Mortaring In First Course - DIY Pizza Oven Construction - May 2024

Last I posted about my backyard DIY pizza oven construction project, I was showing the foundation slab after I had stripped the forms.  The pour went well - thanks to the MudMixer.  Now that the reinforced slab was done, I can move on to building the stand.  That stand is made out of 8x8x16 cinder blocks.  If you go back and look in the archives, you'll see that I went back-and-forth about the dimensions of the slab and stand and after a bunch of thinking/tinker'ing, I ended up deciding on these dimensions:

Slab: 72" wide x 80" deep.

Stand: 4 blocks wide x 4.5 blocks deep - 62.5" wide x 70.312" deep.

Hearth: Same as stand.

Oven: 39" interior, 51" exterior side-to-side x 64" front-to-back.

That's the slab that I poured: 72" wide (6 feet) by 80" deep (6 feet, 8 inches).  And, so I could go about building the stand with four blocks wide and four-and-a-half blocks deep.  

Setting these blocks square is important and I had to play around a bunch with getting it right.  I borrowed a snap chalk line and went about trying to figure out how to make a perfect 90-degree angle to set the first corner.  I have that large surface drain that sits on the slab and the dimensions of the block mean that I was going to have to cut-it-close there.  So....I decided to start with that corner; that way I knew the drain would 'fit' inside the stand.  I had a framing square, some string, a tape measure and a couple of levels and did my to cut a 90.  Thanks to high-school math, Mr. Pythagoras of Samos (is he a 'mister'?) and the ole' 3-4-5 right triangle test, I was able to snap out some lines with a high degree of confidence they were square.  

Then, I went around and laid out my block.  I filled all the spots - even where no block will go due to openings - to make sure things were spaced properly.   Here, below, is the first go at the edges of the stand:

Making sure to hit that line with the outside edge of the block:

Then, I removed the blocks where the openings are going to be - starting with the back two:

I then slept on it for a night.  

When I woke up the next morning, I futz'd with the blocks a little more and then dove in:  mixing up my first batch of Type S mortar in a bucket.  

Starting with the 'highest' part of the stand (I used a level to figure this out), I began to set the bottom course of block with the Type S Mortar.  I used a level and a mallet to work my way around the stand and eventually mortared all of the blocks in.  I used the angle iron that I had on hand to ensure the gaps were straight.  It took me a little over an hour and three small batches of mortar to get them all locked in.  See below for that first course:

Level and square.  A success.  

For my first masonry project, I'm pretty happy with how it came out.  I watered in the mortar for the rest of the day to keep it from drying too fast and allow it to cure.  

A couple of days later - just to see how it would look (and to determine if I ACTUALLY had enough blocks on hand), I decided to dry stack the second course.  See below for a few photos showing the stand going vertical.

Turns out, I need to return some of the cinder blocks and buy a few others.  A pallet of block comes with two types of blocks:  those that have clean corners and those with little 'nubs' on both ends.  The clean corner ones are for just that: corners.  The 'nubs' blocks are for in the middle of the runs.  I have too many 'nubs' blocks and not enough corners to do another course.  

Once I get those last few blocks, what comes next is dry stacking (and ensuring their straight) the next two full-block courses, one half-block course and then the bond-beam course.  Right now, I'm thinking this will be four-and-a-half blocks tall, but before I lock that in, I need to sort out my oven floor insulation.  

Why?  Because the height of the oven floor is important - don't want it too tall/too short.  I'm aiming for about 45" from the grade.

Once I get the insulation situation sorted, I can move on to finishing the stand.  

After setting them in place, I'll need to add rebar down every-other-core, bend it across the bond beam blocks and then fill those cores (every-other-one) to lock the stand in-place.  When that is done, it is time to move on to the suspended hearth.