In addition to what asc2078 has mentioned ....
If you want to save the sod and reuse it elsewhere you might use a sod cutter .... either a powered cutter or the manual sod kicker.
To achieve a stable base for the patio blocks preparation is key .
It's important to ensure there are no organic materials like roots under the sub-base.
In order to reduce future settling and shifting of the blocks, it is important to excavate through the vegetation, root-zone, and soil layers and into the sub-grade.
The suggestion from asc2078 using a tiller is a good one to assist with loosing the soil for removal.
If sub-base material were simply laid over the top 3 layers, the blocks will shift soon after installation as the vegetation breaks down and leaves voids under the sub-base material. The sub-base material will then collapse into these voids and cause unwanted shifting and settling .
After you have marked out the area ..... excavate to a depth that reaches the sub-soil, clay, or bedrock below the surface....... to a depth that is deep enough for the minimum combined thickness of the :
or approximately 8" - 11" from the ground surface.
- gravel sub-base =4"+
- bedding = 2"+
- leveling = 1"+
- blocks = 1"+
If excavation must go deeper than 8"-10" to reach the sub-soil, your will need more gravel sub-base material . DO NOT use the removed sub-soil material as part of your sub-base.
A recommendation is to line the area with landscape material before the gravel sub-base is laid.
This will isolate the gravel sub-base from the soil as well prevent growth of weeds under the sub-base.
This is also helpful if you live in an area that has ground frost.
The landscape material not only prevents weeds but also will allow moisture to drain through. If there is a potential for ground frost any moisture buildup will freeze and cause heaving.
Don't use plastic since it won't allow drainage and trap the water which will cause all sorts of issues.
Once the sub-grade has been properly reached the gravel sub-base must be installed ..... thickness should be at least 4" .
The sub-base is made of gravel or limestone 3/4"-down material. The 3/4"-down refers to material that is made up of aggregate ( stone ) 3/4" in diameter and smaller all the way to stone dust. It is important to use this type of material to ensure that all the voids between the larger diameter stones will be filled by the smaller diameter material and locks it together.
Once the sub-base has been placed and spread to the required thickness, the sub-base material needs to be thoroughly compacted. Compacting this material is important to remove all the "voids" or air pockets within the material. It is recommended to use a power vibrating compactor to vibrate the material until it settles and attain a smooth solid surface.
To help in the compacting use a garden hose to soak the sub-base material ....this helps the finer material in the sub-base to fill any voids. Follow up this soaking with another round of using the vibrating compactor. You will likely find , the sub-base top surface has dropped in depth .... apply another layer of sub-base material and compact again until you have reached the correct depth.
The next step is to lay the "bedding" layer to a depth of approximately 2". The bedding layer usually consists of a construction sand .... it's cheaper than the finer leveling sand .
The bedding layer is used to fill any remaining voids in the top surface of the sub-base and to form a smoother surface for installing the blocks.
To help with creating a smooth level surface a level piece of wood could be pulled across the sand.
Follow up the leveling with compacting one time .... it does not require extensive compacting as the sub-base. It is likely that after the compacting, the bedding surface will have minor hills and valleys. Use the leveling board to sc**** off the hills and fill in the valleys.
The "leveling" layer is important ..... it's the layer that the blocks will actually rest on. If installed correctly ...... the leveling sand will ensure that the blocks are level and will not wobble. The most effective leveling sand is a very fine "play sand" although construction sand could be used as a lower cost alternative.
The leveling sand should be placed and leveled in small sections ..... not much larger in size than the block being installed. This ensures that when the level surface has been created ..... it is immediately covered with a block and not disturbed from site activities.
Place just enough sand to provide a leveling surface .... approximately 1" or less ... by creating a smooth level surface with a board or trowel and place the block on top.
DO NOT COMPACT THIS LAYER. This is very important as the leveling sand must be as loose and uncompacted as possible. By letting the block perform the compaction, the sand will be allowed to fill any minor spaces or voids between the block and the leveling sand.
Do not be surprised if a block does not end up at the exact level to the adjacent block or is slightly wobbling, and needs to be removed to repeat the process.
Set up your furniture ... sit back and enjoy.
Yikes ... got long winded again ... one of those moods.
Hopefully this makes sense and helps.