Retaining Wall Musings - Pizza Oven Project - February 2025

The pizza oven patio project continues to be a work-in-progress with a number of details that we need to figure out/solve-for before too much time passes, so we can begin the project when the weather breaks.

Back in January, I posted this 'notebook' post - where I ran through a number of decisions/items that need to be sorted and came out with these three lists.

First, the list of 'elements' or component-projects inside the larger project:

1. The floor
2. A retaining wall
3. Stairs from patio
4. Roof Structure (with piers)
5. Prep Counter/bar-top
6. Utilities
7. Landscaping
8. Oven doghouse, landing and veneer

Second, I put together a series of 'prep-work decisions' that need to be made:

1. Figure out utilities. Primarily electric. where they go, how they get there. in
2. Figure out 'level' for the floor and base of retaining wall. That requires decision on material. 2 depths - sunken prep area.
3. Wall details: placement, material, size, height, length, stairs, drainage and even stairs. This determines the floorplan.
4. Lay out floorplan. Size of roof. size of bar, etc. Landing size/depth. storage. utilties, stairs
5. Concrete foundation locations. For posts of roof structure and prep counter (and tie in utilities)
6. Determine oven doghouse and landing and veneer.

And, finally...I put together this project plan:

1. Excavation - for wall and floor and concrete footings and piers
2. Run electrical
3. Prep - gravel base for wall, floor and footings and piers. Install sonotubes.
4. Build Wall and stairs
5. Install Roof Structure and doghouse
6. Install bar counter/prep counter and landing
7. Install final floor.

Recently, I mused about trying (or thinking about) a 'floating, ground-level deck' instead of a paver patio (#1 on the first list).  I'll keep thinking about pavers (vs deck) and try to come to a conclusion soon. 

I also started to work on the middle list this month by calculating the 'level' for the floor and the drop of the retaining wall.  This post shows the string + level method that revealed we have a 26" drop between the grade of the 'upper' (existing) patio and the lower, pizza oven slab grade.  

26" means that the retaining wall is *just* a little bit taller than 26".  I figure the wall will have a 'cap' on it and in order to be effective, the first course needs to be buried (at least) half-way into the ground.  

In order to figure out the *actual height* of the wall, we have to decide on the block type.  That height also impacts the engineering required for the wall construction.  There are a couple types of wall:  free-standing, gravity and reinforced walls.  

Free-standing are stacked walls - straight up-and-down.  Gravity walls are pitched backwards a little bit.  And re-inforced walls that require some engineering.

Menards has this handy chart below that shows some of the recommended height limits for using a gravity wall design.  Clifton blocks are 40" wall height limits.    

Our wall is 26" tall.

But, remember that we need to bury 'at least' half a course under grade.  Let's look at those Clifton blocks.   In their design gallery, they have this project that used Clifton blocks:

Those are 8" tall.  And they're using a 3.5" cap.  26" wall plus 4" of 'below' grade' = 30" wall.  

If we're using a 3.5" cap, that means we are likely going to have to build a four-course wall (8x4 = 32") plus a 3.5" cap = 35.5" total height.  Bury the entire full first course and we'll end up with *close to* a 26" height wall.  

I don't know how long the wall will be (that's something else I need to figure out), but I used 18' as a 'guess' in the wall-builder tool at Menards.  Here's what the system spit out:

This wall - which likely needs additional gravel, comes in around $1300 for the rest of the materials.  

I'll need to figure out the true length of the wall and what shape it needs - straight line vs. square vs. curved/wavy walls.   Right now, I'm thinking of an L-shape wall that extends out into the backyard.