Building On A Hill – Everything You Need To Know 

Sections on the side of a hill are relatively common here in New Zealand, and so are our beautiful coastal and countryside vistas – who wouldn’t want to make the most of our uniquely Kiwi views! Naturally, building on a hillside is a little more complex than building on the flat, but with it comes fantastic opportunities for unique and innovative design with spectacular results.

Facing the challenges of building on a slope head on is all part of the fun, but it is a good idea to gain a solid understanding of what you are getting yourself in for when considering a hill build project – let’s take a more in depth look.

What’s Different About Building On A Hill?

Hill builds differ from regular builds as they require a little extra care and attention paid to site works, stability control and structural integrity to ensure your home stays where it is supposed to (without sliding down the hill!).

For this reason, the building on a slope process will include excavation in order to create a stable platform to build on, significant retaining work to prevent soil erosion, addressing groundwater issues thoroughly, and additional bracing, reinforcing and foundational support.

4 Benefits To A House Built On Hill

Why do people build their houses on a hill if it costs more and requires extra work? The answer is simple – building on a sloping site means your home is open to unique potential. These builds provide a chance to really express your true nature and create something unique, something that, with the help of an experienced architectural build team, leads to spectacular and innovative design results! Here are the top 4 benefits of building on a slope.

  1. The Views! The number one reason people love building on a hill is to make the most of wonderful views from every window. The long term enjoyment of panoramic coastal, urban and countryside landscapes is what sets hill builds apart.
  2. Uniqueness. For many people, building your own home is more than just putting up walls and a roof – it’s an opportunity to express yourself creatively. To craft something that’s different, edgy, distinctive, unique – and beautiful!
  3. Privacy. The additional privacy that hill builds offer can be a big bonus for many people. Building on the side of a hill automatically increases privacy, noise reduction and seclusion from neighbours, passers-by and other ground-level activities.
  4. Natural Light. One of the biggest issues with building on the flat is that you often get blocked out by neighbouring properties with regards to sun, natural light and airflow. Hill builds benefit from more natural airflow, are less likely to be affected by neighbouring homes and generally have a lot more sun/light exposure.

How Do You Build on A Hill In NZ?

Here in New Zealand, we approach hill builds in various ways (depending on the site’s topography, geographical location, Geo-Tech reports and other factors), meaning foundations must be tailored to the specific terrain, ensuring stability and longevity. These are the construction methods most commonly applied when building a house on a sloped section.

    • Split Level. Where houses are designed and built across multiple levels accommodating the slope of the section (following the changes in height), these types of homes are favoured for their ability to take maximum advantage of the views and to fit more naturally with the slope of the hill.

    • Cantilevered. Where part of the house sticks out above the slope, essentially “floating” above the ground making it a striking architectural build while leaving the land underneath relatively untouched.

    • Levelled. Where part of the upper hillside is cut away and the lower half is filled up, effectively creating a flat/level area to build the house on. This method usually requires extensive use of retaining walls.

    • Raised. Where the home is built on raised supports (poles, stilts, columns, or solid walls), effectively creating a level build that doesn’t follow the slope of the ground.

8 Things To Consider When Building On A Sloping Site

What are the difficulties of building on a slope? To make the best use of your unique location when building on a hillside, you must consider the following aspects during the design process.

  1. Degree Of Incline/Gradient.  Just how steep is it? The angle of your slope or hillside and the consistency of the terrain will significantly affect what you can build, how you can build it and the length of time it will take. As a general rule, the steeper the slope, the more expensive and complicated the build will be.
  2. Additional Paperwork. All hill builds will require a geotechnical report to ensure a good understanding of what’s going on under the ground. Consent processing timeframes are also likely to be longer than usual, and in circumstances where resource consent is needed, the process can be significantly extended.
  3. Maximising Views. One of the biggest reasons why many people choose to build on a hill is the views – so making the most of them should be at the forefront of the design/build process. However, don’t forget to maximise the use of natural light in the home’s other living spaces, as there is a tendency for hill builds to focus solely on views, leaving a “dark side” to some areas.
  4. Location/Orientation. The home’s position or orientation in relation to the sun is very important for hill builds and any new build. Utilising the sun’s energy and warmth makes a huge difference to the comfort of living spaces and your electricity bill! But keep in mind overheating can be a common issue in hill builds especially if the main living areas are facing towards the west, so attention needs to be given to mitigating the worst of the heat from the sun across the summer months.
  5. Outdoor Living Spaces. Don’t forget about your outdoor living spaces, which are even more important on hill builds as you are generally some ways off the ground. Enclosed or partially enclosed outdoor living areas are great for protection from the prevailing winds, infinity swimming pools, landscaping and green spaces etc., all need to be considered during the design process as these types of areas are much harder to incorporate after completion.
  6. The Budget. Yes, building on a hill does cost more, there is no denying it. But it is easy to identify where this extra money is going and why, so this helps with managing costs. But always be aware it may end up costing even more than you think, so planning and preparation are essential.
  7. Hiring Experienced Professionals. Hiring the right team is essential for a hill build. You will need to hire an exceptional builder, architect and engineer for the design-build process and to address stability issues. The right team can make all the difference.
  8. Access. The sheer logistics of getting materials and machinery on site and moving them around can be a pretty complicated issue for many hill builds, understandably adding to the overall costs, particularly if a crane is required to lift everything onto site.

