Hillside Homes: Costs and Considerations of Building on a Steep Slope or Lot

Hillside building is gaining steam around the world as custom home builders prioritize preserving the surrounding natural landscape. While pouring a level foundation and then constructing a home on a steep slope is intimidating for most American homeowners, the practice has been popular for decades in other countries. Naturally hilly and verdant nations like New Zealand, Ireland and Mexico boast dozens of stunning modern homes built into hillsides and cliffs. Though building on a steep slope or into the side of a hill can be challenging, there are actually a number of safety, design and cost benefits to doing so. Learn more about the costs and considerations to keep in mind when building on a steep slope or into a hillside below.  

3 Gorgeous Hillside Homes Around the World to Inspire Your Custom Build

#1 House on a Slope by Gian Salis in Grenzach-Wyhlen, Germany

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First on our list of hillside homes around the world is this terraced build -- designed by Gian Salis and constructed in the hills of the Rhine Valley. Jessica Mairs explains Salis’ intentions for the build and his approach to hillside architecture in her article “Gian Salis' House on a Slope steps down a hillside in the Rhine Valley” for Dezeen. Mairs writes that this “glazed house built from thick concrete slabs was designed...to follow the slope of a plant-covered hill in Germany's Rhine Valley.” Appropriately named “House on a Slope,” this German home “sits on a hillside that was once used as a vineyard but is now overgrown with mature trees, shrubs and grasses.”

Terraced designs are common when building on steep lots set into hillsides because they reduce the amount of excavating needed to construct the home. They also offer a special take on indoor-outdoor living, notes Mairs as she quotes the architect Gian Salis. Speaking about the design of House on a Slope, Salis explains that “‘the varying projections of the storey ceilings form terraces and protruding roofs, creating specific exterior spaces as counterparts to each interior space.’" Building a terraced home not only fosters a rewarding connection between the constructed property and its surroundings but it also maximizes living space and minimizes cost and damage to the land.

#2 Modern Cliffhanger Residence by Jon and Gill Flewers in Malvern Hills, England

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Chronicled in Season 15 of the British television series Grand Designs, this stunning curved-facade home boasts a terraced backyard garden and visually powerful entryway. Though built in Malvern Hills on a plot purchased site-unseen, this home was actually inspired by the countryside of New Zealand and the ways in which homes are situated within rockfaces and rolling hillsides. Homeowners Jon and Gill Flewers bought the steep plot because of its resemblance to their property in New Zealand, thinking that British builders would be able to construct their ambitious home much in the same way. Though the couple ran into a number of complications along the way -- mostly due to lack of proper preparation -- they ended up with a gorgeous home that meshes well with the surrounding landscape and blew away everyone involved. In her article “Grand Designs UK: Kiwi 'cliffhanger' house has a layout that surprises” for Stuff.co.nz, Colleen Hawkes notes that “Grand Designs host, architect Kevin McCloud says it [was] one of the steepest [building locations] he had ever seen” and that “builder after builder turn them down.”

The pair ended up conducting much of the design and construction themselves, opting for an upside-down plan that placed the sleeping quarters upstairs to capitalize on panoramic views. Though they exceeded their budget, the home was completed to enormous visual effect. Impressed with the results, host Kevin McCloud described the home as “house is described by Grand Designs UK host Kevin McCloud as “positively Antipodean.” Jon and Gill Flewers proved that with enough preparation, research and ingenuity, one can safely and successfully build on a home on even the steepest slope. Though the Flewers designed this home by themselves, involving a design-build firm would significantly speed up and smooth out the process.

#3 The Till House in Navidad, Chile by WMR Arquitectos

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A vacation home hidden amongst trees along the coast of Navidad, Chile, Till House is a contemporary beach home designed by Chilean architects WMR Arquitectos. In her article “Chilean Beach House Offers Complete Privacy for Distraction-Free Vacationing” for My Modern Met, Sara Barnes details the build and the firm that designed it. Cut into the cliff, this home “boasts roof access, a wrap-around porch, and sliding doors that allow you to see all of the outdoors even while you're in bed.”  Timber framing alternates with massive panes of glass, allowing the entire house to bathe in light without feeling washed out. Though the home is made almost exclusively of floor-to-ceiling windows, its strategic location high in the cliffs prevents drivers-by from peering in from the road, offering its owners perfect privacy.

Rather than shy away from the challenges of building in such a remote and rocky area of the Chilean coastline, WMR Arquitectos embraced the home’s surroundings. “Till House by WMR Arquitectos in El Arco, Chile” from ArchitectureArtDesigns.com explains the firm’s approach. The article notes that the home is “simple but elegant and is strictly bound to the cliffs that are blown by the wind.” WMR designed the home to “integrate and merge with the natural environment, the construction is mostly wooden, built on one level and stretched lengthwise.” WMR Arquitectos aligned views from the single level home with the horizon, blending sky and ocean. The result is an organic masterpiece at one with nature.

