Using Splits in 42" Pompeii

[cnicholson]

Alrighty...

I think I'm almost there..got the foundation and blocks up and I'm trying to think 1 step ahead. Here my question, and I have searched the forum and read all the relavent posts I could but would still like some expert opinions... I have a source to get firebrick splits at .25 each...my question is will building 100% of the oven with these work? It seems as though you could lay the floor with a double layer, perpendicular to each other...mortaring in between layers seems to be the question. Also in building the domw it would stand to reason (and others have suggested) that using splits would obviously take more brick, and create additional mortar joints, but would reduce the size of the joints so maybe would only use a little (25-35%) more mortar...I realize the advantage of using the full size bricks with build time, etc.. but .25 each is pretty tempting...Thanks in advance!

[cnicholson]

Re: Using Splits in 42" Pompeii

In looking at the pompeii tutorial once again I had an idea...it suggests embedding a layer of splits in the insulation layer under the standard floor for more mass if you plan on baking bread...I'm thinking this method could be used with using splits for the floor and would net a 2 1/2" floor...this method would also allow me to use a thinner, more standard material for the landing and bring it flush with the cooking floor? Not sure if there is any benefit for the latter...just throwing it out there,,thanks again..

[cnicholson]

Re: Using Splits in 42" Pompeii

OK...another observation...the guide is showing the insulating concrete being poured flush to the edge of the structural pad..is this necessary? I would think you would get a flatter surface and more desirable starting point to build the walls if the insulating layer was kept in the thickness of the enclosure walls?

[GianniFocaccia]

Re: Using Splits in 42" Pompeii

Per the FB plans, the stand, dome, floor thickness and enclosure dimensions are general guidelines. Take the time to understand the ratios and spacing involved and once done, you are free to modify them to fit your materials, construction skillset and personal style.

There are those who will reject using splits because of the extra mortaring work involved, but there is no argument for $.25 bricks. Are they Pacific Clay by chance? If it were me, I would use them in a heartbeat for two reasons: I think an oven made of splits employing modern materials and tools could create a wonderful 'old world' look that can only be found in ancient builds. Also, beveling a 1" brick could be accomplished by eyeballing and make for a really quick build.

No, your insulating layer does not need to go to the perimeter of the support slab. Look through a number of builds here and you'll see that virtually everyone keeps their insulation just under the dome walls. Regarding your floor, given your 1"-thick firebricks, it appears you have ultimate flexibility in building to just the depth you need. My oven has a 2.5"-thick firebrick sub-floor topped by a 3cm (1.25"-thick soapstone floor. Whatever your cooking preferences, build the floor depth accordingly and I'm sure you'll figure out the landing part.
John

[apagios]

Re: Using Splits in 42" Pompeii

regarding your last question, I am pretty sure the plans have pics of other examples where the insulating pad only goes under the oven and not to the full area of the structural slab.

If not then I have definitely seen pics on this forum of pwoplw who only insulated under the oven (and walls, you don't want dome bricks sitting on un-insulated structural concrete).

As far as splits go, very tempting price!

I personally have gone with the theory that I'd rather spend money now and build it well then go cheap on something I am only building once. I would have a similar concern with the splits having many more joints. From a basic systems analysis point of view (sorry I'm an engineer ) you ideally want to build anything with the fewest options for failure. Increasing the number of mortared joints buy only using splits I think would make it much more likely to have crack form, either right away or during the lifetime of your oven.

I am certainly not an expert, and still finishing my first oven, so there are certainly much more experienced masons here that can chime in. I have learned a TON by searching around this forum, and following links when people reference their own build threads.

[cnicholson]

Re: Using Splits in 42" Pompeii

Many thanks for the replies...I did see some other threads with the insulation just under the dome but I thought I would ask that specific question too..

