At the end of the last update, the milestone reached was
closing the dome. What remained was the entry which includes two support
columns that get filled with concrete, two arches, a way to connect the two arches,
and a way to connect the vent to a chimney anchoring plate I bought. Well, I
bought the whole chimney system already and that is one of several reasons I
can’t park in the garage. The chimney system includes the already mentioned
anchor plate, a 5 foot piece of double walled stainless steel chimney pipe, a
two piece flashing system for the roof, a chimney cap and spark arrestor. I’m
pretty sure the spark arrestor will be overkill, but it isn’t the first thing
I’ve way over designed for the oven.
I started by laying out and dry stacking the columns. The
goal was to leave a 1.5 inch “reveal” around the arched opening to the dome.
The idea is that you can make an oven door that slides into the dome arch and
seals on the 1.5 inch reveal. I also picked up some carbon fiber gasket –
similar to the stuff the helps seal a wood stove door- to create a small air
gap between the dome and the arch. The gap, which may or may not actually be
necessary, is supposed to prevent heat flow from the dome brick to the entry.
There are two camps on the gap issue: those who have one thinks it works great,
those who don’t have one consider them useless. I fall in the middle. It
probably isn’t useless but it probably doesn’t matter too much. With or without
it, the oven will still work.
I ran a bead of fireplace glue around the dome arch and
pressed the gasket material into it. The glue goes on with a caulk gun and it
seemed like there were some water pockets in the tube. It threatened to make
quite a mess, but I dodged that bullet. Here’s the installed gasket.
The two columns press up against the gasket leaving a tiny
air gap. I dry staked the columns to get a feel for how they would be
installed. Here’s the big problem. The chimney pipe is 8 inches in diameter. The
anchor plate is a 12”x12” square. The bricks are 9 inches long, 2.5 inches
thick and 4.5 inches wide. I wanted the gap between the two arches to be about
8 inches to catch all the smoke to send it up through the chimney and away from
my face. So if there are two arches with an 8 inch space between them, and each
arch is 2.5 inches thick, that’s 13 inches and the bricks are only 9 inches
long. Plus I’ve got to bolt/screw this anchor plate on somehow.
My plan was to make the arches 8 inches apart, connect them
with a 9 inch long brick with a half inch notched at each end and make the
anchor plate fit where I wanted it. It hasn’t happened yet but there will be
some cutting of the anchor plate.
After a long day going back and forth about how actually
assemble the entry, I just went at it. And put it together. I built most of
each column (which has a piece of rebar glued into the slab below because of
design overkill), built the rear arch, then finished the columns and assembled
the front arch. When I finished, if was after 8 and I was working under lights.
Then next afternoon, I went to take out the arch forms and
touch up the mortar if needed. I broke the front arch. Into 3 pieces. The
cursing was loud and plentiful. Thanksgiving was coming, there was house
cleaning, shopping
and a long list of
stuff to do. The oven went on hold.
This last Thursday, I took a day off to work on the oven. As
it turns out, the rebuild of the front arch came out nicer than the original.
Dry stack the outer arch do-over
Outer arch set
Once the arch was set I laid out my chimney anchoring system. I’d have the
bolts go through a brick leaving at least an inch – I don’t want to risk
splitting a brick with the bolt. To make that work, I had to make
semi-circle-ish cuts in each brick. I clamped to bricks together and used
trusty Ron the Wet Saw to cut the same shape in the two bricks. By varying the
height of the say and pushing the bricks back and forth I made cuts that
eventually worked.
Side Story: one of my neighbors had a contractor that was
doing some work in their yard as I, dressed in brick dust covered clothes,
dragged Ron the Wet Saw out of the garage. Their foreman came over and asked if
I was good with “that thing.” I told him that I got by, but I wouldn’t say I
was good with it. Then I showed him the oven and we talked a little. I guess if
you have a contractor’s saw (because really, what kind of idiot would buy a saw
this big to decorate their garage?), people think you are a contractor.
Back to the vent. With the cuts made, the anchor plat fit nicely
but the original holes for bolts were not going to work. The plate is 12 inches
wide and I’ve only got 9 inches to work with. I picked spots and drilled holes
in the anchor plates where I wanted them to be. Once they were drilled I put
the pricks and anchor plate together and marked where the holes needed to be in
the bricks. A masonry bit went through the pricks pretty easily. Using
stainless steel bolts, washers and nuts it all fit together and was pretty
strong.
Bricks for connecting the anchor plate
The notched ends to a little angle grinding so they met the
curve of the arches well but everything centered and mortared in level. Once it
was set, I un-bolted the anchor plate so I could work on closing the gap
between the two bricks. The pieces I used are pretty small but I think they will
work well. They just need to prevent smoke from sneaking out. After that, one
more notched brick on each side of the anchor plate and a final brick at the
end of each arch to seal it up. After work on Friday, I put a little bit on
insulation scraps inside the column in case there was any heat transfer across
the gap and then filled them with concrete.
Bricks connecting the two arches
Concrete filled column
The oven construction part of the project is done. On to
curing.
Done. You can see the 1.5 inch "reveal" left by the vent
Curing is a misleading term. Everything in the oven is
already “cured,” meaning hardened and at design strength. This is more slowly
driving excess waster out of the oven. Steam takes up more volume than liquid
water so heating that liquid quickly into steam could produce many cracks. To
give credit where credit is due, this is an abridged explanation based on a
post written by Stonecutter on the pizza forum. It’s honestly the best
explanation I’ve read in years of reading through sites.
My driving extra water out plan is to have several small
fires without the insulation. By small, I mean not heating anything about 300
degrees and getting to that 300 degrees slowly. On Sunday, December 4 2016, I
lit a fire in the oven. I started with just brown paper bags from Trader Joe’s
and slowly worked up small chips of wood and eventually got to small pieces of
kindling. I was so focused on building the oven, I completely neglected to
stock up on some wood. I’ll need to fix that soon. For now, a bag of firewood
from Stewart’s did the trick. Over the course of about 90 minutes I burned one
log out of my bag o’ wood that I kept splitting into tiny pieces by hitting a
hatchet through the log with a hammer. It was fun. It was thrilling. I can’t
wait to do it again. Unfortunately, I think it has to wait until Friday. This
week is pretty booked up.
As I was making note of December 4, 2016 as a pizza
milestone for me it seemed very familiar. And then I remember it: December 3,
2015 was the day that Jay of OG Woodfired in Buffalo, graciously invited me
onto his food truck and
I made my first wood fired oven pizza.
I have to come
up with something cool to do next year on December 5
th.
