Brick Patios – Two Methods of Installation
Two Installation Methods
The Brick Industry Association will tell you that there are four installation methods available to you. In reality, there are only two that would ever be used by 99.999 percent of homeowners in America. The two that are used are the flexible base and the rigid base.
The flexible base system is a combination of crushed rock, maybe gravel and coarse sand. Guess what? You can only use mortarless brick with this system. Oooops! I used mortared brick in my "experiment" 20 years ago with my inadequate (no crushed rock!) flexible base.
The rigid base system used with paving brick employs a concrete slab beneath the paving brick. This slab can be a steel reinforced slab or one with no steel. I prefer a steel reinforced slab. Both types of brick can be used on a rigid base. Do you see why you have to make up your mind before getting out the shovels?
The Flexible System
To begin your patio you must know where you are going to finish. Does that make sense? What I mean is that you need to establish a finish height and then work backwards. This allows you to establish the top of the dirt upon which you will place the first wheelbarrow of crushed rock or concrete.
A flexible base system requires a minimum of four inches of crushed rock as a base material. Some interlocking brick manufacturers may suggest six inches. Once this is in place, you need to smooth it and compact it. Compaction is best achieved using a mechanical plate-type vibratory compactor. It operates much like a walk-behind lawn mower. The only difference is that you sshaakkkke a lot while operating it!
Once the gravel base is in place, you top it with 1 1/2 inches of coarse sand. The sand is not compacted just yet. You smooth it off to the exact profile and the slope you wish the final patio to be. Once this is complete, you simply set the concrete bricks onto the sand. The interlocking bricks just mesh together. Undoubtedly you will have to make cuts where the bricks round corners or intersect border bricks. Saws, cutters and chisels will accomplish all cutting tasks.
Now that we have gotten this far we can see how much dirt we had to dig. Let's see, we had six inches of gravel, 1 1/2 inches of sand and a brick that is 2 3/8 inch. That adds up to just about 10 inches! That's a lot of digging.
So you don't like to dig? Well, maybe the rigid base system is the way to go for you. It requires 20 percent less digging if you use the standard clay paving brick. However, the placement of the concrete, brick and mortar between the brick requires more labor and skill.
To further complicate things, the look is often different. Using a clay paving brick with a rigid base, you can create a patio that has the look of a brick wall. You actually have mortar joints between each brick. The mortar can be colored or standard gray. The choice can be complicated, no doubt!
The Rigid Base System
This system is what I have used. My current house has thousands of clay paving bricks laid in a thin (1/2 inch) layer of Portland cement mortar. A 1/2 inch mortar joint is between each brick as well. The look is stunning. The deep tones of red clay brick match my country Victorian home quite well. Of course, Kathy picked the colors. I can't match socks much less house colors.
To begin my rigid base system I installed a four inch thick steel reinforced concrete slab. I installed the concrete on top of two inches of pea gravel. This gravel allows water to escape from beneath the slab. Water under concrete in the wintertime can cause serious frost heaving!
The concrete was poured at 4,000 PSI which allows it to resist damage from cold Cincinnati winters. The 1/2 inch steel bars are placed on two foot centers in both directions. The steel is placed above the dirt so that it ends up right in the middle of the concrete slab.
Once again, you need to figure out your total system thickness to determine how deep you must dig. In my case, I needed to excavate eight inches of soil. Don't forget to slope your patio! Make sure that water drains away from your house. A slight slope of 1/8 inch every two feet is undetectable as you walk across the patio.