Building a raised patio is a great solution if the ground level of your backyard doesn’t align with the grade of your house. 

If you simply wish to step straight out of your house onto the patio without installing and using steps, a raised patio is quite a feasible project that can help you utilize most of the space you have.

Once a level area is achieved, you can comfortably set up patio furniture without worrying about it sliding or toppling due to uneven ground surface.

To ensure a raised patio is installed properly, follow these six steps. 

1. Planning

The first step in planning your raised patio installation is deciding on its measurements, including the height from ground level to the top of the patio. 

The measured height depends on the slope of the yard and is a crucial detail in the process of installing a raised patio. In case the patio is taller than the final grade, you’ll have to consider your area’s building code.

The next step involves deciding which products to use in building the patio. It’s a good idea to refer to manufacturer specifications and use the patio retaining wall products in building the raised patio. 

Consulting the specifications can also help you understand if it’s necessary to install a geogrid on the retaining walls, place a drainage pipe, and keep a particular space between the retaining wall and the patio structure to compensate for any surcharge.

Once you have decided on the retaining wall blocks and the products (a paver or slab) for the patio, you can make a final decision on the patio dimensions. This is done by taking into account the paver or slab dimensions along with the dimensions of the retaining wall cap. 

Also, make sure you integrate a border between pavers or slabs and the retaining wall cap. You can simplify the cutting process by laying the caps as close together as possible and laying the border pavers over the pavers or slabs. Then you should mark the line where you will make the cut and drop the border pavers in their place.

2. Excavation

Firstly, you need to mark the area of excavation. You can do this by calculating the patio dimensions, and adding another minimum of 6” to each side, and then spray painting the excavation area.

It’s important to check if there are any underground obstructions in the excavation area. You can consult your local utility marker and have them check the area. This service is most often free.

The next step is deciding on the equipment you’ll be using for the excavation. You might need to rent some of the equipment and buy on-site bins for excavated soil. 

Use a rotary laser, an altimeter, or string line and level to measure the slope and learn how deep you'll need to go. This will also confirm whether you need a railing or not. If you want to avoid it, you could include a landing and incorporate steps.

3. Product Calculations

The number of pavers or slabs you’ll need for the patio will depend on the square footage of your chosen area, including the area where the retaining wall caps are. Also, make sure you subtract the square footage of the border between the patio and the caps. 

So, to calculate the square footage, multiply the linear footage of the border by its width. To calculate the caps of the retaining wall, add up the length of all the sides and divide it by the length of each unit. Keep in mind that the retaining wall itself will require a minimum of 6” underground.

To calculate how many units you will need for one layer of the retaining walls, measure the length of the patio sides and divide it by the width of the patio’s retaining walls. After that, measure the height of each retaining wall block and the height of the raised patio starting at the final grade to decide the number of layers you’ll need.

Once you have finished calculating, you will know the number of step downs, retaining wall blocks, and layers of retaining wall blocks you’ll need to order. Make sure you order an additional unit for each corner since there will be cuts.

Additional materials include base material, biaxial geogrid, geotextile fabric, perforated drainage pipe systems, and a jointing compound of your choosing. You can calculate how much of the base material you’ll need in yards by multiplying the square footage with the depth in inches and 0.0003.

4. Base Preparation for Raised Patio

This step includes compaction of the subgrade, i.e., subsoil. Clay soils are covered by a thin layer of clean stone, dusted with cement, and compacted by a ramming or a heavy reversible compactor. 

Sandy soils can be compacted using a plate or reversible compactor. Make sure you don’t over-compact to allow the water to penetrate the subsoil.

The compaction is then followed by the installation of the geotextile fabric — woven for the patio, and non-woven for the retaining walls. Geotextile fabric separates the base from the subgrade and allows for water filtration and tensile patio strength.

Once both the compaction and geotextile fabric installation are completed, the base for the retaining walls can be prepared. The base can be either open-graded or a base of Granular “A” or 3/4″ crusher fines. 

An important factor to consider at this point is how you will manage the water on the patio surface since a raised patio has a high point and a low point on the level retaining wall. There are two options you can consider:

1. Drain installation in the middle of the patio and a slight slope towards it.
2. A permeable jointing compound installation which allows the water to flow through it.

The second option requires the installation of an open-graded base with a geogrid stabilizing the base material. The open-graded base also includes the installation of the drainage system with the pipe installed behind the retaining wall of the raised patio to collect any water that comes in.

5. Building Retaining Walls

The crucial step here is ensuring that you start at the exact elevation point of the raised patio. This dictates the number and the height of the blocks, as well as the height of the caps, which usually differs from the blocks' height. 

To map out the starting line, use a string line. You will also need to install the biaxial geogrid throughout the patio to stabilize the base material and provide strength in both directions due to the raised patio structure.

After building the retaining wall, you can start installing and compacting the base material for the patio interior. When you reach the desired height, you can glue the caps using a polyurethane concrete adhesive. The remaining base material is used for the patio itself.

6. Installing the Patio

This step includes the placement of a screed layer on top of a concrete subfloor, laying, cutting, and jointing compound installation.

If you are building a raised patio against your house, don’t do it directly. This can cause pressure from the movement. Instead, purchase extra materials and install the final side to the patio retaining at least a 1/2″ gap between the house and the retaining wall.

Conclusion

A raised patio is the perfect solution for turning your sloped yard into a functional space you can use for entertaining and enjoyment. 

Thanks to its elevated level, you’ll be able to step out of your house directly onto the patio and have your morning coffee while you bask in the warm sun.