How to Build a Terraced Slope in the Backyard

Measure the hill to determine its rise and the number of terraces you will have to build at a given height. In general, steeper hills should have taller terraces. However, the actual terrace heights are up to the gardener. For example, a hill with a 10-foot rise could have five 2-foot terraces or ten 1-foot terraces. The fewer terraces the hill has, the longer each terrace can be.

Measure the run of the hill to determine how long each terrace should be. For example, consider a hill that will have five 2-foot-tall terraces. If the hill has a run of 20 feet, each terrace should be 4 feet long.

Measure the width of the slope to determine how long to cut lumber for the terrace support walls.

Cut the timber so that each terrace will have one front support wall and two side pieces. Shallow terraces can have single pieces of lumber for their walls, and tall terraces might require a few pieces of lumber stacked on top of each other to build the walls. Cut enough lumber so that the bottom of each wall can be buried at a depth equal to 1/2 its thickness. Some of the lumber will be buried in the ground to stabilize the terraces. Alternatively, purchase precut lumber with the right dimensions from a home supply store.

Buy thin metal pipes or spikes long enough to stick through holes in the terrace walls and into the ground. For 1-foot terraces, buy 18-inch spikes. For tall terraces with multiple layers of wood, you can buy spikes long enough to stake just the first layer of wood, and then attach additional layers of wood together with other spikes or bolts.

Dig a level trench at the base of the slope. Make the trench deep enough to fit about 1/2 the height of a timber support wall in the trench underground, while leaving enough of the wall above ground to make the terrace the desired height. Dig the trench wide enough to fit a timber support wall into it.

Dig two trenches into the slope along the sides of the terrace, making sure the bottoms of the side trenches are level with the bottom of the front trench.

Place one of the precut timber pieces in the front trench, and pack soil around it to secure it in place.

Place timber pieces in the side trenches along the edges of the terrace, and pack soil around them.

Drill vertical holes through the timber all the way down to the ground.

Hammer metal spikes or pipes through the holes in the walls to secure the terrace support walls into the ground.

Add additional pieces of timber on top of the base pieces, if needed to build the walls up to the desired terrace height. Short terraces often need only a single piece of wood, but tall terraces usually need multiple pieces.

Drill holes through additional timber pieces, and put spikes or pipes through the holes to connect them to each other and hold them in place.

Move soil from the back of the terrace to the front of the terrace to make it level.

Repeat steps 6 through 14 to build terraces up the slope until you reach the top of the slope.