Gianni..I agree that the old world look would be "off the hook" as they say nowadays...and it's also a good point at eyeballing tapers rather than having to make cardboard/paper template for the tapers on full size brick..and yep..pacific clay

apagios...I agree with the notion of less pieces offers less chance for failure, especially when moving pieces are concerned...but in this case my theory held on the fact that natural materials WILL move no matter what and I think in the original design that microscopic cracks develop in ALL the joints. Giving the dome more joints allow for potentially better disbursement of the cracks...if that theory is totally false my other thought is that although you are adding twice as many joints, if they are all mortared correctly, there is no more chance that one will fail over the other. On the other hand you are certainly increasing your odds with twice as many joints...

I think I'm going with splits! Another question to put out there...if I'm using splits does anyone see any advantage to one method over the other for the soldier course?

[GianniFocaccia]

Re: Using Splits in 42" Pompeii

I think I'm going with splits! Another question to put out there...if I'm using splits does anyone see any advantage to one method over the other for the soldier course?

Like many other builders, I would skip the soldier course altogether. Given the circumference of the dome's first courses, you're gonna get wicked angles that require significant volumes of mortar to fill 1" brick gaps. Also, bricks layed horizontally benefit from gravity in creating the bond between courses. Besides, you can simulate a vertical-sided soldier course quite easily. Looking back, I'm pleased as punch I replaced my soldier course and went horizontal.

Here's a pic of what I'm talking about. Inherent with a 1" brick is the ability to create a wonderfully smooth curve to the inside profile of the dome with little work involved.
John

[cnicholson]

Re: Using Splits in 42" Pompeii

That pic motivates me to get moving!! Your points are well taken...a rare case where gravity is actually a friend...just so I'm understanding correctly just cut the splits in half like normal and start going up with them? I was planning on using an indispensible tool type product to do the dome but I think in using splits it may not be necessary? Just lick em and stick em... is that what you were getting at before with the "eyeballing"? Thanks again.

[Mike D]

Re: Using Splits in 42" Pompeii

I used a plywood board as a guide on the inside to help keep the curve consistent. I think it would be way too hard to just eye ball it.

Mike

[GianniFocaccia]

Re: Using Splits in 42" Pompeii

Also, beveling a 1" brick could be accomplished by eyeballing

Beveling refers to sloping the inward-facing vertical edges, or shoulders of a brick to allow it to align with its neighbor as the inside dome profile progresses upward/inward. The bevel angle increases as the bricks become more vertical. During the course of building my dome, I learned to eyeball the cut needed to have the angle end up parallel to the adjacent brick. I think this would be easier to do with a 1"-thick brick.

I agree with MikeD. You would have to be really good (or experienced) to eyeball the curvature of the dome. I used a plywood template but if you can make an indispensable tool, go for it.

so I'm understanding correctly just cut the splits in half like normal and start going up with them?

Depends on how much time you have and how much mortar you want to go through. If you just cut the bricks in half you end up with a large outside mortar gap. If you angle the bricks to maintain a uniform mortar gap from inside out (see pic), you need less mortar, but it takes more time and patience.

John

[cnicholson]

Re: Using Splits in 42" Pompeii

So in reality if I cut the bricks in half first and then started tapering them as I went up, the dome would actually be getting thinner by the amount of the taper as I went up? Would that effect the performance of the oven at all? It would seem as though the top would heat up/lose heat a bit faster than the lower part of the oven? I'm not really interested in using a whole lot of mortar.

I guess I could factor in the taper as I went up to keep the mortar joints consistent (as thin as possible I am assuming thinnest would be best)...Also my thought was to make an indispensable tool with a turn buckle and about 2" of adjustment room for the length. Assuming I used 1/4-20 threads and started at a 21" length (42" diameter), if I turn the turn buckle a certain amount of full turns on each course wouldn't that give me a consistent curve and also a finish height some where in the 19" range?

Now that I think about it I would have to figure out how many rows of bricks I would need to get to my 19" (give or take) and see if I could get a turn buckle/rod thread to where a full turn (or 2) per row would finish me out at 19"? Of course assuming that 19" would be where I wanted to be at full height on a 42" oven? Or am I just WAY over thinking this whole thing?

