I later read opinions that the difference is minimal and low dome uses more wood, but I'm committed now.

[P3 Stoaker]

G'day All,
Greenviews I have included a few pictures of our pergola area progress, pizza oven just outside the end and open fire along the side, which will be panelled up. In hindsight I probably would have had the oven under cover but the area was planned before that thought and extending the pergola past 6m (20feet) was a lot bigger task structurally.
Can anyone tell me, can we see posts where the newest page displays first? I can't find an option for that, will save selecting through every page of one's own build every time and I'm sure there must be a way given some members have 20 or 30 pages ??
Build questions, should the first dome course be mortared to the oven floor bricks?
I'm never sure whether to repeat a question swamped by several posts after asking a question if not answered?? To be answered readers would need to track back several posts, should I just repeat questions in that case?
On that subject I was chasing thoughts as discussed in post #46, any thoughts/comments would be greatly appreciated.
Regards

[GreenViews]

Hey Greg, I love your new space. Going to be beautiful!

Been doing some thinking on your question about door height and no further answers from others. I think JR and Utah probably feel they already answered. I went back and looked JR gave example of his latest build and I went back to his build thread there to review. His Pompeii (high dome) was 39" build, so presumably 19.5" dome height and he used a 12.25" door, so 62.8%. JR also shared other research saying 63% is the key. Utah then shared 63 to 65% door height for high dome and slightly different for low dome. I'm guessing they feel they have given what they can from their knowledge and experience. Might have to look for posts from others who used a different ratio to see their experience???

First dome course: I was instructed twice to not mortar the first dome course, but to lay it down with a 1:1 sand:fireclay mix. They say it needs to be free to move slightly.

Specific questions: I do see others starting a new thread in the appropriate place in the forum if they do not find their question answered after searching the forum. That might be a way for others to see your question who are not following your build.

Order of posts: Wow, good question! I've been either typing the number of last page in at the top of a thread or going to the bottom and selecting the last page. I just looked and also didn't find this option.

[GreenViews]

Just found the option for viewing conversation by latest activity first... in the User settings page select Latest activity... I then noticed this is a toggle on the top left of all "conversations" so you can switch back and forth easily regardless of your default.

[JRPizza]

So, did you all have a look at the Quebec oven document? The authors were doing a little "reverse engineering" looking at door to dome ratio. They noticed that some ovens had supplemental "holes" in the oven which they speculated were added because the draw was not proper. I attached a screen shot of their graph. They use a ratio of 1-(door/dome) for some reason, so a 63% ratio is 37 on the graph. We used to say at work that very small deviations from spec are usually not harmful, but we rarely knew at what deviation the performance would be seriously effected. That is where my knowledge of opening height is For what it is worth, the concept of a performance drop as a function of deviation from nominal is called a Taguchi loss function (for those that like to nerd out https://en.wikipedia.org/wiki/Taguchi_loss_function)

[P3 Stoaker]

G'day All, thanks for the feedback.
Greenviews, thanks for the reply, I appreciate your comments, and yes acknowledge regarding questions.
JRPizza, Thanks for the reply. I'm going down the more traditional high dome dimensions, full even arc dome but with a slightly lower entry. Slow progress with lots going on but I'll get there.

Regards
Greg

[GreenViews]

Hey Greg,

It looks to me like you did your homework on the door arch meeting the dome. I would also look at slightly lower elevations in the arch to be sure they don't move back from your dome. This would depend on the shape of your door arch and I don't remember if you said what your plan was. I did a segmental arch which worked well with the shape of my dome. Many people do a rounded or semi-circle I believe.

Related to this and your question of the template. If you are doing a rounded arch: start on a piece of plywood and mark your door sides and the very top of your door. Next mark the centerline of your door and measure down from the door height mark: measure half the width of your door and make a mark at that point. Then you use a something to make a semi-circle from that centerpoint you marked from one of the walls to the top of your door then continue in the circle to the other wall. Above where this semi-circle meets the wall is your template cutout for the top of the door and bottom of your arch, below where the semi-circle meets the wall will be straight wall to the floor of your oven.

If you are doing a segmented arch, the process would be similar, but you would choose the center of your arch according to how flat or rounded you want the top of your door to be. I personally had it roughly figured out then waited to finish my template until I went up 3 bricks, then calculated the center of my segmental arch based on the radius needed to meet the actual height of my wall to the desired height of my doorway.

