2017- 36" pompeii oven construction in Sac California.

[UtahBeehiver]

I really respect David's opinion, so you have a couple different schools of thought. I may have mis-spoken regarding the rectangular base to a round chimney to meaning that square chimney is not as effective as a round chimney. Here is a clip that I based my comments on from the US's fireplace manufacturer society.

"Round flue pipes vent a lot better than square flue pipes because the products of combustion rifle or spiral up the round pipe. Often, a square edge clay chimney liner is not even fully used because the gases will still spiral up the pipe as much as they possibly can"

[jas0ny]

In other words I can make my brick opening a tad bit smaller than my flue?

Another question is Lane my first row on the dumb do you guys normally taper the bricks so they have less "V" gap and less mortor to use?

[deejayoh]

I tapered mine. Are you planning to taper them for the rest of the oven? You might as well start now if you are.

[RandyJ]

If you are using home brew then that is exactly how I would go. If you are using store bought high heat mortar then you need to keep your gaps to 1/8" or less or you can have cracks from shrinkage. I started off trying to angle and bevel my bricks and quickly decided it was not worth all the extra effort. And went back to square sided bricks. I do recommend you bevel the sides of the bricks as the rows get higher so they fit together better. If I ever do another oven then this will be my plan of action. Don't worry about how much mortar you are going to use it will not matter as one bag of lime, Portland cement, and fire clay is more than enough. You might need a few bags of sand though. I would recommend that you get the finest sand you can find. Mine was like sugar all screened and kiln dried. It was from quickcreet.

Randy

[jas0ny]

I tapered mine. Are you planning to taper them for the rest of the oven? You might as well start now if you are.

Yes I will start to taper them, will start now, thanks for your input deejay, randy, Utah!

[UtahBeehiver]

I have to second Randy's thought process. I am one who wanted very tight and close joints and built my oven as such. I had lots of time and it was done to my perfectionist criteria. But is it better, probably not and it I were to build another oven I would only focus on the inside joint of the oven only and let mortar be my friend on the outside of the build. I do advocate that the internal joints be as tight as possible, including bevels and tapers to reduce the inverted "V" but you don't have to do the whole side of the brick. Only I know how tight the side joints are and they are buried under several inches of insulation.

[RandyJ]

Thanks Utah. Here is my view. If you are doing the build because you want to see how exact you can make your cuts and the build is your hobby then go ahead and taper and bevel your bricks. This is much more work and will add weeks or months maybe even years to the build process. Square sided bricks with a bevel to get rid of the gaps or inverted triangles gives the same result with much less work or calculations. So if you want to cook instead of building then just do the bevels, and you will still buy the same amount of mortar ingredients either way because they come in amounts that are grater than you can use.

Randy

[deejayoh]

This is much more work and will add weeks or months maybe even years to the build process. Square sided bricks with a bevel to get rid of the gaps or inverted triangles gives the same result with much less work or calculations.

I think that's a bit of hyperbole. I probably added less than a couple days to my build if I think about how *actual* much time it took me to cut the tapers. You can taper all the bricks on a course in less than an hour. And when you get to the top few courses - you're tapering whether you like it or not

[jas0ny]

Did the tapered cuts on everyother brick, which didnt take too long.

-My next questions is, how soon do I started making the open vent on the bricks? Wondering if there is a rule of thumb as to where the vent needs to start.
-Also I plan on creating the arch, any tips on to configure the arch? I know the tip of the arch height needs to be 11.3" (63%) of my dome height.

[UtahBeehiver]

I was using super duty firebricks so there was quite a bit of extra time and blades for me but medium duty bricks not so much. So really builder's choice.

[UtahBeehiver]

The flatter the arch the greater the lateral force will be on the side walls

[JRPizza]

Another vote for bevel only. I don't think you can avoid some exposed mortar along the horizontal joints of an oven, but if you don't taper and bevel accurately you can have brick to brick contact on your vertical joints without any exposed mortar, as long as your have some "room" for mortar away from the inner face. I always thought if you cut perfect tapers so you could have no gaps without mortar, you would end up with exposed mortar on the ID when you did use it. I was not too good at maintaining a very thin mortar joint, so maybe if you are really good at it you can taper and have super tight interior joints.

[jas0ny]

Does a 14" landing look correct?
Also do people use both bricks to cutout the vent as you see in blue on the picture? Or they just use one brick for the cutout of the vent?

[david s]

Here's my 2 cents worth to the discussion. I think too much brick cutting only results in needing more bricks and taking up a lot of extra time and in the long run not worth the extra time and expense for a result that won't be of a higher quality, in fact it may be worse. If I can quote from Daniel Rhodes in his book KILNS Design. Construction, and Operation (generally regarded throughout the world as the kiln builders bible). He says,
"In kiln building it is much better to have a loose structure than a tight one. For this reason the amateur may have a slight advantage over the professional mason, because his bricklaying is apt to be somewhat loose and not tightly locked together. I have seen kilns made by professional bricklayers which in use suffered severe cracking and swelling due to the overly tight and precise workmanship and the lack of expansion joints."
Now we're building ovens not kilns and the resulting expansion is around half that of a kiln, but the same principles apply.

[jas0ny]

In the picture below, blue box area, is that where normally the flue gallery start? right after the dome arch bricks? You an see where Ill be cutting the brick as marked with lead pencil so dont get confused for the whole brick being the depth, It starts where I have my ruler at. Or do sometimes people cut part of the dome arch brick to make this opening?