Also, I'm trying to figure how many split bricks I'll need...should I just double the 200 to 400? I'm actually thinking about picking up 500 as the yard is a bit away...only problem is if I have 100 bricks left over I'll have to find a use for them...maybe a smoker? Yeah...that would be a problem... Thanks again.

[cnicholson]

Re: Using Splits in 42" Pompeii

Alrighty then...I went to the supplier and attempted to pick up the bricks...unfortunately after waiting around 45 minutes I HAD to leave due to a previous appointment I could not be late for...so I may try again but I do have a question, I noticed another thread addressing this as well but didn't really see a concise answer, the face of the bricks seemed extremely rough and grainy...not sure if that is why they were in the seconds pile or not but...

I am assuming the first few times you hit the surface with a peel (or equivalent) the aggregate is going to dislodge and then get swept out, which would most likely occur doing the curing, but if someone can answer from experience I would appreciate it..thanks!

[GianniFocaccia]

Re: Using Splits in 42" Pompeii

the dome would actually be getting thinner by the amount of the taper as I went up

Huh? If the depth (from inside out) of the brick is 4 1/2", this will remain constant in each course throughout the dome. Tapering causes the inward faces of the bricks to get shorter, meaning you will need more of them to cover the same area as a 2 1/2" tall brick.

if I turn the turn buckle a certain amount of full turns on each course wouldn't that give me a consistent curve and also a finish height some where in the 19" range?

Your indispensable tool design is fine. I would cut out a dome template and use it to start (and periodically check) each course to keep the inward angle accurate. Your template can be cut to end up at any final dome height you wish.

I would have to figure out how many rows of bricks I would need to get to my 19" (give or take)

Get a copy (free) of Sketchup and mock up your entire oven, espcially the inner arch transition and you will save lot of time and mortar. See pic.

the face of the bricks seemed extremely rough and grainy

If you're referring to the wide side of the brick as the face, this is a non-issue for dome bricks since they are buttered with mortar and are never seen. If you plan on using the wide face for the floor, I wouldn't. Spend the $100 and purchase 2 1/2"-thick standard firebricks that are smooth. This is your cooking surface and it should be as smooth and homogeneous as possible.

John

[cnicholson]

Re: Using Splits in 42" Pompeii

Thank you John...I am now wrapping my head around the tapering of the brick as you "draw the purse strings" on the dome if you will...and the significant advantage of using splits at that point...

On the floor... I looked at another brickyard this afternoon and I have to say that the non-seconds do not looks much better actually... I have a pizza stone from Crate and Barrel in my oven (electric oven that is) and I was hoping for a finish like that..is it possible to wet polish the finished floor with diamond pads to get a better finish on it? I think I'm going to look at the FB floor material as well...

I have sketch up but admittedly haven't used it for much... your illustration speaks volumes about laying it out on paper first...thanks again for all the direction and insight!!!

[cnicholson]

Re: Using Splits in 42" Pompeii

Ok...if anyone is interested in what 500 splits look like here you go...It seems like a LOT of bricks but hey...if it was easy everyone would have a pizza oven in their backyard...that brings up a question to everyone out there..I have a friend in Sacramento who wants an oven but just can't do the work..they were quoted $9000 for an oven (not too sure how much detail was involved) but if anyone is, or knows anyone who is, interested in doing an oven for hire let me know...

As far as the "seconds" go...as far as me, or the brick yard guys could tell, the reason they were in the seconds yard is for the discoloration on some of the bricks. It looks like the clay didn't get mixed too thouroughly in those spots...about 5-10% of the bricks had some degree of discoloration..the one shown is about the worst one...

So if anyone is interested, Pacific Clay in Lake Elsinore has about 2500 left at .25 each...ask for Mike in sales.. (951) 674-2131...

One caveat...don't go on a Monday if your short on time and ideally call ahead and he can get them ready for you...