Can't help with the other questions, although I was told a regular tile thickness is sufficient. I actually had other used tiles at the ready, then seen pic (if I remember correct) of your mosaic tiles, then went to a Habitat Restore (used building supplies supporting Habitat for Humanity) and bought some of the same like I saw cause I though.. lots of room for the water to run off and out. If water accumulates higher than that, I'd imagine I'd have greater problems that need resolving, but I have no real world experience. Looks like your plans are coming alone quite well. Can't wait to see it take shape! Cheers Tom

[P3 Stoaker]

G'day All, Some progress today. Made another arch template and worked out the taper arch cut position on TDC (photo no 1). No actual brick in the photo as I couldn't hold the brick and take the photo. I think the IT and lines drawn give the idea. At the moment I have a caster at the bottom of the IT but I believe it is quite accurate as it sits in the photo. I have a fork bolt and I'll improve the IT before I get into dome works. Given TDC sort of governs or effects the position of the lowest arch brick I was keen to get this finalised so I could cut the floor tiles, (photo 4 and 6). The tiles are 12" square by 2" thick and the size made the whole cut process quite easy, as best as I can tell anyway not having built an oven. The floor is 1" larger than the dome all around just to spread the load. Possibly not needed but easy to do so went for it. Photo 5 jumped in there, an open fireplace adjacent the pizza oven. The blue board will be rendered ( I think called strucco in the US) to match the pizza dome render.
I previously posted in 'tips' but for those that didn't see it and are thinking of using Mosaic Tiles under Casil board, DO NOT LET THEM GET WET. The glue holding the netting dissolves quite quickly when wet, meaning they can only then be moved as individual tiles, not good !!!! Less than half got wet and luckily I have a lot of extra sheets and managed to salvage some of the wet one's by getting them on sheet metal. I think the glue has reset but also to the adjacent sheet as well.
Has anyone heard of or used waterproof perlite? I'm wondering if it dries quicker. I'm only using the perlite to build up/fill the area's beside my dome but would be handy if it dried quick. The description says "LiteFill Perlite is treated in a solution to give each particle a waterproof coating".
Kind Regards
Greg

[JRPizza]

It looks like you have your arch location well dialed in. It will be fun to watch your build progress!

[P3 Stoaker]

G'day All,
Progress a little slow, eldest son's 18th with family last weekend and his mates for bonfire next weekend, yes, two 18th's, thanks Covid!!
So I recently filled the side area's of the Pizza oven base with perlite concrete, mainly as it's lighter and easier to work with compared to normal concrete. Mosaic tiles on the bottom and 3 by 1 inch layers of casil board on top. (photo's 3-7) I hope to start the dome soon. Will appreciate thoughts on a few things;
1 I've read plenty, lay the first dome course on the oven floor on fireclay. Can/should that be thick at the back in order to start the dome arch? In line with the IT?
2 I'm looking at using a tapered half brick for the dome. Initially for the lower dome courses they can be lay'd offset as per photo 2 and when the curve begins to sharpen they can be lay'd as per photo 1. What do you think? Has anyone seen or used something similar?
Kind Regards

[UtahBeehiver]

1. You only need fire clay/sand under firebrick if one the CaSi board needs leveling or two the fire bricks have various thickness and also need leveling. If everything is flat, no need.
2.Yes and Yes,

[P3 Stoaker]

G'day All,
Thanks Russell. I hope to start the dome soon, which will be dome on top of the floor brick method. The Casil is level and the floor bricks quite even so I hope not to need fire clay under floor bricks. If I do I recall 50/50 fireclay and sand.
What I am wondering about is I have read many times, ' do not mortar the first dome course down, use fireclay if necessary'. In the end mortar between the bricks will obviously be required which has me thinking about this first course, do we sit the first course up at the back, properly aligned by the IT tool, (mortar or fireclay would be required) or should it be laid flat on the Casil without mortar, except of course mortar between the bricks will be required.
Clearly, I don't have this bit sorted, any assistance/comments will be greatly appreciated.
Photo below for info, shows the overall level surface, perlite surrounding the Casil board.
Regards