Answering Your FAQs About Building on a Steep Slope

#1 Can I Build a Hillside Home in High Rainfall Areas?

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A home built on steeply sloping land can be just as stable as other homes if the soil beneath it is well-packed and the house is properly protected. In his article “Should I buy a home on a steep hillside?” for MySeattleHomeSearch.com, Conor MacEvilly writes that many homes built on steep slopes are constructed responsibly with sufficient drainage and stable foundations. However, the safety and security of a hillside home is not purely determined by the quality of that home’s construction and maintenance. MacEvilly writes that in rainy areas with poorly packed soil hillside homes beneath other properties could be at risk. This is because “wet, dense soils on the uphill side of the home’s foundation can exert a lot of force on the uphill foundation walls of the home.” In fact, writes in the article “Spotting the slippery slope: What to watch out for when buying a hillside home” for The LA Times, “‘rain is the biggest cause of problems for hillside homes…[because] wet and dry cycles lead to heaving, shrinking of the soil and related building movement.’” Thankfully, even this heightened risk of mudslides can be mitigated by adding a retaining wall to your hillside home.

Building on a Slope is Safer in Arid Regions without Earthquake Risk

Homes situated in drier climates are less likely to face erosion issues, making hillside houses a better fit for arid regions. Perhaps the best way to ensure your hillside home is protected from disaster is to design and build a custom house from scratch. This is because older homes -- even luxury residences built in coveted areas like Malibu and Topanga Canyon -- “are especially prone to issues.” Quoting Dave Grover of Grover Geology, Carren Jao writes that “‘back in the ’50s and ’60s, homes didn’t have the strict codes we have today.’” Building into the side of a cliff or on an otherwise steep slope did not require “elaborate geologic studies to make sure you were building retaining walls or debris collection devices that would protect the house.” As such, designing your custom hillside home from foundation to finishings with a reputable firm can ensure a safer, longer-lasting space for you and your family.

#2 Are Hillside Homes at Greater Risk of Earthquake Damage?

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The Design Everest post “Hillside Home Projects and Their Challenges” notes that “earthquakes pose a considerable threat to hillside homes, particularly to those built on a downslope - extending away from the hill with the entry floor at the top.” As one might imagine, older homes are at greater risk of damage from earthquakes because they were frequently built on stilts that are not able to “resist the rotational force” exerted by earthquakes. Modern homes equipped with “primary and secondary sets of anchors and struts that attach each floor assembly of a house to the closest foundation segment” rather than relying on stilts are much more likely to effectively resist earthquake damage. Once again, the best thing homeowners can do to protect their homes against earthquake, flood, mudslide and landslide damage is to work with a practiced architect and builder to create a fully up-to-date build that closely follows or exceeds all safety recommendations.

#3 Is Home Insurance More Expensive for Hillside Properties?

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As one might expect, hillside homes built on steep slopes can be more vulnerable to mudslides and flooding if poorly protected. This vulnerability might increase home insurance premiums, writes Connie Thompson in her article “Live on or near a hillside in the soggy Northwest? Check your homeowners insurance” for Komo News. Insurance companies might require higher monthly payments if you live in an area prone to erosion -- such as along the coast or in a region with high annual rainfall -- but they might not cover earth movement damage at all. When considering constructing your home on a steep slope, Thompson recommends shying away from newly populated areas. She writes that “hills where new clearing and development are taking place...might increase the chance of erosion or slide conditions around your property.” This is because altering the landscape by removing natural barriers like trees, root systems and boulders can make homes more vulnerable to mudslides, landslides and flooding. Because of the risks detailed above, quality earthquake insurance might also be difficult to secure for a reasonable monthly cost.

#4 Is Building on a Steep Slope More Costly than Building on a Flat Lot?

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The cost of building on a steep slope rises and falls significantly based on the location of the lot, the grade of the slope, the type of soil or rock and the amount of land that must be excavated to lay the foundation and then construct the home. Location of the lot will impact cost if that location is fairly remote or severely limits crane and truck access to the site. The home’s position on the hill could also impact cost, as it might require more complex and expensive drainage systems if located downslope of other homes. Grade of the slope, quality of the land and design of the house itself can also affect cost to build. Depending on the design of the home -- specifically its size and shape --, extensive excavation might be required. The type of soil can make excavation more time-exhaustive, more dangerous and thus more expensive. For instance, soil densely packed with hard rock like granite can be difficult to break up, requiring large machinery and highly trained operators. Creating a stepped or terraced home can reduce the amount of excavation required and can actually offer the house additional support from the hill’s natural landscape.

#5 Can I Add a Backyard to my Hillside Home?

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The answer to this question is a two-parter. Backyards are actually fairly common in hillside homes built on steeply sloped lots. However, they are often constructed in slightly less conventional ways than typical backyards. Hillside developments often feature either sloped or terraced gardens in the back of the home, but paved backyards can be added if the foundation’s concrete slab is extended past the built footprint of the house. Flat backyards built into the hillside will often be protected by a retaining wall. To create a beautiful, fully functional backyard behind your hillside home, we recommend following advice from the Better Homes & Gardens editorial team in their article “Planting on a Slope.”