How Steep Is Too Steep To Build On?

How steep of a hillside can you build on here in NZ? Building on a variety of different sloped terrains is almost always possible; however generally speaking, the steeper the slope, the higher the costs and complexity of the build. The most manageable slope to build on will have a gradient of less than 10%, anything between 11% and 20% is usually deemed moderately steep, whereas 20% to 35% are very steep.

How To Choose A Good Hill Builder

Hiring the right team is perhaps the most important aspect of a successful hillside build and protecting your investment. Before committing to a builder have a think about the following points to gain insights into their experience and professionalism.

    • Are they local? Do they have previous experience in the area you intend to build?

    • Ask to visit recent examples of their work

    • Request references from previous clients

    • Read online reviews, ask neighbours, friends and family

    • Engage in conversations with architects/engineers and other industry professionals

    • Check industry affiliations (Registered Master Builders Association and NZ Certified Builders)

Why Use Architectural Builders?

If you are looking for peace of mind when taking on a hill build, the number one piece of advice that will pay off in the long run is hiring local architectural build specialists experienced in bespoke hill design/build projects. It only makes sense to find people who have experience in similar types of projects and in the area you intend to build in.

Being able to trust in your build team will make all the difference. They will have the expertise to quickly and efficiently address any challenges that may arise while also understanding the intricacies of geo-spatial reports, structural integrity, foundational support, retaining walls, and water runoff needed for hill builds.

The right hill builder will mean you are better able to maximise the full potential of your build site while ensuring a harmonious integration between your home and its landscape.

How Much Does A Hill Build Cost

As a rough guide, building on sloped land is considered 20-40% more expensive. As a general rule, the steeper the slope the higher the increase in costs. Common factors that affect the cost of hill builds are:

    • Additional engineering requirements (structural considerations)

    • Architects/consultants (more complicated designs/plans needed)

    • Additional construction costs (bracing, reinforcing etc)

    • Groundwater considerations (retaining walls, drainage, waterproofing etc.)

    • Topographical challenges (Geo Tech reports, earthworks etc.)

    • Extended timeframes (most hill builds take 14 to 18 months to complete)

6 Top Tips For Building On A Sloped Site

Has this post ignited your passion for building on a hill? Then what are the secrets of good hillside design? And what should you keep in mind when thinking about building on a sloping site – take a look below for our top tips.

  1. Design For The Site. Don’t just take a house design that you like that was designed for a flat site and plop it on flat platform foundations. You are not choosing to build on a flat site, so think outside of the box! The key to successful hill homes that are distinctive and creative is to work with the contours of the land, carefully positioning your home to maximise the site’s utmost potential.
  2. Outdoor Living Location/Design. The key to ‘elevating’ (pun intended!) a great hillside build to an exceptional one is to give plenty of thought to how and when you most anticipate using your outdoor spaces. Think about where you’ll be spending time in the morning – do you prefer a sunny start to the day with your morning coffee? Or do you anticipate spending those long summer nights enjoying the late-night views? Is shelter from the prevailing winds and heat of the afternoon sun a priority?
  3. Keep The Flow. One aspect of hill builds that can be a bit tricky is the flow between the different living spaces, especially in split-level builds. While keeping the focus on maximising the views and natural light, it is essential to carefully consider front door access, bathroom locations, the interaction between indoor and outdoor areas, and airflow.
  4. Sun Sun Sun! While for some, the thought of sunlight streaming all day long can be a bit daunting on those hot summer days, keep in mind you can always install quality blinds and window coverings later to address overheating – it is hard (and expensive) to replace or resize windows and doors. Go for those stunning floor to ceiling windows if you want, or not – that’s what custom builds are all about!
  5. Always Use Experts. Investing in a good design team and professional architectural builders will definitely pay off in the long run. While only representing a small portion of the total project cost, your design team is making decisions that end up affecting every aspect of your build. By working with experienced local builders you’ll be better equipped to deal with challenges as they arise and get it right first time!
  6. Be Informed. One of the most common mistakes people make when building on a steep site is insufficient research and understanding before purchasing the land. If you are looking at building on a hill, consult with qualified and experienced hill builders to understand the specific possibilities and costs associated with the building.

We hope this article has helped shed some light on the advantages and intricacies of building on a hill site. If you are looking for specialist hill builders in Christchurch, feel free to call our team at LM Architectural Builders to discuss your requirements today.