Creating usable space with sloped properties can be challenging but not impossible. This extra layer of complexity can add more interest and make the spaces more dynamic while maximizing accessibility throughout the property. Working with the existing slopes of a property instead of against them will help you find better solutions that keep the entire design cohesive and expand your project budget.
Patios and Decks
Although they feel completely level, most patios are installed with a 2% slope to help with drainage. Paired with stairs and retaining walls, patios can be used to create terraced spaces on slopes that can be used for fire pit areas, entertaining, or dining. Deck platforms can be built on slopes as well to create a level surface for seating. Between the two, decks are typically going to have a higher cost than a patio space due to materials, labor, and permitting (but of course, there are always exceptions to this). As a slope gets steeper, it’s going to need more interventions (such as more or taller retaining walls, steps, etc) which will increase cost. Creating multiple levels can decrease wall heights, cut and fill needs, and make the transitions more gradual.
Pathways
Pathways connect spaces together and help with slope stabilization and allow for easier access throughout a property. On a gentle slope, a compacted gravel or paver path can work nicely without stairs. A moderate slope may feel uneasy to walk on so it’s best to include steps in your path to accommodate the change in elevation. If you have a steeper slope, switchbacks will help create safer paths that are easier to walk on. If you’re installing a paver path, you’ll typically use matching block steps. You can pair these types (and other concrete or man-made steps) with block retaining walls to help hold the slope on either side of the steps. Compacted gravel paths pair well with stone risers and boulders can be used to flank steps and stabilize the slope.
Boulders
While boulders are great to place near paths and steps for slope stabilization, they can also be used individually or in groupings to prevent soil erosion in key places. They can often be a less expensive alternative to retaining walls and work well in both modern and more rustic landscapes.
Water Features
Blending aesthetics and functionality, water features are a great option for dealing with slopes. Large elevation changes allow for dramatic water falls while gentler slopes can accommodate bubbling streams and smaller water weirs that end in a pool at the bottom of a slope. Water features can really make a garden come alive and if you’re in a mild climate, can be left on through the entire year creating a focal point in the winter garden.
Retaining Walls
This is often one of the first elements that come to mind when dealing with a slope. They can add structure and definition to a hillside and are able to transform an unusable steep slope into a functional and aesthetically pleasing space. Retaining walls can be built from rock, concrete, blocks, or steel creating a wide array of choices to suit any garden style. Retaining walls work well for terracing as you can create level areas for seating, playing, or planting between walls. Retaining walls at the edges of patios can also double as seat walls. Walls can also be made into raised planters for edible plants or cut flowers. It’s important to check with your jurisdiction before building any retaining walls. Typically walls that are under 4’ tall from the original grade won’t require extra planning but over that height may trigger permits or the need for engineering. You’ll also want to plan for proper drainage around any retaining walls to prevent erosion, cracks, sagging, or collapsing. Water will naturally collect at the bottom of a slope so having a plan for how to divert that water is crucial.
Lawn
Lawn on slopes can be tricky to establish and maintain, but not impossible. Slopes under 5% will be ideal especially for lawn games, etc. As you get closer to 10%, the lawn will still be maintainable but may not be as easy to use or play on. Just like patios, it’s good to have at least a 2-3% slope away from any house foundations so water drains away and doesn’t pool or cause other drainage issues. Sod can be used on steeper slopes where seeds may wash away too quickly before it establishes. Hydroseed is another option for installing lawn on slopes as the grass seed is mixed in with a mulch that helps it stick to the soil. Consider mower access and ease of mowing before choosing to place lawn on a moderate to steep slope. If mowing isn’t an option but you want a lawn-like appearance on a hill, a no-mow grass or other lawn alternative are options worth considering.
Planting Areas
Plants are integral to stabilizing slopes. Roots help anchor hillsides and absorb water as it drains down which slows erosion. Plants that develop deep root systems and grow quickly will be best for hillsides. Many native plants are great for slopes because they are already used to the climate and attract wildlife and pollinators. Spreading groundcovers help choke out weeds while quickly forming a mat that secures soil in place. Any planting areas, especially right at the start, benefit from the application of mulch as it helps retain moisture, protects roots, and suppresses weeds which all cuts down on maintenance needs. Sloped planting areas should be irrigated with a drip system as it is more efficient at getting the water where it needs to go (the roots) instead of draining down the hillside. Any type of overhead watering (sprays, rotors, or hand watering) can cause runoff and create erosion hazards.
A Note About Steep Slopes (anything over 30%)
In most jurisdictions, these types of slopes are not allowed to be developed unless there are special circumstances noted on the site. A permit is almost always needed to do any work on this steep of a slope and may require a critical area site plan, geotechnical report, and/or extra engineering. It’s important that no trees or other vegetation is removed from these kinds of slopes without explicit approval from the city or county so as not to cause any erosion or landslide hazards.
While slopes can take a lot of planning, the right combination of elements can turn an unusable area into a beautiful garden with spaces for the whole family to enjoy for years to come. If you’ve been considering a landscape renovation but have challenging slopes that have held you back, we would love to help! You can fill out our new client questionnaire here if you’re ready to get started.