Terraced Retaining Walls Offer Safety and Usable Outdoor Space

The BH&G editors suggest hiring a landscape designer to install “several low walls with level terraces,” interspersing paved patios with native gardens. This type of “sloped backyard design creates an inviting patio, a great place to sit and survey the rest of your garden.” In addition to the retaining walls, native plants will also protect the ground from erosion because they are better adapted to the site’s specific soil profile. Alternatively, one can create a multi-level deck with wood harvested from the region for your home on a sloped lot.

4 Steps to Safely and Efficiently Build Your Dream Home on a Steep Slope

#1 Work with a Design-Build Firm

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In their article “How to Build on a Sloping Site” for HomeBuilding.co.uk, Mark Brinkley and Allan Corfield write that “steeper sloping sites can be a challenge...during the construction phase [because] most sloping sites don’t have a convenient flat area large enough to use as a contractor’s compound.” As such, “workers either have to build something or continually work on a slope, which can be dangerous and takes up additional time.” Choosing an inexperienced contractor “who’s only worked on flat, open sites...could be a massive mistake.” Thankfully, hiring a design-build firm like Element Homes ensures that only experienced, properly equipped construction teams are chosen for complex builds.

In our recent article “Benefits of Working with a Design-Build Firm from Start to Finish,” we explained that “working with a design-build firm ensures project delivery on time and within budget” -- even on complicated projects like those constructed on steep slope hillsides. Working under a single contract prevents delays and miscommunications, practically eliminates the chance of legal disputes and makes sure an appropriate, close-knit team is assembled for your project.

#2 Minimize Excavation

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In her article “How to Artfully Build a House on a Hillside” for Houzz, Jen Dalley emphasizes the importance of minimizing cut and fill to reduce costs and protect your timeline. She writes that once you have designed your home with a design-build firm, “it’s time to find the best location that minimizes excavation.” The design-build firm hired for your project will likely commission a survey to “accurately identify the amount earth removed (cut) and earth added (fill).” By investigating “how to minimize excavation,” you will save money and time while protecting the natural landscape of your hill. Limiting excavation will also better stabilize the lot, reducing the chance of erosion due to over-development.

#3 Prioritize Proper Drainage

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In the Natural Resources Conservation Science Wyoming brief “Drainage Tips for Hillside Home Owners,” the USDA recommends homeowners, designers and builders ensure roofs are “properly fitted with gutters and downspouts that will release water onto a non-erodible surface such as a paved driveway.” The USDA also suggests adding a “concrete curb, a compacted earth berm, or other similar structures on the outside edge of a driveway or building pad [to] direct runoff away from sensitive slopes to an area where it can be released safely.” Proper grading, lined ditches, established drainage for retaining walls and runoff diversions can all protect your hillside home from flooding and erosion. Proper grading “promotes good drainage” by preventing “water from pooling around foundations, flooding basements or below grade structural components, and concentrating water into destructive volumes.”

#4 Consider Unconventional Designs

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As mentioned above in our segment about Grand Designs guests Jon and Gill Flewers, building a home into the side of a hill, cliff or mountain may necessitate ingenuity and flexibility to be successful. Inverting traditional layouts -- e.g. designing a backyard on the top tier or a kitchen on an upper floor -- can improve the functionality and attractiveness of a hillside home. An unusual design could even add to the resale value of your home. Beckie Strum recently wrote in her article “Los Angeles ‘Upside Down’ House Sells for $22.5 Million” for Mansion Global about an unconventional house designed by LA architect Noah Walker in 2015.

Encased in glass, this unusual home capitalizes on the surrounding landscape’s natural beauty. Strum noted that Noah Walker “flipped the script on the standard layout in order to integrate the home more seamlessly into its environment.” This resulted in a “living room, kitchen and other public spaces...located on the top floor, while the bedrooms are buried into the hillside on the level below.” The 8,000 square foot home boasts “a green roof ‘of edible herbs’...six bedrooms and 10 bathrooms...a serene open-air courtyard at its core and numerous balconies and terraces on both levels to take in the rolling hills beyond.”

Tech-Savvy Design-Build Firm Element Homes Helps Protect Hillside Houses

Custom home design-build firm Element Homes employs state of the art technology and industry-leading professionals to ensure each home they create is optimally suited to the landscape and to the safety of its inhabitants. As a design-build firm, Element Homes not only designs your home but also the ideal team for your specific project. This team works together seamlessly to take care of every specific need posed by the homeowner. From architectural planning through the entire construction, Element works under a single contract to deliver all the benefits associated with working with a design-build firm from start to finish. Homeowners are promised peace of mind through custom project dashboards frequently updated by the company, allowing clients to view their project from anywhere in the world.

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