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]

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]

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]

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]

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]

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]

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]

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]

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]

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