Living on a sloped lot proves troublesome any time you attempt a landscaping or outdoor building project. Fortunately, building a patio on a hill or slope does not need to be a professionals-only task. You can build your own hilltop or hillside patio by preparing a proper base and form before actual construction begins. You will need a level base with proper drainage, regardless of the building materials you intend to use for the patio.
Excavate the patio site in the desired width and length. Begin at the lowest point of the sloped site and excavate to a total depth of 6 inches in this location. In the higher portions of the patio site, you will remove additional soil and dig deeper into the ground to create a site level with the shallow side of the patio.
Survey the bed of the excavated site with a 2-foot or 4-foot level. Remove heaped areas of soil to provide a level surface on which to build the patio.
Compact the soil at the site's bed using a mechanical or manual soil compactor. Depending on the size of the patio, you may use a manual compactor by thrusting the device against the ground to compact the soil or simply roll a larger, mechanical compactor over the area to compress the soil.
Add a 3-inch layer of gravel to the site to provide base material for the patio. Level and compact this layer using a 2-inch by 4-inch board to grade the surface of the gravel, a level to check the site and the compaction tool used in Step 3 to compact the gravel layer.
Build a retaining wall around the shallow edges of the patio site. Stack brick or stone against the interior edges of the site, one layer at time, until you create a wall measuring the same height as the excavated edge at the deepest point of the patio site. You may use mortar to install the retaining wall, if desired.
Fill the area inside the patio site with fill material such as gravel. Leave 3 to 6 inches at the top of the site to provide room to place paving bricks or stones or to pour a concrete slab. Proceed to set the patio paving materials in place on the prepared base.
Depending on the size of your patio, use either a spade or backhoe to make short work of the excavation process. Leave a larger depth at the top of the retaining walls to provide a thick concrete slab patio. Slope the paving materials 1 inch for every 6 feet of the patio's width or length to promote proper drainage of water from the finished patio surface.